radio amateur

Setting CW Cable For N1MM Problem

2010-02-20T10:23:00.002+08:00

Setting CW Cable For N1MM Problem

Source from: http://yb3td.com/

Newer technology require me to adapt and adopt. Before time, I’m a fanatic user of CT K1EA logging contest software. Then suddenly K1EA stop develop his software. It’s going worst when Windows XP go to market and complicated with no more serial ports (COM ports) and parallel port on newer version of notebooks or laptops. So no more possibility to keep using CT K1EA to help me logging during contest. Bye bye CT.

My head then turn to N1MM logging contest software. The only reason I choose (and only reason why I left CT) is N1MM can key up CW on my radio. N1MM can handle keying CW via serial port and trough serial port that converted from USB ports. As you know, newest notebooks are no longer equipped with serial/COM ports and parallel port. It’s replaced with USB ports, 3-4 ports for each notebook computers. So we have to buy a USB to serial cable adapter to convert our USB port to serial/COM port that compatible with N1MM requirements.

But unfortunately not all USB to serial cable adapter type can be used. Not only with N1MM, I found I can’t used also even with simple program like Hyperterminal. I don’t know why. Driver software was loaded. COM already set to COM8. But still can’t work. Here this the cable I was bought. The cable chipset is USB to serial adapter Semi-tech. This semi-tech usb to serial adapter as you can see on photo, has a white clear plastic cable cover. Inside the plastic cover is aluminium foil as interference shield. USB jack and serial jack DB9 are colored with blue-green clear PVC. This cable is not working to key CW on N1MM and simple loopback with Hyperterminal. I’m not test it with other gadgets.

Then I borrow USB to serial cable adapter from YD0NGA. It’s UMC211 Chipset Technology (Taiwan) but has Prolific chipset inside. The cable color is dark and different model with Semi-tech adapter. And whoala, this UMC 211 is work to key CW with N1MM. And another evidence of old aphorism, Good Thing is Not Cheap, Cheap Thing is Not Good. UMC211 price is US$1.5 while Semi-tech cable is only US$0.5 here in Surabaya city computer mall.

On N1MM side, some important things to notice:

1. set your COM port between number COM1-COM8. Because N1MM coded to work only on that COM range. N1MM programmer notice for COMs higher than COM8 are already a COM branches, not a root COM anymore. It will give some delay or even error during USB scanning.

2. Set DTR to “CW” while RTS to “always off”.

3. Make sure you USB to serial cable adapter driver is successfully installed.

To set you COM port, you can set it from Ports Device Manager. Klik Advance and you will see a radio button to change you COM setting.

So don’t wrong choosing cable. And happy contesting.

Installation Discussion

2010-02-20T01:40:00.001+08:00

(to Western Hemisphere,Eastern Hemisphere,Footprints by Dish Size)

Installation Discussion
Ground Pole/Pad Mount and Wind Loading
(to dish size list or tuning page)

GROUND POLE: The major item
here in setting the ground pole is plumb, plumb, plumb - make
sure the pole is perfectly vertical; though first thing, check
for obstacles in your viewing path
and choose appropriate pole for your dish diameter (see wind
loading). Rule of thumb on minimum hole diameter - four times
diameter of pipe. Rule of thumb on hole depth - minimum one/third
down (below ground) and two/thirds up (above ground). Rule
of thumb on gravel size for concrete - no bigger than one/half
distance of pipe to side of hole. Rule of thumb on concrete type
- never use 'quick crete', i.e. concrete with additives for one
hour curing, it will crack in years to come and sometimes as
little as in six months . If you are not using a premix of concrete
then use the one-two-three rule: one part cement, two parts sand,
three parts pea gravel. When cutting pole to length be sure ends
are square - it will cause you plenty of problems if they are
not. Remember that concrete shrinks when it cures (concrete does
not 'dry', it cures) and actually pulls away from surfaces as
it hardens so weld a flange, or spur, to the bottom of the pole
for to anchor pole into concrete as it hardens. A flange on one
side is sufficient, both sides is overkill. Sometimes I have
just drilled a hole thru the pipe and stuck a rod thru the holes
with no welding. When digging hole - get below frost line and
flare out the bottom of the hole so concrete will make a good
plug when poured (make the hole look like an elephant's foot).

Place a thick layer of gravel on the bottom of the hole, or
at least a brick but gravel 'seats' the pole better, and set
pole in hole on gravel. Do not try to pour the whole concrete batch at once. Make the first
batch stiff (thick), position pole in center of hole, and shovel
small amounts of concrete equally around the pole. If you shovel
too much concrete to one side at once, especially in the beginning
of the pour, it will push the pole to one side and you will lose
center; be patient and take your time here. Pour enough in first
batch to bring concrete about a foot up on the pole. Now take
a rod, something like a piece of rebar, but a shovel handle is
too thick, and gently 'rod' the concrete, i.e. push rod straight
down thru concrete to bottom of hole - be careful not to do so
in a manner that causes the pole to lose center. Do this no more
than ten to fifteen times, this ensures no air is trapped in
mix; if you rod more than that then the mix begins to come apart.
Check pole for plumbness all around, not just on one side, with
level or inclinometer - hold pole for a few minutes now (good
thing for assistant or mother-in-law to do). Do not be lured
into thinking that pole is plumb because top is level - that
depends on the saw cut; make the sides plumb. Make next concrete
batches with more water and gently shovel into hole in small
amounts being careful not to pour too much at a time or you will
disturb pole plumbness. The reason the second batch of concrete
is made with more water is because soupy concrete cures to have
more strength. Repeat rod procedure, extending only slightly
to level of first pour, and check for plumbness.

At this time set a PVC elbow in concrete that extends
out beyond the hole wall and is against the pole and extends
up the pole high enough to be above lawn mower or weed eater
height. You can cap top of PVC later with downpiece - what is
important now is to seal both ends of elbow with good tape to
keep debris and concrete out of pipe. I have set elbow in concrete
and set it above last pour - your choice - I usually set it in
pour at depth below grass root level. Finish pour to top and
rod last batch; sculpt the top so that concrete slopes away from
pole. If you want, bring concrete to above ground level or leave
below ground level so as to add a grass plug later. At this time,
pole should be difficult to move because of thick concrete in
first pour though later soupy pours will take some time to cure.
Recheck for plumbness and push pole to any direction required
to be plumb - it should not be far off, if at all, if you have
been checking regularly - hold.for a few minutes while you drink
a cup of coffee, tea, cola or have a smoke. In about an hour
fill the pole with very soupy concrete to at least above ground
level - this will add strength to the pole as well as prevent
future oxidation (coming from internal of the pole) of the pole
at the ground/air interface.

For four meter or larger residential antenna, use a larger
diameter pipe than recommended and place a reducer cap on top
when ready to install reflector, i.e. if the mount cap comes
ready for a 3.5" pipe then use a 4.0" or greater main
pipe diameter and weld a reducer cap on top with a 3.5"
diameter that the mount cap will slide on. For more info on pole
diameter, see wind loading. Remember:
When choosing the site for the ground pole be sure that when
the dish is rotated from arc to arc it will not touch anything
and that it will have a clear view of the satellite arc from
end to end.(top of page)

PAD POLE: Where hard rock
prohibits a ground pole, or for installations in a parking lot
or on a flat roof, it becomes necessary to anchor the satellite
dish with a little more creativity. The most easiest is to weld
a crosstie leg assembly with a welded support brace going from
each leg up to the pole; then weight down each leg to immobilize
the dish. I am currently in a rent house, flat roof, so do not
want to permanently install my dish in a concrete pad on the
roof so I use unopened eighty pound cement bags (not quickcrete
with gravel and sand but pure cement) on each base leg as a weight.
With rain, over time, it will harden like a rock and mold itself
to the base leg. For a rule of thumb, for an installation on
a flat roof atop an office building, for a 3m dish, use a total
leg base of eight to ten feet (four to five feet per side) and
use something like four inch channel for the leg and one or two
inch angle iron for the braces (do not use flat bar for braces
but you can use round bar). In practice, position the pole and
base on roof then level the base with shims so that the pole
is plumb then apply leg weights (use a pile of rocks if nothing
else). For my system, an eight foot dish on a one floor roof,
I have two foot length legs out of one inch angle iron with sixty
degree round bar braces from each leg to the side of the pole
- all welded. I have come out one-half the leg distance and up
at a sixty
degree angle to the pole. Note: Often after a weld, the legs
will 'pull' a bit. In my case, that occured however on the roof
I leveled each leg with shims so the pole was plumb then piled
the weights on the legs and and a few rocks around the pole.
Remember to check the pole for plumbness after piling on the
weights.

In lieu of the 'crude' system described above, you can use
a combination of a mount pole outfitted with legs set onto preformed
concrete end weights. Preform the leg weights, mass production
style, as concrete blocks, use ready mix sacks, i.e. not large
aggregate (gravel) and inset a 'J' bolt for both leg attachment
and pole leveling. Concrete is stronger the soupier it
is so do not wipe water off the top and if need be, on real hot
days, place a burlap sack on top and wet it down after your last
pour. On real cold days, add a combination of straw, newspapers
and rags on top to prevent freezeing. In designing your forms
use an assembly that you can bolt to a bottom plate (1"
plywood). Make the side boards at least from 2" x 6"s
to allow sufficient depth for the 'J' bolt. Depending on the
size of dish to anchor you can make the blocks with 2" x
8"s, 2"x 10"s or 2" x 12"s. On the bottom
of the form nail (or screw) a 'lip' all the way around (use a
1" x 6") and use this lip to bolt to the bottom plate.
The lip and bolt down prevents concrete from oozing out the bottom
of the form, use mimimum two bolt downs per side. When cured,
remove the bottom plate and hopefully you can dump out the mold
and reuse the form - concrete actually shrinks when it cures
so you are making a reuseable form.as the finished block will
pull slightly away from the form and will come out rather easily
but during the pour the form must be bolted down well to the
bottom plate. In lieu of 'J' bolts, you can take a threaded rod
and then thread nuts and washers to make the anchor in the block.
Make a jig for the top (from a 2" x 4") with a center
hole to place over the anchor bolt and thread a nut over the
exposed bolt to keep the bolt in place and vertical and to be
sure the bolt does not sink into concrete. Use the top jig, or
another board, to level the top before slipping in bolt, i.e.
wipe off excess concrete from pour. Use a mini-level (sometimes
called a torpedo level) to guarantee the bolt stays vertical.
Make the block in one pour and use medium stiff concrete at time
of pour but not too stiff that bolt will not slide in easily
- the bolt should slide in and concrete ooze around it easily
otherwise anchor will not be set to its best capability. Remember,
concrete actually shrinks as it cures so do not but in a straight
bolt without something to anchor it in the concrete or you will
compromise its stabilizing effect on the dish mount. Do not use
anything less than a 3/4" diameter bolt. If you are using
allthread for the bolts and/or have in mind to saw off the bolt
tops after concrete has cured, i.e. to level all the emplaced
bolts, thread a nut onto the bolt before sawing so that after
the cut you can work the nut off and reconstitute any threads
damaged by sawing.

The last real option to anchor a dish without a ground pole
is to pour a complete concrete pad.
The major
aggragation to this is inseting the bolts to correctly align
with the dish pole support structure. The other option to inseting
bolts is, after concrete pad has completely cured, use
an epoxy system to anchor the required bolts. This technique
requires drilling the proper hole into the concrete then using
the epoxy system to secure bolt; a manufacturer's variation on
this is to epoxy (into the hole) the unit the bolt will thread
into then, of course, install bolt. These are proven, structurally
rated epoxy techniques and make a very nice installation; check
with any high quality hardware store to located the product (read
all instructions when using the epoxy system as there is little
for error once you begin the epoxy process). To properly mark
hole locations, place the mount on the finished pad then mark
with a chisel where to drill or, better, drill a starter hole
with a masonry drill bit before moving the mount to drill the
correct size hole.

The other option, for a full ground pad, instead of inserting
bolts, is to pour the pad (to level the install site) then use
a brace-leg-weight system to anchor the pole.
For the pad, set the pole with legs at the proposed location
and mark the size pad desired; then, remove pole out of the way
(of course), build your form. For a weight anchor system, minimum
pad thickness is using a 2" x 4" for the form edges
for a 2.0m or less diameter dish and go to a 2" x 6"

for a 3.0m dish and a 2" x 12" for anything greater.
Be sure to frequently stake the form perimeter as concrete is
heavy and will push out on the form. Nail form edges into each
other. Be sure top of form is level in both directions. If pad
site is unlevel and the bottom of the form is not touching the
ground in any place then fill inside of form with dirt to prevent
concrete leakage and pack the dirt firmly. Try to mix all concrete
you will need in the beginning then shovel into form. Resist
the temptation to throw in rocks/bricks, etc., to fill your pad
quicker. When form is halfway filled, lay in a layer of concrete
wire mesh then finish pour and level off top with a board, i.e.
scrap off excess concrete. Do not scrap off excess water on top
of pour; if anything, after an hour, spray more water on top
of curing pad. The extra water on top will assist in preventing
cracking. In laying the mesh on this small of a job, it is best
to do so in middle of pour rather than lay on ground and fill
concrete on top and try to 'shake' it up. The mesh is not so
much to add strength to the concrete but to hold it together
over time (maintain its structural integrity) should the pad
crack (due to whatever reason). In case of excess freeze-thaw
phenomena locations, i.e. in 'cold' country, using a weight-leg
pole assembly, rather than insetting attachment/leveling bolts
in the concrete, allows for easier leveling adjustment should
the pole become non plumb. When running cable, bury it, if possible,
to the pad then run through conduit atop pad to the pole; attach
conduit with strapping clamps to concrete using plastic screw
anchors inserted into drilled holes (use masonary bit) in the
concrete.(top of page)

WIND LOADING:The bottom line
on wind loading (on the surface of a dish) is the bigger diameter
the dish the more wind it traps and the more the dish faces into
the dish the more wind it traps. Mesh dishes act as solid dishes
at about fifty miles per hour though will still experience approximately
40% less force than a solid dish. To calculate the pressure on
the base of a pole, or where ever the pole is attached to a constraining
rigid structure (for instance, side wall of a house), multiply
the pole length by the factor in the chart, for the desired windspeed,
to get pounds per square foot (psf); then divide by 144 to get pounds per square
inch (psi). This is a crude guide for you as other factors come
in play in determining actual shear forces on a mount pole from
wind - dish weight does factors in, i.e. the heavier the dish
the more force it will bear if the dish begins oscillating (which
contributes to fatique), and it changes the pole strength factors
if you have poured concrete into the pole. From the pressure
on the pole base and the manufacturer's characteristics of the
mount pole you can see if your chosen pole diameter is large
enough and its thickness sufficient to resist failure under maximum
winds. Believe me, nothing is more aggravating than dealing with
a bent mount pole after a windstorm. Use dish manufacturer's
guidelines in choosing a mount pole - do not leave it to chance,
especially on heavy large dishes. Remember, a good ground
pole installation, or pad mount,
and depth of pole, prevents a dish from eventually rocking or
leaning in the ground but does nothing to resist shear bending
above the ground. For dish diameter below 2.5m, with minimal
pole height, you can use schedule 80 (USA ASTM code) 3.5"

diameter pole. For dish diameter 3.0m using and regular height
poles (mesh, fiberglass or solid dish) and taller poles for diameter
2.5m, use schedule 40 3.5" diameter pole. For taller poles
above ten feet, in the previous two examples, use some type of
side wall support or turnbuckle/wire rope bracing system or expect
wind action on the Ku satellites. For 4.0m dishes and commerical
installations (not az/el type mount), use schedule 80 pole and
go to 4.0 and greater pole diameter - ask dish manufacturer.
For these larger diameter dishes they often refer to the 'pole'
as a pedestal and usually the manufacturer will recommend and
provide the pedestal or a tower for dish support.

Under no conditions, use PVC (plastic pipe) for any dish mount
(I have never heard of it being successful), and never underestimate
the power of inclement weather to damage your dish. For commercial
installations, I have installed retainer clips around dish lip
attached to wire rope (3/8" wire rope minimum) attached
to 'J' bolts in concrete posts so if the mount failed (not the
pole) then the dish would not fly around. Although we think of
failure of the pole, the shear strength of the bolts in the mount
are to be equally considered in your design criteria in wind
loading. In summary, if you have continued worries about pole
failure, have an engineer calculate wind loading forces on reflector
and the force moment at the ground/air interface (bottom of pole)
and choose pole diameter accordingly. I also use three support
cables (3/8" wire rope minimum) placed two/thirds of the
way up the pole for stabilization when needed to stay on track
in wind or for a free standing tall pole, and tighten with a
turnbuckle. Weld 'eyes/ears' on pole for wire rope and anchor
at a thirty degree angle from pole to 'J' bolts seated in concrete
pods. Your local hardware store will have everything you need.

(top of page)

Challenge yourself

2010-02-20T01:10:00.001+08:00

DIY Horn
Type Antenna

Challenge yourself on others satellite and
share your tested result to others SATCRAZY club member.

Try C Band channel.

You can use the Paper Card board with sticking
the aluminium foil on top, then make it as the horn shape to test.

From: James

Receiving	KU Band - Vertical - Astro TV
Signal	70%
Patern	Square
Dimension	35cm x 35cm
Length	71cm

Very
easy to collect the signal.

China Horn Antenna

Horn Antenna from China
Satellite crazy.

Satellite	PAS8 (166)
Venus	Sheng zhen China
Year	2000

Signal
strength

2 KU LNB in one Astro dish

2010-02-20T01:00:00.002+08:00

2 KU LNB in one
Astro dish

Top	ST1ku
Bottom	NSS6

Due to Measat (91.5 degree) and ST1 (88 degree)
is too close. It a bit hard to get both. You spend some time to try it.

Tested by James

Date : 25/02/2008

Ku dish size comparison.

ST1
- C Band

Astro
Dish with C-Band LNB

Suitable for satellite:

ST1 (TBL TV - annual card)

ST1 - KU Band

Astro
Dish with Original KU LNB

LNB type = Universal *

LNB Freq. = 9750Mhz*

Adjust the Dish down 1 mm and little bit
right as Astro original angle and direction.

Origin = Taiwan

Free Channels : 6

Pay Channels : 5
(1 duplicate channel as Free)

Asiasat
3

4 FT
Dish with C-Band LNB (Free TV)

Suitable for satellite:

Asiasat 2

Asiasat 3

JCsat 3

Agila 2

Palapa

6 FT
Dish with C-Band LNB (Free TV)

Suitable for satellite:

Asiasat 2

Asiasat 3

JCsat 3

Agila 2

Palapa

Pas8

And much more

6FT with Motorized Control

Electronic circuit schematics

2010-02-20T00:18:00.002+08:00

LINKS

Source from: http://www.district87.org/staff/waltonm/CircuitAnalysis/Electronic%20circuit%20schematics.htm

Alarms and security
related schematics

Lessons In Electric Circuits

2010-02-20T00:09:00.003+08:00

Lessons In Electric Circuits -- Volume V

Chapter 9 CIRCUIT SCHEMATIC SYMBOLS

Wires and connections
Power sources
Resistors
Capacitors
Inductors
Mutual inductors
Switches, hand actuated
Switches, process actuated
Switches, electrically actuated (relays)
Connectors
Diodes
Transistors, bipolar
Transistors, junction field-effect (JFET)
Transistors, insulated-gate field-effect (IGFET or MOSFET)
Transistors, hybrid
Thyristors
Integrated circuits
Electron tubes

Wires and connections

Older electrical schematics showed connecting wires crossing, while non-connecting wires "jumped" over each other with little half-circle marks. Newer electrical schematics show connecting wires joining with a dot, while non-connecting wires cross with no dot. However, some people still use the older convention of connecting wires crossing with no dot, which may create confusion.

For this reason, I opt to use a hybrid convention, with connecting wires unambiguously connected by a dot, and non-connecting wires unambiguously "jumping" over one another with a half-circle mark. While this may be frowned upon by some, it leaves no room for interpretational error: in each case, the intent is clear and unmistakable:

Power sources

Resistors

Capacitors

Inductors

Mutual inductors

Switches, hand actuated

Switches, process actuated

It is very important to keep in mind that the "normal" contact status of a process-actuated switch refers to its status when the process is absent and/or inactive, not "normal" in the sense of process conditions as expected during routine operation. For instance, a normally-closed low-flow detection switch installed on a coolant pipe will be maintained in the actuated state (open) when there is regular coolant flow through the pipe. If the coolant flow stops, the flow switch will go to its "normal" (unactuated) status of closed.

A limit switch is one actuated by contact with a moving machine part. An electronic limit switch senses mechanical motion, but does so using light, magnetic fields, or other non-contact means.

Switches, electrically actuated (relays)

Connectors

Diodes

Transistors, bipolar

Transistors, junction field-effect (JFET)

Transistors, insulated-gate field-effect (IGFET or MOSFET)

Transistors, hybrid

Thyristors

Integrated circuits

Electron tubes

Plug n Play Cables

2010-02-19T23:58:00.002+08:00

Plug n Play Cables are made for the Alinco
DR-135T 144 MHz , Alinco DR-235T 220 Mhz and the Alinco DR-435T 440 Mhz radios
to be interfaced with the IRLP Version 3.00 Board.
Source from : http://www.irlpcables.com/

The male DB9 connector connects to the back of

the Alinco
radio.The female DB9 connects to the

IRLP interface board.

The two 1/8
inch stereo connectors are clearly

marked and plug into your IRLP node soundcard.

The
Alinco DR-x35 series radios have a female DB9

connector on the back. When you use a Plug n Play

cable, all the interface connections from the IRLP

board to the radio are made through this connector.

These radios work great for IRLP nodes.

NOTE:
Please check the jumper settings on the

IRLP interface board to make sure that

COS DETECT is set to LOW.

Cables for other radios and or kits are available on special
request,

For Ordering information please contact Marshall, ke6pcv via email at:

ke6pcv@cal-net.org

PLUG n PLAY CABLES

Copyright 2007 IRLP Cables Web
Design & Host

Last Updated
September 17, 2008

13.8V 20A linear power supply

2010-02-19T23:46:00.004+08:00

13.8V 20A linear power supply

Source from: http://ludens.cl/Electron/Ps20/Ps20.html

Linear power supplies for communication equipment are among the most commonly
built electronic projects. Almost every technically inclined radio amateur
has built at least one. But unfortunately most designs, even those published
in well respected books, are unnecessarily complicated, or have some specific
drawbacks. The design presented here is a little bit unusual in its arrangement,
but offers some advantages over the usual designs that I will explain in
the following paragraphs.

Basics of linear power supplies

First, let's start from the basics: A linear power supply has a transformer
that steps down the line voltage to some voltage that is higher than what
will be required at the regulated output. Then a rectifier and a filter
capacitor transform the low voltage AC into a moderately filtered DC that
still is unregulated and has some ripple. Finally, a regulating circuit
"burns off" the excess voltage, leaving only the exact amount desired at
the output, typically 13.8V for communication equipment.

One typical mistake made by many amateur designers is using a transformer
that has a voltage that's too low for the combination of rectifier, filter
and regulator used. The situation is this: You need 13.8V at the output
at all times. Your regulator eats up a certain minimum voltage, which depends
on its design. Many regulators need at least 2V across them, so you need
15.8V minimum at the worst time across the filter capacitor. This is the
voltage at the minimum point of the ripple waveform, but the capacitor
needs to be charged to the maximum of this ripple voltage. So, the size
of the capacitor defines how much additional voltage you need for this.
A 60000uF capacitor, used at 20A, and discharging during almost a half
cycle at 50Hz (10ms), will drop the voltage by almost 3.3V. So, you need
to charge the capacitor to at least 19.2V under the worst conditions! If
you are using a bridge rectifier made from silicon diodes, which loose
about 1.2V each at peak current, then you end up having two diodes conducting
at the time of charging the capacitor, dropping a total of 2.4V. So, the
transformer needs to develop 21.6V peak voltage. This happens under heavy
load, as most of the charging of the capacitor happens during a very short
time, so there is a lot of voltage drop in the transformer, maybe 10 to
15%, depending on its size. So, you need to consider a transformer that
develops about 24 or 25V peak voltage. Finally, you need to consider that
the power line from which your design gets its power is not 100% stable!
Allowing for 10% worst case sag in the power line, you end up needing a
transformer that at nominal line voltage and small load provides about
27V peak! That would be 19V RMS.

If you use a transformer with a lower rating, or a smaller filter capacitor,
or a regulator that has a minimum drop of more than 2V, then your power
supply will loose regulation under some conditions. Many amateur designers
run into this problem.

On the other hand, if you use a regulator with a lower drop, and/or
a larger filter capacitor, then you can slightly ease the transformer voltage
requirements. This can be very useful to keep the filter capacitor voltage
rating requirement at 25V, since otherwise you would be forced to use a
35V capacitor, which is much larger and more expensive. A lower transformer
voltage is also an advantage from the efficiency point of view. After all,
the complete excess voltage has to be burned off by the regulator, causing
a huge power loss and requiring a large heat sink!

Another issue is what kind of pass elements to use for the regulator.
MOSFETs are not a good choice, because they are much more expensive than
bipolar transistors for a given minimum voltage drop and power dissipation.
So, almost every power supply uses bipolar transistors. NPN transistors
are usually preferred over PNP ones, because they are cheaper for a given
performance, and there is wider selection. So far, so good. But most designers
place their pass transistors on the positive side, in emitter-follower
fashion, adding a Darlington driver (or two Darlington stages). This is
a very bad choice for several reasons: One, each transistor connected in
that way produces a minimum voltage drop of 0.6 to 0.7V. A three-stage
arrangement, as is often needed, would have a minimum drop of around 2V,
plus the drop caused by any equalizing resistors! Also, the transistor
collectors, which are connected to the cases, are at the unregulated positive
voltage, and thus require insulation from the heatsink and power supply
case. The necessary mica insulators add a huge amount of thermal resistance,
making it much harder to cool the transistors properly.

This design

In the power supply presented here, several measures were taken to get
rid of the problems mentioned above. The pass transistors are located in
the negative rail and connected in common-emitter configuration rather
than as emitter-followers. Thanks to this, the regulator's minimum voltage
drop is extremely low, only about 0.1V for the transistors plus 0.5V for
the equalizing resistors. The other advantage is that the collectors are
directly connected to the negative pole of the power supply's output, which
in most applications is grounded. That means that no insulation is required
between the transistors and the grounded power supply cabinet! This eases
the cooling very considerably. Thanks to the low regulator drop, a low
cost 25V filter capacitor can be used.

The voltage adjustment potentiometer is arranged in such a way that
if the wiper contact fails, the voltage will go down, never up. This is
an important safety issue, avoiding damage to connected equipment.

Here is the schematic diagram: Use the full resolution
version for printing.

This power supply delivers a highly regulated 13.8V, adjustable over
a moderate range, at a continuous current of up to 20A. It is current-limited
to approximately 25A, and short circuit protected for as long as the heat
sink can keep the transistors cool enough. It is probably the simplest
design that can accomplish this.

Some notes about this circuit:

- Use a transformer for the primary voltage you need. The 3A fuse is
for 220 or 240V primaries. If you use something in the neighborhood of
110V, use a 6A fuse.

- The rather high transformer rating of 35A accounts for the losses
that occur due to the capacitive input filter. If your transformer is rated
for capacitive input, then a 25A value is enough.

- Of course you can make up C1 by placing several smaller capacitors
in parallel. Likewise, the 0.1 Ohm, 5 Watt resistors can be made up by
several in parallel, for example by 5 resistors of 0.5 Ohm, 1 Watt each.

- The LM336Z-5.0 voltage reference IC should not be replaced by a zener
diode. Zeners are not nearly as stable. A different voltage reference IC
can of course be used, if R2 and R3 are modified for the different voltage.

- D1 and Q2 through Q6 need heatsinking. Only Q2 needs insulation. D1
dissipates up to 60W, Q2 up to 25W, while the pass transistors dissipate
up to 30W each in normal use, but may reach a level of 130W during short
circuit! Take this into account when choosing the heat sink!

- R5 exists only to make sure that the transistors can actually be driven
off. The 741 is not a single-supply operational amplifier, so it cannot
drive its output very low. If a true single-supply opamp is used, then
R5 becomes unnecessary.

How it works

U1 provides a regulated reference voltage that's always 5V below the positive
rail. U2 compares this reference voltage to a sample from the output (ground
against positive rail) and drives a Darlington transistor connected as
emitter follower, which in turn drives the four pass transistors connected
in common emitter configuration. Four resistors equalize the current through
the transistors, and one of these resistors does double duty by serving
as current sense resistor. If the current through this resistor exceeds
about 6A, then Q1 will start conducting, swamping the drive from U2 to
the negative rail and thus limiting the output current.

No parts were added to control frequency response, loop damping, etc.
All trust was placed on the 741's rather low frequency response and high
stability, combined with a 1000µF capacitor across the output. In
practice this has proven to work well enough, but purists may want to experiment
with the loop response and add some compensation capacitor.

Construction notes

A power supply like this is simple to build, but it uses large and heavy
parts, so physical construction should be strong. The 630VA transformer
is heavy, and even the heat sink will not be small. So, build or buy a
good, solid, sturdy cabinet. Try to use aluminum for the cabinet, since
steel will vibrate from the transformer's stray field. The cabinet should
be very well ventilated.

The heat sink needs to be large. How large...? Well, it
depends. Do you want your power supply to be short circuit protected without
a time limit? That will require a really large heat sink!

In normal use at the 20A level there will be about 200W dissipation.
The diode bridge can run at 35A when kept cool at 25 degrees Celsius (which
is utopic, by the way!). As silicon can withstand 150

degrees before melting down, the 35A bridge running at 20A can survive
about 75 degrees case temperature. The pass transistors are rated for 115W
at 25 degrees, which means that at 30W each they can run safely at almost
120 degrees. The driver transistor can dissipate 60W at 25 degrees, so
at 25W it may heat up to 98 degrees.

The thermal resistance from the bridge to the heat sink is probably
better than 0.2 degrees per Watt, so the bridge is happy if the heat sink
stays below 65 degrees. The power transistors probably have around 0.5
degrees per Watt of thermal resistance to the heat sink, so they need the
heat sink to stay below 105 degrees or so. Easy. The limiting factor in
this case is the driver transistor, because it needs to be insulated! That
transistor with its mica insulator will have about 1.5 degrees per Watt
thermal resistance, thus requiring the heat sink to stay below 60 degrees
or so. You may want to replace the TIP122 by a Darlington transistor having
a higher power rating, so the bridge would become the limiting factor.

In the above case, you need a heat sink that doesn't warm up to more
than 60 degrees Celsius while dissipating 200W. If you consider a highest
ambient temperature of 30 degrees, then the heat sink may heat up only
another 30 degrees above ambient. That is a thermal resistance of 0.15
degrees per Watt, which means a HUGE heat sink! If you really want to run
this power supply at 20A continuous duty, you may be better off with a
more moderate (still large) heat sink plus a small fan that blows air through
it!

You may use a rather small heat sink, rated for 0.7 degrees per Watt
or so, if you will use this power supply for a typical HF transceiver that
needs 20 to 23A peak, but at an average of no more than 5A or so. This
is what many commercial power supplies do.

If you use a small heat sink, and run the power supply at high average
current, you WILL burn it up. Take my word for it. Too many people have
blown up their power supplies in this way.

Just for fun, lets see how much the heat sink requirement increases
if you want protection against continuous short circuit. The total power
dissipation would be around 550W. The bridge and driver transistor would
run much like they would at 25A load, while the dissipation in the pass
transistors is hugely higher than normal, reaching about 130W! As the 2N3055
is rated for 115W at 25 degrees, it means that the transistor cases would
have to be kept below 9 degrees! Considering the 0.5 degrees per Watt of
thermal resistance between each transistor and the heat sink, the heat
sink would need to stay below -56 degrees Celsius! A giant heat sink running
at the south pole maybe could just do the job, otherwise you would need
a cryogenic system! Needless to say, it is impractical to implement indefinite
short circuit protection in this way! It would become practical if you
increased the number of pass transistors, increasing proportionally the
equalizing resistors' values, but even then it would require a large heat
sink. A foldback current limit would overcome this problem, but it brings
along other problems of its own, like the power supply shutting down when
charging a capacitor in some equipment. I believe that the best compromise
is to build this circuit as shown, using a reasonably oversized heatsink,
and shut it off quickly when a short circuit happens, before the transistors
can overheat. After all, a 25A short produces a spark that's obvious enough
to notice!

A note on R11

I originally did not have R11 in the design. A fair number of readers built
the power supply and had good results. But then I got a mail from Carl
Ressel, who built it and tried it out feeding a variable voltage onto C1.
Very reasonable, only that without R11, Q2 took a very high current while
the input voltage was too low to allow the supply to produce normal output!
This situation could be fatal for Q2 in the event of a brownout. With the
added R11, the problem is solved. This shows how easy it is to overlook
a situation that normally does not happen, but sometimes can! A good design
must be able to handle any situation. Thanks, Carl, for this test!

I did not make a printed circuit board. Anyway, the transformer, fuse,
switch, connectors and filter capacitor are mounted to the case, while
the 5 power transistors, the 4 large equalizing resistors and the rectifier
bridge are mounted on the heat sink. This leaves so few components available
to mount on a board, that it doesn't pay to make a PCB. I suggest you mount
the remaining components on a piece of perfboard.

The quality of the voltage regulation depends mainly on how you build
this project. The single most important factors for good regulation are
that the ground connection of R3 must go DIRECTLY to the negative output
connector, while the top of R2 and of U1 must go directly to the positive
output. Everything else is less important.

I suggest that the case is connected to the negative output ONLY via
the pass transistors' cases, in order to avoid any ground loops.

This is a nice beginner's project, as all components are easily available
all over the world, the cost isn't extreme, the circuit is very simple,
and the resulting power supply will be useful for an entire ham radio career.
For more advanced builders, I suggest to try the 40A
switching power supply, which is much more elegant, efficient, powerful,
smaller and lighter, costs about the same to build, but is much more complex.

Ten Dollar Miracle Whip Clone

2010-02-19T23:34:00.005+08:00

Ten Dollar Miracle Whip Clone
Source from: http://kl7r.ham-radio.ch/

Ten Dollar Miracle Whip Clone

I bought a 6 foot whip and 25 ohm rheostat at radio shack and wired them up like this:

             ----

             \  /    6 foot whip

              \/    

              |

              |  

              \

              /

 rf in  ----->\      25 ohm radio shack rheostat

              /

              \

              |

             ---

             ///     gnd

I did some experiments with it ( off a quarter mile with my xyl reading base rig

s=meter back over 2 meters). 

Here are HFPACK thread discussions about it:

----------------------

Date:  Tue Dec 30, 2003  1:27 am

Subject:  1500 miles on $5 homebrew Miracle Whip

I talked to KQ6XA yesterday standing in my back yard running

an FT817 on battery power at 5 watts. I live in Juneau

Alaska. That is 1525 miles (2454.46 km)

This was on the HFPACK freq of 18.157.5 USB.

My home brew miracle whip:

6 foot RadioShack extendable whip

(I forget what this cost- you could use a tv antenna whip)

25 ohm RadioShack wirewound potentiometer (rheostat) (about $3)

A piece of circuit board to mount the pieces (junkbox)

An SO239 (female PL259) (junkbox)

A male to male pl259 (junkbox)

Circuit:

Not much to it.

Drill a hole for the center of the 239 in the circuit board

Solder the shield of the SO239 to the circuit board

Drill a hole and mount the rheostat

Center pin from SO239 goes to center connector (wiper)of rheostat.

Shield of SO239 goes to bottom connector of rheostat

Antenna goes to top connector of rheostat

make sure the antenna is insuated from the circuit board and

bind it to the circuit with some tiewraps

I can put up a picture if anyone is interested.

Comments:

The rheostat acts like an autotransformer at RF frequencies.

I am always able to get a 1:1 match on it.

It tunes so easily that I think it is part dummy load and part

autotransformer.

(Ever try using a 100 watt lighbulb as an autotuner? Ive done

it. Its a bit frightening but it works.)

I used a big electrician's wirenut as a knob for the rheostat

I can put up a picture if anyone is interested.

[Mike KL7R]

--------------------------

Mike,

Please send or post the pics for the antenna.

You could email them to me directly.

73

Fritz

WD9FMB

---------------------------

Mike, I would love to see a picture of the homebrew

miracle whip. Rusty de KC0LMS

---------------------------

Sounds like a real leaky dummy load to me.

Al, N8ARO

---------------------------

> Sounds like a real leaky dummy load to me.

I remember my elmer telling me that when he was waiting for his

novice license, he practiced sending CQ into a light bulb and

someone in the states came back to him on his light bulb!

---------------------------

>

> > Sounds like a real leaky dummy load to me.

>

> I remember my elmer telling me that when he was waiting for his

> novice license, he practiced sending CQ into a light bulb and

> someone in the states came back to him on his light bulb!

I've heard this hundreds of times but how do you actually do it?

Just pump the transmitter output into a light socket? No matching

network or resistance required? Is the bulb rating equal to the out

put of the rig, i.e. 100w rig = 100w bulb?

MarkF

K1MKF

---------------------------

> K1MKF wrote:

>> kl7r wrote:

>> ...sending CQ into a light bulb ...

> I've heard this hundreds of times but how do you actually do it? ...

No, don't do it. That was in the tube days.

Nowadays it would blow the finals. You could use a 50 ohm dummy load

though and accomplish the same trick, as coax wil radiate. My guess is

that you won't get out much on ladder line into a purely resistive load

though. There is a nice article on RF, coax, baluns, etc. In the recent

QEX.

We used a light bulb for a while but switched to a parallel fan-like

cluster of 10 500 ohm 10 watt resistors (not wire would as they would be

inductive) to give 50 ohms at 100 watts, and them immersed that in a

gallon paint can filled with transformer oil acquired from a neighbor at

the power company so it could take more power. I remember seeing it

bubbling out during a VHF tune-up with an old tube-type Motorola X53GGT

2m transmiter. I shudder now to think what was in the transformer oil,

but it was the early 1970's so I don't know for sure.

Leigh

WA5ZNU

-------------------

>

> I've heard this hundreds of times but how do you actually do it?

> Just pump the transmitter output into a light socket? No matching

> network or resistance required? Is the bulb rating equal to the

Yes thats what I did one day. Ran coax to a litebulb socket.

It is a bit frightening on a solid state rig. The swr spikes

up (ie a dead short) when you first start transmitting

but when the filament starts glowing white after a second or so

the swr drops down to 1:1.

I paralled my loop antenna across the light bulb and

was able to use it on multiple bands with the same effect.

I quit after a night of experimenting and proving to the

guys on my favorite net that it worked.

I dont think I would recommend this if you have a solid

state rig. A tube type final can handle the swr spike a bit

better than a solid state rig.

KL7R

------------------

> I've heard this hundreds of times but how do you actually do it?

> Just pump the transmitter output into a light socket? No matching

> network or resistance required? Is the bulb rating equal to the out

> put of the rig, i.e. 100w rig = 100w bulb?

> ....

I can't imagine sending in much power with solid-state finals, even

with a tuner, as its a very small inductor in series with a resistor

that changes dramatically in value with applied power and time. I've

only ever heard of it done with tube rigs to the point of lighting the

bulb. At low enough power, though, one could combine a few bulbs in

series and parallel to get to 50 ohms with some inductive reactance,

and be fairly stable as long as you never put out enough current to

raise the temperature of the filaments significantly.

73,

tim

-----------------------

> I can't imagine sending in much power with solid-state finals, even

> with a tuner, as its a very small inductor in series with a resistor

> that changes dramatically in value with applied power and time.

Thanks for all the replies. I think I'll just stick with my trusty

MFJ dummy load and some cheap coax.

MarkF

K1MKF

--------------------

Hey Mike we have been kidding you about the Dummy Load Antenna, however, it

does sound simple and interesting.

Could you run some field strength testing sometime at different SWR

settings. A 1:1 SWR may be all resistive from the rheostat and you may

radiate more RF at a greater SWR. Just a thought.

Al. N8ARO

--------------------------

Al I am planning to do some A/B testing of the rheostat MW

and a same sized whip with a BLT tuner. The idea of using a

field strength meter is a good one. Maybe my wife who is

also a ham could be my "field strength meter". That way I

could go out of the near field of the antenna and see how

they act a bit further out.

A note here to all:

I must give credit to Bonnie KQ6XA.

She made a version of this antenna before I did that did pretty

well in the antenna shootouts.

The original article in QST mentioned using a rheostat body

as the wiper which contacted the autotranformer toroid.

I thought since the rheostat is inductive at rf that you could

just use the rheostat itself and so went to radio shack to

look for wirewound pot.

Before I got my version of the MW built, I found Bonnie's version

in the HFPACK shootouts which also uses a rheostat -just a much

larger one. Interestingly her version (called a Wonder Whip)

did pretty well in the 2002 hfpack antenna shootout - only down

half an S unit from a full sized vertical.

Check out:

http://www.qsl.net/hfpack/antennas/shootoutvertical2002.html

-------------------

I went out tonight (PS it is 5 above here gorgeous and clear).

I took out the radioshack rheostat MW and a NORCAL BLT with a

duplicate whip attached to one leg of the norcal blt and the other

leg of the norcal blt shorted to ground.

I walked about a quarter of a mile away from our house and setup

both antennas (the 6'MW with a 25 ohm rheostat and BLT/6'whip)

I had my wife via 2 meters read me back S-meter readings on my

base rig.

The Rheostat mw did much worse than the BLT whip.

S6 vs S1 !

So I guess it is mostly dummyload :(

I did try a near field test of SWR vs field strength.

The fieldstrength seemed greatest when the SWR was "2 bars" [on my f817].

After dropping the swr to zero, if you kept turning the pot

fieldstrength would drop. In the far field there was no noticable

difference in the SWR setting vs field strength.

So it appears that if you get a broad null, the best position

of the pot should be at where it just hits "no bars" and

no farther.

A lower ohmage rheostat would have less resistive loss

but I dont know where to find a low value rheostat locally.

Hey, The good news is that it means I was 30 db down from a 6 foot

whip and a BLT and still was able to talk 1500 miles.

So the plan now is to remove the nichrome wire and replace

with #30 magnet wire and see what happens. My radio shack

store has 3 or 4 more of the 25 ohm rheostats in case there

no improvement or if I crater the current one.

Mike

KL7R

---------------------------

I pulled apart the rheostat and pulled off the nichrome wire

and wrapped the core with #30 magnet wire then sanded the inside

of the wire to expose the bare wire.

The receiver peaks are much sharper now

The transmitter SWR dips are much sharper also.

It seems to need a counterpoise more now.

The resistance of the magnet is about 1.5 ohms so this

version must be nearly completely inductive.

Ill do A/B tests tmw..

--------------------------------------------------

Mike, thanks for sharing all you fun and hard work with us.

Al, N8ARO

----------------------------

I did the A/B tests this morning

After replacing the nichrome wire with #30 magnet wire

the tests showed an improvement but still not as good

as a BLT tuner and whip.

The field strength readings this time were:

BLT/Whip S9

Rheostat body with #30 wire and whip S7

So the homebrew mw is down 12 db instead of the previous 30 db

Or saying it another way:

Replacing the nichrome wire with magnet wire was worth 18db or

3 S-units.

I think Ill quit at this point.

I might try putting an L network at the base of the whip

sometime and see if it comes close to the BLT/whip combination

Thanks for the feedback,

Mike KL7R

---------------------------

I will say that I have used it for QS0s to other parts of Alaska (600+ miles)

and have talked to a fellow walk-about in seattle who was running an ft817 and

a MW.  And , as I mentioned at the beginning of this,  I did QSO with California

from here in Alaska standing in my back yard with the rig and antenna in one

hand and the mic in another.

I keep the miracle whip in my "qrp bag"   I use it (and a 1 foot square

shielded loop) for signal DF-ing.   It is cool to take along to the ham club and

use for testing and bragging rights but I dont use it every day.  I am a fan

of big wire antennas (big wire loop antennas actually).   I actually use an

end fed piece of wire (88 feet) and a BLT tuner for most of my in the field qrp

work.

73 Mike

Radiation Plots

2010-02-19T22:22:00.001+08:00

Radiation Plots

Our first plot shows the elevation pattern in both the broadside (white trace) and end fire (yellow trace) directions for a height of 4 wavelengths, or 560 feet. Note the substantial high angle radiation in all directions, in addition to the excellent low angle lobes.

This plot shows the elevation patterns at a height of 2 wavelengths, or 280 feet.

White trace is broadside. Yellow trace is axial (off the ends).

Still Lots of high angle radiation.

This plot shows the elevation patterns at a height of 1 wavelength, or 140 feet.

White trace is broadside. Yellow trace is axial (off the ends).

The secondary lobe is down to 47 degrees, but the primary lobe is up to 14 degrees.

This plot shows the elevation patterns at a height of 0.7 wavelength, or 98 feet.

White trace is broadside. Yellow trace is axial (off the ends).

The primary lobe is up to 20 degrees.

Note the large vertical lobe which has appeared!

This plot shows the elevation patterns at a height of 1/2 wavelength, or 70 feet.

White trace is broadside. Yellow trace is axial (off the ends).

Now that's a classical dipole pattern!

This plot shows the elevation patterns at a height of 0.3 wavelength, or 42 feet.

White trace is broadside. Yellow trace is axial (off the ends).

We are entering the "skywarmer" mode here.

This plot shows the elevation patterns at a height of 0.1 wavelength, or 14 feet.

White trace is broadside. Yellow trace is axial (off the ends).

This plot shows comparative elevation patterns, in the broadside direction only,

White trace is for 2 wavelengths, 280 feet.

Yellow trace is for 1 wavelengths, 140 feet.

This plot shows comparative elevation patterns, in the broadside direction only.

White trace is for 0.7 wavelengths, 98 feet.

Yellow trace is for 0.5 wavelengths, 70 feet.

This plot shows comparative elevation patterns, in the broadside direction only.

White trace is for 0.5 wavelengths, 70 feet.

Yellow trace is for 0.3 wavelengths, 42 feet.

Pink trace is for 0.1 wavelengths, 14 feet.

This page is published by Mike Banz, AA3RL
as a service to the Amateur Radio community.

Please distribute freely.

The author welcomes any questions, criticisms, or compliments via email.

email Mike with comments or questions.