MACKAY EXPEDITION RADIO



PLAN

Document radio:
photographs,
drawings.
Research the radio use.
Restore cabinet:
remove hardware,
glue the timber that is falling apart,
sand rough wood
preserve pencil notes and frequencies on back of panel (clear lacquer)
prime (pink primer)
final coat (grey oil based paint)
reattach hardware (hinges, screws, insulators, switch)
Restore receiver.
Restore transmitter.
Make a power supply.
Find suitable accessories (headphones, key, mic, aerial)
Write a manual.

RADIO CONDITION

The radio is generally in good condition electrically.
The case is poor and coming apart.
It is very dirty and contains a lot of dust/dirt/grass.
Receiver looks complete.
Transmitter is missing valves.
Some labels missing off the front panels.
Front panels dirty.
Dials seized.
No circuits.
No power supply or batteries.
No microphone.
No morse key.
No headphones.
No transport box or case.

NAMEPLATE WORDING

Short-wave Transmitter-Receiver
Designed by Don B. Knock VK2NO
Manufactured by
Sterling Radio Pty. Ltd.
June 1937

PHOTOGRAPHS

RESTORATION LOG

July 2004 first phone request.
"Will someone restore a radio receiver/transmitter used on the Mackay expeditions".
Radio belongs to Dick Smith, was donated by the Mackay family.
It will be displayed in the Dick Smith museum.
2005 radio received.
15 July 2005 photographed.
7 December 2005 gluing and clamping all the woodwork (photo).
Got some tracing paper, and traced the VLU legend, so that I can repaint it later.
3 January 2006 sanding all the woodwork.
January 2006 painting over hand notes with clear lacquer to protect them.
February 2006 painting pink primer (photo,  photo1,  photo2).

July 2006 documentation supplied by Marilyn.
The typed description mentions UX199 valves, a filament control,
and broadcast band radio stations, so this description is not for this set.
The Australian Radio News article has a photograph of a transmitter,
probably the airborne transmitter. It has 201A valves in it.
The set I am restoring is a ground transmitter and receiver.
One point of interest is the photo of H. K. Love of the RAAF (2nd from left).
He went on to form Kingsley radio which made the famous AR7 receiver in WW2.
The SMH photograph is not good enough to show the radio,
but there appears to be a "coffin" style box with a side knob, balanced on top of the stores.
The nameplate inscription is useful.
The last two handwritten pages are a biography, presumably of MacKay.

Inside the radio was pinned a small piece of paper with some frequencies
scribbled on it. When I turned it over, it was a business card.
It says......

Don B. Knock
14 Yanko Avenue,
Waverley NSW
phone FW 2443
Experimental Radio VK2NO
Portable Radio VK2NU
Radio Editor "The Bulletin"
252 George St
Sydney NSW
Phone B 7971

His callsign has been reissued, so there is no help there.
There are Alphabetical phone numbers, and the need to have 2 call signs will help with the date.
The Bulletin magazine may be able to help with more information.
I emailed them, but they can supply no information.

There is some information on these web sites.......
http://www.austehc.unimelb.edu.au/guides/morr/MORS0011.htm
http://www.asap.unimelb.edu.au/bsparcs/biogs/P000657b.htm
http://www.jstor.org/view/00167398/ap020504/02a00050/0
http://www.radiold.com/radios/radrare/radrare03.htm

The journal entry and map talk about a 1930 expedition, but the radio is labeled 1937.

6 September 2006 started work on receiver.
The receiver is in good condition, underside very clean, top side good,
no doubt due to being housed within the cabinet undisturbed, and covered,
so that no dirt could get in, but there was some grass inside.
The components are clean, and the wires are in good condition.
Front panel is corroded, dials have red dirt in them, they are seized, and missing knobs.
The front panel is missing half the labels.
I removed the dials for cleaning, 2 knobs are missing, 2 knobs are present.
One tuning capacitor is loose, I adjusted the friction, being careful to avoid a short circuit.
I tightened several screws as the coils were loose.
The coil wire windings are cotton covered wire, but not lacquered.
I considered fixing/sealing them with lacquer, but decided not to. Maybe later.
I traced out the circuit, and it appears to be a regenerative detector, with one AF amplifier,
and one RF amplifier. I checked the resistors and they all are within tolerance.
I looked up the valve characteristics and they have 2 volt filaments.
I applied 2 volts DC, and switched ON, the filaments drew current, which is a good sign,
it means no one has burnt them out.
The AF amplifier has uses a speaker transformer as a choke, and has a phone jack,
with a capacitor from the AF amplifier plate, which means it requires high impedance headphones.
I'll look for a pair of high impedance headphones.
To test the set, I used some low impedance headphones connected to the
speaker transformer. I applied DC to the HT and negative wires (it uses back bias), slowly winding it up to 90 volts.
I could hear some noise when adjusting the tuning capacitors (they will need some lubrication).
The set oscillated when I turned the reaction control up, a good sign, it means at least two valves are working.
I connected an aerial, but not much happened. I advanced the HT to 125 volts, and heard a station.
The controls are touchy without the vernier drives attached.
The set is also microphonic, which is common with filament valves.
I used a signal generator to determine the frequency coverage, which is 4.75 to 13.7 mhz.
I lubricated the capacitors and potentiometers.
Its amazing that it works, with its original paper capacitors.
Next step in to clean the verniers, find some knobs, clean the front panel, test the sensitivity.

9 September 2006
I have cleaned the verniers and they came up nicely.
There is some wear on the bakelite around the knob shaft so it may be sloppy.
I was donated 2 knobs which are close to what should be there.
The centre bakelite cover for the main shaft has gone brittle with age.
I polished the front panel on a buffing wheel, but cannot remove the deep pitting and corrosion.
I cleaned the front panel in warm detergent, then etched it with sodium hydroxide (Draino).
I then anodized it in sulfuric acid (battery acid) at about 2 amps.
The panel came up nicely, but the pitting has been emphasised greatly.
So that is no good.
I sanded it with steel wool, to remove the anodizing, and then sprayed clear lacquer on it.
That is the best I can do, as I do not want to replace the front panel.
It has a score mark and a couple of elongated holes, which means that this was a "one off"
and possibly made to a time schedule.
It will look as though it has been out in the "outback".

Got an email from Marilyn asking about progress, so I gave her the URL of this website.
Got an email from Dick Smith, who appears happy with the progress so far.

November 2006
I tried several paint store for the correct grey colour,
finally settled on a grey spray can from Bunnings, bought 6 cans.
Began spraying the panels, one side at a time, waiting a day, turning them over then doing the other side.
Some needed 2 coats, a week apart. Came up reasonably.
Found some new brass hinges and screws, and some new eyes for the latches, but no hooks.
Searched the net as well. Finally had to spray the original hooks gold, and use them.
I made up a new VLU legend from the transfer paper, scaled it to size using the tracing paper, an applied it.
Clear lacquer to protect it.
Screwed in the hinges, attached the front opening panels and the top, then added the latches.
Wooden case is now complete.

9 January 2007
I started on the transmitter and cleaned the dirt from the chassis.
I removed the front panel, and cleaned the dirt off it with detergent.
I scrubbed it with wire wool and lacquered it. I did the same with the brass nameplate.
I cleaned and wire wooled the brass meter bezels. Front Panel (676k)
The four ORMOND dials were corroded and seized. I disassembled them (each dial had 11  parts),
and cleaned and lightly oiled the bushes and bearings and knobs.
Disassembled Dial (639k)
The dial graduations were silk screen black lines and numbers onto a gold painted scale.
The scale was corroded and the markings hardly legible. I sanded the dials scales smooth, and painted them gold.
I made a new dial scale on the computer, and laser printed it onto "Waterslide Decal" paper.
Available from BELL INC. 10319 N.W. 30 Street, Suite 103, Miami, Florida, 33172, U.S.A.
The cost is US$36 for 50 sheets, which is about $1.30 a sheet.
I cut these out with scissors, soaked them in water, and applied them.
They had to be semicircular, not an annulus, as the scale is convex, and the decal needs to bend a little.
I then applied a thin coat of lacquer to protect it. Do not apply it too thickly, or it will attempt to dissolve the decal.
Two thin coats may be required. Dial Scale (550k)
I reassembled the dials, then mounted them on the front panel.
The rusty screws were cleaned, and the heads lacquered. Any spare holes were filled with a screw.

The front panel has small labels, which are stuck on to the front panel, near each control. Some were missing.
They appear to be a metalised label with a photographic or inked legend. They look like Scotchcal labels.
This 3M product was replaced by Dynamark, which used a different developer,
which was then replaced by Dynamark II (a plastic based label), which also a different developer.
The label surface coating was exposed to Ultraviolet light through some artwork, and then the developer
was used to remove the unhardened areas, and this left the legend displayed. It was then cut out and glued to a panel.
Scotchcal, Dynamark, and Dynamark II are no longer available.
There is a new product called "Adressotak", which is a metalised adhesive backed label,  availablein silver or gold.
It is easier to use. It comes from Italy and is 133 Euros for 50 sheets, which is about $3.75 per sheet.
Prepare your artwork on a computer. Print it on the laser printer, and feed in the Adressotak paper.
Cut it out with scissors, peel off the backing, and the self adhesive label just glues on. I prepared the artwork as per
the original legends, and made guesses as to what the missing ones might have said. I printed these out and stuck them on.
Good result, close match to the originals.

1 February 2007
I traced out the transmitter circuit.
Appears to be a pentode crystal oscillator, with a  plate current meter for tuning.
The power amplifier is two valves in push-pull.
Single valve modulator.
The construction is generally good, some parts are well made and constructed.
The oscillator section is shielded and nicely laid out and spaced.
The coils plug in on 4 pin bases, one for the oscillator cathode, and one for the oscillator plate.
The oscillator cathode coil is enamel wire covered in lacquer. The plate coil is made of cotton covered wire,
but the original enameled wire leads to the base are still visible, which means that it was originally enameled wire,
and his has been cut off and it has been rewound. The grid coil for the power amplifier has had the same treatment.
The coupling from the oscillator plate coil is a 2 turn link winding, which feeds through the shield
to the power amplifier section. The grid coil has an identical link. The links are nicely made and laced.
There are several extra holes in chassis which are not used. Many holes have not been de-burred after drilling.
Some construction scratches.
The tank coil is mounted on tall posts, and is wobbly and flimsy.
The oscillator and power amplifier sockets are on short posts,
mounted above the chassis so they will have good shielding from the circuitry below.
The modulator valve is mounted in a hole in the chassis.
The power amplifier valves are too close to the tank coil, actually resting against it.
The tall chassis mounted electrolytic capacitor, the older wet type, is also too close.
It has dried out. The label had fallen off, so I glued it back on.
The tank tuning capacitor, is a different type to the other three tuning capacitors,
and looks second hand, has some bent plates, so perhaps it has been changed.
The tank coil connections to the capacitor are loose, one had no nut.
The shaft wiper and the shaft coupling both look home made.
One of the coil mounting tags sticks out, as though it was added later, or is the wrong size.
The capacitor shaft rubs on the tall electrolytic capacitor.
The HT bypass capacitor is a tall tube with wax sealed ends, held to the front panel by clamps.
It looks home made. I measured it and it was only 25 pF, very strange.
The lower pigtail passes through the chassis via a rough un-burred hole,
and was floating, that is, not connected to anything! It should have been earthed.
This appears to be a construction error. Maybe it was touching the hole when it was first made.
Maybe it was intermittent, which may explain the dodgy look of the tank components.
When I connected it to earth, the capacitor value read as 0.25 uF, which was much better.
It did not change the resonant frequency of the tank coil, which is 5.2 to 11.1 mHz.
The oscillator cathode coil frequency is 3.4 to 9.8 mHz, which was indicated on my GDO.
The oscillator plate coil did not dip at all. There was a place on the coil where two wires were
twisted together, so I soldered them, and it now dipped at 6.0 to 10.0 mHz.
The power amplifier grid coil was 5.0 to 8 mHz.

The transmitter had no valves, so I had to identify the types.
The Power amplifier used a 7 pin UX base, with a plate top cap.
The 807 valve has 5 pins, so it wasn't that type. The 1625 has 7 pins, but was made after 1937.
That left the 802 valve, which matched the application and physical dimensions.
This means that the other valves had to be 6.3 volt filament types.
The oscillator valve was octal based, and
the pin connections matched the 6V6, 6F6, and 6L6. The 6V6 was lower power and was available in 1937.
The modulator valve was 6 pin UX based, 6.3 volt filament, has a grid top cap, and had to be an audio power valve.
The only candidate was the 89. I had none so I ordered one from Melbourne. I had the other three valves in my junk box.

The modulator valve is cramped into one corner. The microphone transformer and modulation transformer
are mounted under the chassis, and poke down too far, such that the wooden partition below the transmitter,
has two square rough cut-outs for them. It all looks like an after-thought. Perhaps it was added later.
I added a 10uF 600v electrolytic capacitor across the defunct large tubular vertical electrolytic capacitor,
under the chassis. I removed the modulator cathode bypass capacitor, and put a new 25uF 50 volt
electrolytic capacitor hidden inside the old cardboard case.

I tested the transmitter. There was no crystal in the holder. It is a bakelite holder, with two brass plates
held down with a spring clamp. The slab of quartz was missing. I added an FT243 crystal with alligator clips.
I connected a 12 volt 25 watt light globe to the aerial terminals.
I powered up the heaters with 6.3 VAC, and they all seemed to glow appropriately. 
I then applied 100 volts DC and the plate current meters showed a little deflection.
There appeared to be no short circuits. I slowly increased the voltage in 50 volt steps to 300 volts.
I monitored the plate current and dipped the meters with the four tuning controls.
The meters are very lively and would benefit from some damping. They wobble all over the place
so finding the dip is difficult and time consuming. The light globe was glowing.
It all appeared to be working, and the morse key keyed the transmitter properly.
The PA plate current began to rise, for no apparent reason, so I switched everything off.

I looked in my junk box and extracted a high impedance set of headphones for the receiver.
I extracted an early morse key for the transmitter. I do not have a suitable early carbon microphone.

The radio uses an external power supply, connected by cables to a sockets on the case.
The receiver has a 5 pin UX type female socket.
I got two suitable plugs from my junk box
and plaited a cable from some old style cotton covered wire,
and attached the 5 pins plugs to each end.
The transmitter uses two 2 pin male sockets of a type that I have not seen before.
I examined my junk box and found two that were a close fit, bit wrong pin spacing.
I removed the pins and elongated the holes, such that the pins matched, then glued them in place.
One has a key, so that it can only be inserted the correct way, and it also can not be confused with the other.
I plaited a cable from cotton covered wire, to connect these two plugs to a 4 pin UX plug.
The keyed plug is the 500 vDC and the unkeyed plug is the 6.3 vAC.

There was no power supply provided with the radio, and there was no indication what it might be.
I guess that the receiver would operate from batteries.
The filament battery would probably be a single lead acid cell providing 2 volts at 0.5 Amp.
The high tension would probably be a dry battery providing 135 volts at approximately 15 mA.
The transmitter requires 6.3 volts at 2.5 Amps, so this would probably be three lead acid cells.
The high tension would be somewhere between 400 and 600 volts at about 100 mA,
which would probably be supplied from a 6v dynamotor.
I decided to build a mains power supply, to generate these voltages.

I took the radio to the Wyong Field Day on the 18th February 2007 and displayed it there.
I had planned to have it operating but I had not completed the power supply.
A helicopter arrived and Dick Smith came over to have a look at the radio.
He seemed happy of the restoration effort so far.
Radio on display (64k)
Dick Smith examining radio (45k)

20 February
I used an old instrument case to build the power supply.
It has 2 sockets on the front, a  4 pin socket for the transmitter, and 5 pin socket for the receiver.
It has separate mains ON switches, fuses and indicator lamps, and ouput sockets,
so that each supply can be used independently.
I painted the power supply front panel, and finished constructing the filament supply.
It consists of a type 2155 transformer, which is 240 VAC input and a multi tapped 15 v secondary.
I then adjusted the taps, to get the correct output voltage.  
It uses a diode bridge rectifier.
The filtering is a choke with 2 large capacitors.
I began writing up the restoration description.

1 March
Finished the receiver power supply, but there was too much hum.
Not enough filtering on the DC filament supply.
The choke and capacitor filter had too much ripple on it.
I used two high power diodes in series, to provide a 2 volt zener regulator.
This heated up after about 5 minutes, and the 2 volts drops to 1.8 volts,
this appeared to make no difference to the receiver.
The hum was still just audible but not obtrusive.
I finished the receiver high tension circuit.
This is another type 2155 transformer, but connected reversed,
so that the 240 volt input winding, is the secondary.
Then I connected the 15 volt output of the first transformer
to the 6 volt tapped winding on the second (reversed) transformer,
thus achieving a 120 volt secondary.
It uses a diode bridge rectifier with a choke filter and 2 capacitors, and a 10k 2 watt bleed resistor.
The receiver was now not working!
It had failed since my initial testing.
The reaction coil has a tap which is twisted together, and this had gone open circuit.
I soldered it, and the radio worked well on the new power supply.

15 March
I began on the transmitter power supply.
I used an old large mains transformer, suitable for field coil speakers.
It had 385 volts aside, and a 6.3 volt filament winding.
When rectified with silicon diodes, and a choke and filter capacitors, it produced 500 volts DC,
probably under running the final valves a little. There is a 27k 5 watt bleed resistor.
Finished the transmitter power supply.
I powered up the transmitter heaters, and the power supply appeared fine,
until one of the filer capacitors went short circuit. I replaced it.

19 March
Finished the article on Donald Mackay's life and the expeditions.

23 March
I powered up the transmitter with 500 volts DC,
and it appear to work well into a light globe dummy load.
The current meters do not read full scale, indicating that it may have been designed for 600 volts DC.
The oscillator tuning control can pull the crystal a little,
and it will also oscillate without the crystal, so it can be used as a VFO.
The oscillator meter can be dipped with the second control.
The third control is used to provide drive to the final and is tuned for maximum plate current.
The 4th control is the tank circuit and dips the final meter.
After 5 minutes, the plate current began to rise again, so I turned it off.
The long bakelite cylinder behind the panel was hot.
This is the final HT bypass capacitor. The wax was melted off,
and the internals removed. It consists of two 0.5uF 600v capacitors in series.
They were replaced by one 0.25uF 1000v capacitor, and put inside the original Bakelite tube,
and the ends sealed in wax. This has fixed the problem.
The transmitter appears quite reliable.
It generates several harmonics, but if the transmitter is tuned normally,
the harmonics are 40 dB below the fundamental amplitude.

1 April
The circuit is hand drawn, so I decided to use Protel to draw it neatly.
Protel only has transistor, IC, and passive components,
so I had to design some valve building blocks for the library.

13 April 2007
Wrote a short article about decals.

28 May 2007
Finished the Protel valve library, and drew the receiver circuit.
Receiver circuit.

June 2007
Drew the transmitter circuit.
Transmitter circuit.
Not sure what those 2 wires do on the modulator suppressor grid.
Perhaps they can be connected to a plug then plugged into the microphone jack.
This will make the audio amplifier oscillate and  produce MCW.
That would justify the reversing switch which reverses the wires.
But why is this not done internaly.
Why are the wires so long, the ends are bare, not soldered, and look as though they are for connecting to terminals.

November 2007
Collected some more information on Don Nock from articles in Wireless Weekly, from Brian Gall, Max, and Ian Bourke.

December 2007
Received an email from Marilyn asking about progress.
I explained i had been sidetracked by other projects,
but had been planning further work.
Suggested she look at this log to see the latest progress.

January 2008
 Realised that the microphone picks up voltage from the transmitter heater circuit, so it must be a carbon microphone, but what type. I have no 1937 vintage mics suitable. Will have to ask someone. Also realised the transmitter heater voltage should be DC instead of the 6.3 volts AC that the power supply was delivering. I was trying to use no active components in the power supply, but it was now obvious I needed to use a regulator IC. Will have to redesign the power supply. Might as well redesign the receiver filament supply as well, so used an LM317 regulator IC which supplies 1 amp, and set it up for 2 volts DC. Receiver draws 0.5 Amps. Used a LM350K regultor IC in a TO-3 case and bolted it to the chassis as a heat sink. Set it up for 3 Amps DC at 6 volts. Transmitter draws 2.65 Amps. There was not enough voltage available from the 6.3VAC winding on the transformer, so connected the 5VAC winding up as well. A problem here, as the transformer has an internally earthed centre tap, so I connected them in an unbalanced series mode. Power supplly appears to works fine.  Labels were lifting off the power supply front panel, so I put new ones on.

Tried the receiver with the new DC filament supply. It now has no "mains" hum, but has some "grid" hum. This is bearable. Very microphonic, with occasional loud clicks. Drops in and out of regeneration suddenly.

Tried the transmitter with the new DC heater supplyand it seems fine. Voltage sags when the transmitters cold heaters are turned on, but then reaches operating voltage as they warm up. Oscillator works OK, works too well, oscillates, even without a crystal. Maybe the leads are too long as I had the crystal clipped in with alligator clips. I pulled my FT-243 crystal apart, took out the quartz slab, and put it into the orginal holder, which is a bakelite holder with 2 brass plates and a tensioning spring. No diffeernce,
still oscillates anywher and pulls with the oscillator tuning. The tuned circuits only tune from 5 to 10 mhz, so I assumed the crystal would be in this range, and I was using a 7.025mhz for the 40 meter amateur band. Then I realised my mistake. The holder has 3340 scratched on it, and the second control is labeled DOUBLER. I should be using a crystal at half the transmit frequency. I found a 3.540mhz crystal from my junk box, put it in with alligator clips, and the VFO is perfectly stable, tunes up nicely, and transmits on 7.080mhz.

The morse key is in the final amplifier cathodes, so the oscillator does not pull or chirp. When tuned, the transmitter lights up a car light globe as a dummy load. Tried a WW2 carbon mic and it modultes the carrier OK, but it looks a littel ragged on the CRO. Will have to test further.

I connected the 2 unkown wires to a jack plug, plugged it into the mic jack, and switched the switch back and forth, while watching the modulation, it won't oscillate.

I have been trying to find out who owns the copyright on the photos in the Frank Clune book. The publisher Angus and Robertson does not hold the copyright. I contacted Frank Clune & Son Pty Ltd, and they do not hold it. Frank Clune and his son have both passed away. I contacted VISCOPY and they don't hold it. I contacted the Arts Law Centre of Australia and they don't hold it. I contacted the Austraian Copyright Council, and they directed me to their web page (http://www.copyright.org.au) which has information about Australian copyright laws on it. Sheet G23 says that the copyright on photographs taken before 1 May 1969 lasts 50 years. The photos wrere taken in 1937 and the book was published in 1942, so they are in the public domain from 1987 or 1992, depending on which year you choose. I can now send off the article to the HRSA Radio Waves magazine.

21 January 2008
My 40 meter aerial had fallen down in the summer storms, so on one of the few fine days on the weekend, and I put it back up again. Tuned up the aerial on 7.080mhz and gave a few calls on CW and phone, no replies.

22 January 2008
Tried again  with VK2ZIO listening at Kurrajong and he heard me, despite the competeing Chinese RADAR signals. A wonerfull effort for an old transmitter. He couldn't hear my phone signal, just the carrier. More tests needed here.
On-Air recording (6mb wav file)
On-Air recording (6mb wav file)

Transmitter was incorrectly labeled as I had made a guess from the switch function, and what labels remained. The two right hand switches were labeled from right to left, OFF (switch) CW, (switch) PHONE (microphone gain control). The right hand  switch turned the heaters on and off, so I changed CW to ON, and added a FIL. VOLTS label above it. Still not sure what that second reversing switch does, but it was labeled PHONE, so I left it this way.

My wattmeter says 10 watts, but I think it is capable of more that that. I read the 802 (final valve) data sheet, trying to figure out what it can deliver. The maximum ratings are, plate 500VDC at 30mA,  screen 200VDC at 28mA,  plate diissapation 10 watts. This has 530 VDC and when tuned shows 50mA for the 2 valves, so this appears correct. It also implies that power output should be greater than 10 watts. The data sheet also gives grid bias and suppressor grid conditions for class A, B, and C, and  for audio,  RF, CW and telephony. The "grid leak" bias resistor is as recommended. The suppressor grid can have 2 different connections, depending on use. It can be grounded or connected to cathode as is normal. But more importanatly, it can have -40 VDC on it for telephony, or +40 VDCon it for CW. Finally, the use of those 2 wires and the switch becomes apparent. It needs a bias battery and uses the reversing switch! So now I will redesign the power supply to add a 40 volt floating supply and connect it up.

February 2008
Fix phone jack, it was too long, so I shortened it.
Make bias battery and connect somehow.
I added a 50VDC floating supply and added termianls to the power supply, seems to work OK.
Sent the Donald Mackay biography article to Radio Waves.
Delived the radio back to Dick Smith. He donated it to the Powerhouse museum.

March 2008
Power supply circuit completed.
Power Supply circuit

STILL TO BE DONE
Get a mic, I don't have a suitable type.
Write an operator manual.
Write a short article about Scotchcal.
Write a biography of Don Knock .
Write a biography of Sterling Radio.

end