I have a old military radio (ARC-5) that requires a power supply for its operation, normally provided by a generator. I have seen small torroid based power supplies that include a 2 transistor flip flop driver for the torroid that produces this.
I have since lost this article, and would like to know if anyone knows how to wind a torriod to produce the following voltages:

• +HV (High Voltage): Must be between 200 and 250 VDC
• LV (Low Voltage): This is a receiver's filament voltage.
• Three different filament voltages (25.2 VAC, 12.6 VAC, and 6.3 VAC) should be available for powering ARC-5 receivers.
• Thanks in advance for any help

 

Not sure but ARC-5 related in the CQ magazine can be helpful. You can search there. Here is also a command set. https://www.scribd.com/doc/225935431/Compilation-of-CQ-Articles-on-ARC-5-Command-Sets

 

Hello,

Does this page tell you more about the arc 5?
https://www.skywaves.ar88.net/homebrew/ARC-5_PS/ARC-5_PS.html

Bertus

 

Hello,

Does this page tell you more about the arc 5?
https://www.skywaves.ar88.net/homebrew/ARC-5_PS/ARC-5_PS.html

Bertus

Yes this is invaluable for hook up, but alas, it assumes that the dynamotor is installed and producing the voltages required

 

Hello,

Perhaps the following pages might interest you:
https://k6jca.blogspot.com/search/label/ARC-5 Receiver -- BC-454-B
https://k6jca.blogspot.com/2023/11/bringing-arc-5-receiver-back-to-life_28.html

Bertus

 

Been more years than I care to remember but my first novice rigs were ARC 5 units circa 1963. The finals are 1625 tubes having 12 volt filaments. The 1625 filaments were wired in series so we changed the final filaments to parallel and used 12 volts. Next, from memory Next you need about 200 maybe 250 volts for the oscillator and screen voltages but you will want about 600 maybe 650 volts for the final plates, the 1625 plate voltage. This is all for the ARC 5 transmitters. When I was a kid and young novice I was fortunate to live around endless surplus stores in NYC and could buy an ARC 5 for 5 bucks. The transmitters were great with a few modifications for ham use. You bought them for the different ham bands and as a novice back then could not use a VFO so my ARC 5 transmitters were modified for crystal control. While my ARC 5 stuff is only memories I still have an old R392 receiver. The ARC 5 transmitters were originally powered by a dynamotor on the aircraft they were used in.

I agree with Bertus in that old QST Magazines had articles on how to do the conversions including replacing the large coil used for antenna tuning. A Google of ARC 5 power supplies should bring up some data. I never worked with the ARC 5 receivers. You may find this useful.
Bringing an ARC-5 Receiver Back to Life, Part 2 (An AC Power Supply)

Ron

 

Years ago I used an "ARC5" receiver ,with the filaments rewired for 12 volts operation, in my car, running the original 24 volt dynamotor on 12 volts. With the car's antenna and a separate speaker it was adequate for casual listening. The 24 volt dynamotor will deliver at least 125 volts DC whenrunning on 12 volts. A couple of years later I also powered a low-powered transmitter from that same dynamotor. So the receiver and at least one transmitter would function on the lower DC supply voltage.

 

Those dynamotors run on 12 or 24 VDC. Pretty cool stuff. Running on 12 volts they has a current draw of about 13 amps. The early 60s were great for old WWII and Korean War surplus electronics. I still see them turn up on Ebay once in a long while. Today life is so much simpler.

Ron

 

13 amps is way too much for the small dynamtor og an ARC5 receiver. About 2.4 amps rated, less than two amps on 12 volts.
13 amps would be my medium high power 400 v@180 Ma dynomotor. That will gently power two 6146 tubes atless than rated power. Because running tubes hard reduces the life, and they are not cheap.

 

Many had the dynamotors (very noisy both for audio and Rf) removed and replaced with an electronic PSU circuit. Should be plenty of old articles in CQ or other ham magazines with the details available.

 

Certainly dynamotors are noisy, and much less efficient, than electronic replacements. No question about that! But they do work! In addition, they often survive accidents and abuse that would damage an all-solid state replacement.

 

Certainly dynamotors are noisy, and much less efficient, than electronic replacements. No question about that! But they do work! In addition, they often survive accidents and abuse that would damage an all-solid state replacement.

Yep, a dynamotor can take a beating and keep on ticking.

Ron

 

I just checked on one of my ARC5 receivers. The dynamotor tag reads 1.1 amps at 28 volts. The output reads 0.060 amps at 250 volts.

 

The dynamotors were built MIL-Spec and the ARC-5 also MIL-Spec designed to work with their noise but replacing them (instead of repairing them) was very common practice by hams. If I recall correctly, they were required due to the 400Hz AC frequency used by aircraft and were the kludge to solve the problem.

 

Evidently some aircraft also had 28 volt systems. I am guessing that the ARC5 equipment was used in fighters, because it is so compact. And switching radios to change frequency ranges quickly as a tactical option makes perfect sense..

 

Evidently some aircraft also had 28 volt systems.

Most aircraft have 28 volt systems in addition to 120 VAC 400 Hz. Think I spent half my career on them. Pretty robust stuff. Most aircraft have 3 phase systems on their 400 Hz.

Ron

 

Interesting about having three phase! Of course, it makes perfect sense! And the 400Hz makes all of the magnetics lighter. BUT clearly the ARC5 radios were for planes with DC systems only.

 

Actually and we are so far off topic, aircraft like the B17, B29 and others actually had huge DC generators but used that DC to drive inverters to get AC power but most of the systems onboard were DC. Pretty cool stuff for the day.

Ron

 

I assumed it was because they used 24VCD battery engine start systems and were not dependent on 400Hz VAC being generated/failed but you know what they say about assumed... I know nothing about aircraft wiring systems other than the strange frequency typically used... Yeah well off-topic!

 

I have a old military radio (ARC-5) that requires a power supply for its operation, normally provided by a generator. I have seen small torroid based power supplies that include a 2 transistor flip flop driver for the torroid that produces this. I have since lost this article, and would like to know if anyone knows how to wind a torriod to produce the following voltages:

• +HV (High Voltage): Must be between 200 and 250 VDC
• LV (Low Voltage): This is a receiver's filament voltage.
• Three different filament voltages (25.2 VAC, 12.6 VAC, and 6.3 VAC) should be available for powering ARC-5 receivers.
• Thanks in advance for any help

There is no explicit reason to wind a torroid. Once you know all of the output currents you want, you can get everything you need from purchased transformers.

1 - 25.2 V transformer
1 - 12.6 V center-tapped transformer for the 12V and 6 V outputs
1 - small power transformer with an output voltage of 80 - 90 Vac. If you drive this "backwards", with the mains connected to the 80 V winding, the primary wires will have around 175 Vac. Rectify and filter for 240 Vdc.

ak