Farmers Unite!!
 

Was tinkering around today and put together a simple power supply for the forgotten farm radio. I'm sure a us lot of have one or two of these set that haven't been turned on in years, lots of years. One of mine is a Crosely 2V Fiver I got back in the '70s. Back then it had a few problems including a bad osc coil. Fixed it all up and it's been sitting since. Thought I'd take her for a spin hence the power supply. The HV is a typical AC/DC design.Was able to get 130V under load. The A voltage is provided by a 6.3v transformer, bridge rectifier and adj ic regulator. It will deliver up to 8v @ 1.5A which is adjustable down to 1.2V. A lot of the parts I scrounged from some old computer p/s and from the junk box. Most of them are not very critical.

Let's make January farm radio month. Dust one off or if you don't had one get one. And get her going!
Terry

Very nice :thmbsp:
I have an old Philco 643B farm set that was converted to AC operation by a hack long, long ago.
I think I'll strip it down and restore it to DC operation one of these days :scratch2:

What qualifies a radio as a farm radio?

John

A farm radio is a battery-powered set. A lot of these were used in rural areas as many rural homes were without electricity, some up to the mid-50's.

Well I'd say made from early 1930's thru mid '50's. Most will uses Battery type tubes 1.4v or 2.0v with low current consumption like 50ma. Has no pilot lamp or it will have a switch to turn it off and on. No handle on the top. May be powered by a wind-generator or 6v car battery/vibrator.

Terry

I need to cobble together a good power supply one of these days. I built a kit from AES in the 90s but it never worked right and I finally junked it. My lack of understanding of solid state circuits doesn't help.

I do have at least a couple farm sets that I have brought back to life. One is a Sparton, the other an Airline. I have some batteries I've built in cigar boxes for when I want to play with them. Recently I aquired a neat set, another Airline that is a convertible so that when the REA came to the farm it could be switched from battery to AC with a flick of a switch. (at least, I guess that is how it works-I haven't dug into it yet) I have picked up some respect for these farm sets. Usually a nice, big cabinet on the table models, but with just a tiny chassis. Good thing is that chassis makes them easy to work on.

Excellent idea! I have an L 'Tatro I picked up ages ago because I liked the small simple dial and the history of the company being from Iowa. It will be fun to work on something different like this 6 volt farm set, plus maybe it will give me a chance to verify the colorful history of the company as it was once told to me.

I have a 32V Philco I picked up at a farm auction for a buck (only bidder!) but I've never played it due to its odd power requirement. Probably should cook up something to remedy that. I've run across 32V appliances (mixers, fans, etc) at farm auctions as well. Evidently some windmills were 32V, along with the DelcoLite plants that were in use in those pre-REA days.

electronjohn,

Does your 32V farm radio employ a vibrator to generate B+ for the tubes , or does it use low voltage tubes that can function with a B+ of only 32 volts?

jr

Think it might be a vibrator...I'll have to dig it out of storage to be sure.

The DC farm radios like the Philco Models 48 and 49 did not have a vibrator. The filaments were in series with the speaker electromagnet and usually a ballast. The tubes ran directly off low-voltage DC. Some of the supply voltages in some makes of radio were 32 VDC.

I'd be happy to get some sort of rig to fire up & try my '27 Grebe Synchrophase...I THINK it has 3 different voltages....

Ditto on my Philco 643. There is an A, B & C battery. I think the A is filament, B is plate and C is bias.

I may be all wet here, but I think remember reading about a "mobile" version of the R-390 that used low plate voltage tubes.... I can't imagine that it would perform as well as a standard R-390 or R-390A... anybody here know how well it worked? Would it qualify as a "war farm" radio? :)

jr

It's called an R-392, & it used a 28VDC military supply...I have a Collins example that uses a modified AC supply, & it works great...They make dandy camp stools, & get nice & toasty after they've been running awhile...You could also use one to hold up a corner of a Jeep if you wanted to change a tire, the cases are THAT tough...Supposedly, the cases are waterproof, & the radio reportedly will operate underwater, but I ain't ever been THAT brave/foolhardy.

Did it use a motor generator set?

John

Not sure. Apparently, jeeps & other military vehicles back then put out 24-28VDC instead of the 6-12VDC civilian vehicles did...An R-392 will work w/24VDC, but just not as well...They're roughly similar to the size of a case of 8.5 X 11 office paper, & weigh 55lbs, & have 2 handles on the sides...The ones I've seen can be kinda scuzzy on the outside, but usually look brand-new inside, since they are "sealed"...Most of the tubes are common, but there's one audio tube that's a bit odd...Sometimes they're found w/a SS audio module, but it is virtually identical to the tube in output & fidelity..They're maybe not quite as "good" as a std R-390 or 390A, but, OTOH, I've never really hooked mine up to anything more involved than a length of speaker wire for an antenna...And they DO seem to be somewhat more robust than a 390...I even have the matching transmitter, a T-195.

Nice! I found this about the R-392:

"It operates from 24-28 volt DC power with no vibrators, dynamotors or other voltage converters."

http://www.roveroresearch.org/r392/r392.html

Add: oops, I see the site lists one for sale, so I guess I should add "not affiliated".:o

jr

Pulled out one of my favorite farm sets to take her for a spin. It's a Philco 37-33 I got back in '87 in Kentucky at a radio swap. It was a mess rusty, no dial scale or speaker. The speaker was interesting because it connected directly to the output tube which in this case is a 1E7 dual pentode wired for push pull operation. So the speaker had a center tap. Anyway it got replaced with an eight inch Jensen w/matching transformer. Chaiss got cleaned up and a coat of black wrinkle, back then couldn't get hammertone and a repro dial was found for it. Refinished the cabinet and touched up the flash finish front panel. When it was finished it worked great! The 1E7 will make about 1/2watt of audio. Doesn't seem like much but it's plenty loud and very clean. The whole set draws 15ma B+ and .5a @ 2v. The picture of the speaker is from ebay as one was just sold a few days ago. (not mine)
Terry