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 Post subject: 32 volt radio
PostPosted: Sep Mon 01, 2014 3:11 pm 
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Joined: Nov Sat 19, 2011 3:16 pm
Posts: 263
Location: Lipan, Texas
Hello all. I have acquired a 32 volt Silvertone along with a few other radios from a local auction.
Its not on the bench yet but ive started looking for a power supply. Would appreciate yalls feed back on this item
C:\Users\jack\Desktop\HP AC Adapter C8124 60014 Power Cord Input 100 240 Volts Output DC32 eBay.htm
I haven't tested tubes yet but hoping since this came from a knowledgeable restorer( passed away) and
it had a tag on the cord denoting 32 volt radio that theyre okay. Fingers crossed!
All feedback and advice appreciated.......Jack


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 Post subject: Re: 32 volt radio
PostPosted: Sep Mon 01, 2014 3:56 pm 
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Here's a listing that probably includes the one you saw:
http://www.ebay.com/sch/i.html?_odkw=et ... p&_sacat=0

We need to know the current requirements on your set---if nothing else, tell us the model number

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"Measure voltage, but THINK current." --anon.


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 Post subject: Re: 32 volt radio
PostPosted: Sep Mon 01, 2014 4:13 pm 
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Some 32 volt radios have a pair of 48 output tubes. These radios may have a regular AC plug on the cord. Hopefully no one has plugged it into the AC line. Both 48 tubes will blow almost instantly.

There are surplus 24 volt power supplies. Some can be adjusted to just about 32 volts. Radio will operate with a little less voltage.

Don't try using a switching power supply. Noise generated will be hard to eliminate.

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 Post subject: Re: 32 volt radio
PostPosted: Sep Mon 01, 2014 5:59 pm 
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Joined: Nov Sat 19, 2011 3:16 pm
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Location: Lipan, Texas
Silvertone M-4429. Yep, checked the 48s, actually one of them was a 43 and alas both were blown. Didn't see much on e-bay for 48s.
Assuming its going to be a fairly expensive tube?


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 Post subject: Re: 32 volt radio
PostPosted: Sep Mon 01, 2014 6:15 pm 
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Location: Detroit, MI USA
Yes, it has become expensive and hard to find due to stupidity.......as Norm pointed out the plug looks exactly like a regular AC plug and people can't read. Instant flashbulb time........then they still don't realize what they just did, and put the radio away never to work again.

You can use a pair of 43's, the set will work just fine and a lot of people are doing exactly that. But you need to keep the supply voltage below 32 if you go in that direction, or add a dropping resistor for the 43 filaments. You start to lose sensitivity if you run the set on a supply very much lower than about 30 volts. These sets also need a good antenna and ground connection to work best.

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 Post subject: Re: 32 volt radio
PostPosted: Sep Mon 01, 2014 7:23 pm 
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Add a 25 ohm @ 5w resistor in each 43 heater line and you can run it on 32v as designed...


Tom


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 Post subject: Re: 32 volt radio
PostPosted: Sep Mon 01, 2014 7:55 pm 
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Joined: Nov Sat 19, 2011 3:16 pm
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Location: Lipan, Texas
Thanks guys. Ill probably do the 43s with resistors. Back to original post, any recommendations on power supply?
......................Jack


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 Post subject: Re: 32 volt radio
PostPosted: Sep Mon 01, 2014 8:09 pm 
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Something with an old fashioned conventional iron core power transformer (heavy) and a couple of rectifiers and a filter network inside as opposed to a modern switching supply. You could certainly try a printer supply that puts out 2-3 amps if you already have it and see what happens, it isn't going to hurt the radio. But I wouldn't buy one just on speculation, because others have reported they are too noisy. It's also possible there is one that isn't noisy, if it's from an old enough printer and uses a conventional circuit design.

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 Post subject: Re: 32 volt radio
PostPosted: Sep Tue 02, 2014 12:32 pm 
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jackedup wrote:
Thanks guys. Ill probably do the 43s with resistors. Back to original post, any recommendations on power supply?
......................Jack

I'd look for a transformer ~30 to 36 volts RMS (0r 2X that with a centertap)
Add some diodes, filters, and maybe a simple emitter-follower regulator*. If you'd like to pursue this, I can noodle up a schematic later.

Do we know the current requirements?


*You can always "brute force" it with a series resistor to get the right voltage. The supply does not need to be regulated

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"Measure voltage, but THINK current." --anon.


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 Post subject: Re: 32 volt radio
PostPosted: Sep Tue 02, 2014 1:28 pm 
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pixellany wrote:
Do we know the current requirements?



With a pair of 43 at 300 ma each and the other tubes at 300 ma for string, I'd think 1.2A should be more than enough... If there's a dial lamp that would need to be added but still 1.2A-1.5A should handle the total radio... If you're going to use 48 then 1.5A would probably be a minimum...


Tom


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 Post subject: Re: 32 volt radio
PostPosted: Sep Tue 02, 2014 3:32 pm 
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Location: n9842 n birch rd, tomahawk, wisconsin, 54487
I've had several 32 volt radios and they all ran fine on as little as 24 volts. You have to remember that they were engineered to operate in a wide range of voltages. The old wind generators and Delco Light power plants charged the 32 volt battery bank as high as 42 volts if the batteries were reaching the end of their life. Your radio only draws about one amp so three small 12 volt gel cells in series for 36 volts would be perfect for your set. Recharge each with a small 12 volt charger. I've run both a Delco and an Airline set both on my 36 volt battery bank in my GE ElecTrak garden tractor. No problem.


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 Post subject: Re: 32 volt radio
PostPosted: Sep Tue 02, 2014 6:13 pm 
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^^maybe the best idea yet^^
Note that Home Depot has some good prices on small 12-volt batteries for garden tractors

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-Mark
"Measure voltage, but THINK current." --anon.


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 Post subject: Re: 32 volt radio
PostPosted: Sep Tue 02, 2014 6:50 pm 
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But would you really want to invest in 3 batteries dedicated to one radio, which are going to cost more than the radio itself is worth? That doesn't seem very practical from an economic standpoint. If one had a collection of several 32 volt sets, it could make more sense.

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 Post subject: Re: 32 volt radio
PostPosted: Sep Tue 02, 2014 9:02 pm 
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As you suggest, "it depends".......I have a growing inventory of battery sets ( no 32-volt yet), and I have noodled a bit on how to build a universal battery eliminator. I would have no problem making this into a big-deal project.....;)
For something specific like 32 v, what are the options?

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"Measure voltage, but THINK current." --anon.


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 Post subject: Re: 32 volt radio
PostPosted: Sep Tue 02, 2014 11:14 pm 
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pixellany wrote:
For something specific like 32 v, what are the options?


Moderate rewiring of the unit to include a AC P/S that supplies B+ similar to a AA5... Using 43, all tubes are 300ma so could be in series...

A pair of PP 48 running at 32v only produces 150mw & I suspect it's less for 43... Most of the issue I see would be does the PP output xformer have the current capability to operate a pair of 43 at 120v B+?? If one ying-yinged a PS so B+ was say 75-90v it'd be a far better performer than at 32v...

No it wouldn't be safe if it were in my possession...

Tom


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 Post subject: Re: 32 volt radio
PostPosted: Sep Tue 02, 2014 11:36 pm 
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Tom, you could definitely go there. I have seen a few 32 volt sets which were converted to series string and 120 VAC operation after the power lines were extended out into rural areas. Owners were thrifty and would sometimes rather pay a shop to do a conversion than go out and buy a new radio. Last one I had used a 25Z5 (in a rewired 48 socket, as rectifier) and only one 43, with an added dropping resistor for the tube filaments.

It would be relatively simple to rewire all the filaments in series and run the set on something like 70 volts or so DC with 43's in the output.

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Dennis

Experience is what you gain when the results aren't what you were expecting.


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 Post subject: Re: 32 volt radio
PostPosted: Sep Wed 03, 2014 8:30 pm 
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I can't take credit for this one - a great hint from others here on ARF in the past:

http://www.ebay.com/itm/HP-AC-DC-Adapte ... 2ed61587f3

These powered old HP printers, and perfect for 32 volt radios.

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 Post subject: Re: 32 volt radio
PostPosted: May Thu 09, 2019 11:43 am 
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Location: British Columbia
An old thread but since I may have a 32 volt set in my future I did a search and read this. In my opinion I think it would be a shame to convert a 32 volt DC radio into a series string set just to operate it from mains voltage, to me that defeats the purpose of owning one. You could do something similar with a 1930s or 40s battery set, and I have heard of a few, but honestly building a power supply is easier then rewiring the whole radio, plus it's more fun getting a 70 year old radio to play as it did when it was new. The set that I am looking at is a Canadian set, a Phonola built by Electrohome, unlike many 32 volt sets it uses a class B or AB power output stage, a 6A6 tube driven by a #43, so even if someone did blow the tubes they are at least readily available, or of low demand.
I think that the most practical thing to do with a set employing #48 tubes is a mild conversion to using type #43s, or if one wished to make a six pin to octal adapter, use 35L6s. I did see a post war 32 volt set once that used a 35L6, whether the bias for a #48 would be close enough I'm not sure, but it may be another cost effective option since it would be connected in parallel across the 32 volt line, even if the current draw is only 150 ma.
Regards
Arran


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 Post subject: Re: 32 volt radio
PostPosted: May Thu 09, 2019 1:58 pm 
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Joined: Jan Wed 07, 2015 10:39 pm
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Location: Jamison PA
I have several 32v radios. With and without vibrator B+.

If you like power tools, use their batteries in series. I have makita 18v equipment. What I do is put two of them on the table facing each other, use a buss bar between one side (pos, neg) then any sort of spring clip in the slots of the remaining open sides.

Like the OP says, these will tolerate from 24 to 38 volts easily. I have 32v light plant generators, and can attest to that. They were made to run off house battery current, until it was too low, and then you used the light plant to recharge them. The whole house ran off 32v, and the plugs and wiring in the wall were in many cases the same as when the "high line" AC power made it to the farm,.

It's a cheap way to power them, and battery power will not generate that annoying RF buzz or whine that I have gotten using a 32V power supply


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 Post subject: Re: 32 volt radio
PostPosted: May Fri 10, 2019 8:28 pm 
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Joined: Oct Sun 18, 2015 2:49 am
Posts: 255
Location: San Angelo, TX
I have some 32 VDC radios and have run them off of an HP switching supply. The radios work, but the hash from the switcher is terrible, even from the vibrator powered L Tatro. Running on the batteries on my Delco Light Plant, they work great, but I use four 8 volt car batteries on it! Like some others suggested, I would go for a brute force power supply. Denis


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