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 32 volt radios
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 Return to top of page · Post #: 1 · Written at 4:33:30 PM on 15 January 2011.
32v Mike's Gravatar
 Location: Sydney, NSW
 Member since 15 January 2011
 Member #: 812
 Postcount: 11

Hello members,
another newbie with perhaps a different angle. Have a long time interest in Wind power history. 32 volts was a common voltage used on farm battery banks be they recharged by wind or engine power. Wanting to collect and restore 32v radios to one day run off a wind power system, I have a couple of windgens in the air but not here in the city. Badly need a member to give me tips so I avoid costly/dangerous mistakes and dont further destroy good radios. Keen to swap parts/info. Kind regards Michael.

 Return to top of page · Post #: 2 · Written at 4:56:15 PM on 21 January 2011.
Gfr53's Gravatar
 Location: Harston, VIC
 Member since 28 February 2009
 Member #: 442
 Postcount: 145

G'day Michael,

32 volt valve radios are an interesting subject in the preservation/restoration of our hobby.

Several members of the HRSA specialise in this subject, one being Greg from SA who collects and restores them and has a number of wind generators on his property East of Adelaide.

Basicaly, 32V radios are similar to their 240V ac brothers with the major differences being in the power supply.

In the early days, most low voltage radios had a vibrator power supply which used a vibrating reed to chop the low voltage DC so that it could be fed into a transformer to step up the voltage to about 180 to 250v to provide the HT for the valve anodes. Most car radios up to the 1960's used this method.

This note is getting too long for a quick reply, can you open your email address public on your profile and we can continue this on email.

Cheers, Graham...

 Return to top of page · Post #: 3 · Written at 4:55:25 AM on 23 January 2011.
Rob D's Gravatar
 Location: Perth, WA
 Member since 23 January 2011
 Member #: 820
 Postcount: 59

Hi Mike, bit of a coincidence here.
I'm a newbie to this forum as well and have just dug up an Astor HMQ 32vdc rural radio from my brothers property, which I'm tweaking back to life.

One caution I can offer, if the radio has valves with top cap connections, be very careful when/if removing the lead from the cap.
The goo holding the cap to the glass may have deteriorated.
If you rotate the lead connector back and forth to get it of, you may rotate the whole cap and break the wire connecting the cap to the valve's internals.

Cheers, Rob

Currently restoring Astor HMQ 32vdc
Completed and working great!!

 Return to top of page · Post #: 4 · Written at 6:32:59 AM on 23 January 2011.
Brad's avatar
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 6585

This issue generally applies to all valves with top caps though if a cap comes off not all hope is lost.

Most of the time the cap works loose due to a dry joint in the solder and this is usually caused by the constant heat the valve generates. The white muck inside the cap that looks like plaster can usually be used as a base for a tiny dab of araldite and this usually sets the cap back in place although you would first need to make sure the wire is still long enough to poke through the hole in the cap. If the wire is too short then some splicing will be necessary. If it turns out that the wire has snapped right at the glass tip then it is still possible to make a new connection but you'll need patience, steady hands and a fine-grade warding file.

Simply use the warding file to expose about 1.5mm of the wire that passes through the tip and then 'tin' the wire with some solder. This should be enough to resurrect the valve and then the splicing job, mentioned prior, can be done.

A valve a day keeps the transistor away...

 Return to top of page · Post #: 5 · Written at 10:16:58 PM on 24 January 2011.
Rob D's Gravatar
 Location: Perth, WA
 Member since 23 January 2011
 Member #: 820
 Postcount: 59

Yup, have recovered a few tc's like you mention.
Best to be proactive, if you find a loose one, unsolder it, glue it and resolder.

Another 'watchit' that comes to mind is for those dc sets that have a synchronous vibrator [no rectifier tube].
This makes them polarity conscious at the power input wires.
If you reverse connect it, you will generate -ve volts across the electrolytic filter caps and at around 150 volts, they won't put up with that for too long!

Check first by measuring with an ohm meter from the chassis frame to each power wire.
The negative side is connected to the frame and will therefore measure close to 0 ohms.
The positive side will measure about 40 ohms to the chassis.

The above measurements are at least true for my Astor HMQ

As for sets with non-synchronous vibrator and rectifier tube, I'm not sure if there is something else that makes them polarity conscious, but it's still best to check which wire is connected to the chassis and make it the negative side.
This at least will avoid any crossed power problems with other dc equipment running of the same supply.

Others may have better info on this.

Currently restoring Astor HMQ 32vdc
Completed and working great!!

 Return to top of page · Post #: 6 · Written at 12:04:27 PM on 1 February 2011.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4519

The idea is, if you can leave, or have a gap between the clip & the cap; Is to place a small screw driver between the two & carefully lever it. whilst supportiing the assembly

That way you are not twisting or placing a great deal of stress on the cap to valve bond.

The only way these would be polarity sensitive is by having electrolytics on the 32V rail.

The Majority of valve car radio's only had non polarised caps in the power supply. One Airchief I fixed could be found in a Neg earth Holden or a Positive earth Vauxhall (UK GM) with no mods, providing the voltage was right.


 Return to top of page · Post #: 7 · Written at 4:21:05 AM on 20 February 2011.
Rob D's Gravatar
 Location: Perth, WA
 Member since 23 January 2011
 Member #: 820
 Postcount: 59

QUOTE: The only way these would be polarity sensitive is by having electrolytics on the 32V rail.

Not so with synchronous vibrator which switches the secondary as well.
This acts as a mechanical full wave rectifier, eliminating the need for a rectifier tube, but makes the input volts polarity sensitive.

Currently restoring Astor HMQ 32vdc
Completed and working great!!

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