Info on Hyde Park Radio
 

Looking for information on a 1930's Hyde park radio made by the Low Supply Co. I bought this about 30-35 years ago and thought I'd re-cap it. All tubes light as well as the original dial lights but it just hums, loudly. one tube is loose in it's base. I have no setting info for at least 2 of the tubes for my tube tester.
Any help would be appreciated.

It looks like a lot of electrolytic capacitors in it. Please reply with a tube line up and someone will recognize it. :yes:

That's likely all it needs, a recap of the wax caps and the electrolytic caps. Tubes are likely okay, even the one with the loose base likely works. Tubes will last forever if never used, on the shelf or in a radio that sat unused for years. Not so for caps, the wax caps absorb moisture from the air and become electronically leaky, and the electrolytic drys out. Replace each cap one at a time, so you don't forget where it connects to. I don't try to remove all the old cap's leads from tube socket or other terminals (these can be fragile), just snip the lead, maybe leaving enough to make a "J" hook to connect the new cap to. Do place physically the cap and the leads approx where the old cap was. And be sure the new leads can't short to something, and reuse any insulating tubing the old cap had.

Looks like one of those old 'lytics puked its little guts out in there. +1 what dieseljeep wrote: give us the tube numbers and we can get close to a schematic. Many early to mid thirties TRF sets were made on a similar pattern.

Those small TRF's are kind of neat to work on, once in a while. :thmbsp:
It looks to me that, the tube on the rear right of the chassis is a glass ballast tube. That could be the tube with the loose base.
The other tubes would be a 6D6, 6C6, 43 and a 25Z5. It also looks like it has a choke as well as a field coil.
I like that kind of dial too. :yes:

That's what one of the semi readable schematics pasted on the case bottom re: tube layout. But there are 2 tube line ups. Mine has the ballast tube in the 5 tube line up. 2 of my tubes are unreadable the others are 43,25Z5 and 185r8 which is not listed on the line up. And it does have a choke plus the field coil.

The 185r8 is the ballast tube. In the original picture, the tube right behind the speaker, should be the 6C6, where the shielded tube is a 6D6.
Don't worry about the tubes for now. Recap the radio and then check the performance. :thumbsdn:

Thanks, that is my plan. I'm listing the caps as I type for ordering. I'm not changing the mica caps, just the electrolytics and I'm using a higher voltage than the original (eg 650V for the 400V and 50V for the 25V).

Nothing to gain from using higher voltage; in fact that could cause long term difficulty.

Also replace any paper capacitors, particularly the audio coupling.

That radio has 400v electrolytics? Those are probably the only caps, the original servicer had on hand. 160 volt caps for the power supply and 50 volt units for the cathode bypass. All the coupling caps can be 630 volt caps.
The radio has only a 120 volt B+ supply.

Paper caps will be replaced also. I think there are a couple of wax coated paper caps in there. My understanding on higher voltage caps is that they are easier on tubes allowing them to potentially last longer. I'm not aware of any long term detriment.

I always use caps that exceed the original voltage specs. What long term difficulties would this cause ?

It has three .01uF 400V and one .01uF 600V electrolytic caps.

630 volt caps are the standard that most people nowadays use to replace all wax paper caps originally rated at lower voltages. As to electrolytics, at one time higher voltage rated caps might not have formed well at lower voltages but I understand this is no longer true. Even so, I use 160 volt electrolytics on AC/DC sets which beats the old 150 volt rating.

When you use an electrolytic capacitor at reduced voltage, sometimes it gradually reforms and the capacitance and leakage increase. It takes a long time and probably isn't an important issue. And perhaps today's components don't suffer from that.

Paper capacitors don't have a problem. However, the increased cost and size of higher voltage don't make reliability better. In fact, larger capacitors tend to have poorer high frequency performance; i.e., lower self resonant frequency.