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 Mystery Philco Radio
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 Return to top of page · Post #: 1 · Written at 6:16:21 PM on 25 September 2021.
Scotty's Gravatar
 Location: Melbourne, VIC
 Member since 26 December 2010
 Member #: 794
 Postcount: 328

Hi all,
I’ve had this Philco radio for a few years, I can identify it’s model. It’s working but has a hum (like a faulty electrolytic cap) it looks to have been modified as it has a solid state rectifier fitted in a separate power supply chassis at the bottom of the cabinet.
Hopefully someone here can identify the model and year. From there hopefully we can work out why it hums.

Philco Console Radio
Philco Console Radio
Philco Console Radio
Philco Console Radio


 
 Return to top of page · Post #: 2 · Written at 11:40:58 PM on 25 September 2021.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 6625

Photos uploaded.


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A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 3 · Written at 11:48:00 PM on 25 September 2021.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6238

... meanwhile, what's the valve line-up?


 
 Return to top of page · Post #: 4 · Written at 2:38:09 AM on 26 September 2021.
Robbbert's avatar
 Location: Hill Top, NSW
 Member since 18 September 2015
 Member #: 1801
 Postcount: 1522

If there's a solid-state rectifier, what's that valve rectifier doing there? Just for looks?

No power transformer mounted on the chassis, I suppose it's in the metal box.

Strangely, it looks like there's 2 different-sized output valves, as silly as it sounds.

The list of valves being used could be interesting...


 
 Return to top of page · Post #: 5 · Written at 7:22:49 AM on 26 September 2021.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 6625

The two output valves are probably just different brands.

It's a guess but I think AWA had something to do with the make up of that receiver, at least with the innards. The colour of the chassis and the stencilling seems familiar.

Someone has done an 'upgrade' at some stage. The power cord has the familiar 1970's Burton moulded plug top. Check under the chassis to see if the cathodes have been disconnected from the rectifier valve socket.

Looking closely, the valve socket for the rectifier has either been replaced at some stage or added later on by a tinkerer. I can't find any material on a "Model 321" in the usual places and most Philco material related to American models.


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A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 6 · Written at 9:12:26 AM on 26 September 2021.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 2018

Looks like a battery set that's been heavily modified. Many were.


 
 Return to top of page · Post #: 7 · Written at 9:42:02 AM on 26 September 2021.
Scotty's Gravatar
 Location: Melbourne, VIC
 Member since 26 December 2010
 Member #: 794
 Postcount: 328

I’ll post the valve lineup today.
The rectifier valve appears to for appearance only. Only the heaters are wired on it.
The metal box in the bottom of the cabinet has 3 transformers fitted, the solid state bridge rectifier and a strange array of 4 electrolytic capacitors, 3 x 220μF and 1 x 47μF cap. All are rated at 63V which seems very low voltages given most are usually 400v plus.
I have no idea what changes have been made in the main chassis.
It takes about 30 seconds before any audio is heard. When it eventually comes on, the hum is loud and the radio puts out a fairly low volume overall.


 
 Return to top of page · Post #: 8 · Written at 1:48:26 PM on 26 September 2021.
Scotty's Gravatar
 Location: Melbourne, VIC
 Member since 26 December 2010
 Member #: 794
 Postcount: 328

Valve lineup is difficult as majority no longer have their labels on them.
There are 7 valves: only 2 I could read are 6U7 and 6J8. There is a 19 stamped on the chassis under one of them and 30 under the other.
Not much help I’m afraid


 
 Return to top of page · Post #: 9 · Written at 2:28:01 PM on 26 September 2021.
Robbbert's avatar
 Location: Hill Top, NSW
 Member since 18 September 2015
 Member #: 1801
 Postcount: 1522

Are the valves all octal types?

If so we could take a stab at the lineup, for example 6J8G, 6U7G, 6B6G, 6V6G, 6V6G, 5Y3G. Unfortunately I can only see 6 valves in the photo. Perhaps there's another 6U7G hiding out of sight.


 
 Return to top of page · Post #: 10 · Written at 2:41:49 PM on 26 September 2021.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4545

We can speculate that with what is likely 5Y3 / #80 LH on the rear view that's the rectifier & looks like one. 6J8 is late 30's and superseded other Pentagrids where there was SW. It will be the mixer / oscillator. 6U7 is a cranky RF Pentode when unshielded and can be a pre-amp ahead of 6J8 and the first IF after it.

So it then comes down to sockets. If they remain Octal, then its liable to be something like a duo diode pentode, or duo diode triode 6B6, 6B8 and then two 6F6's in push pull.

3 Gangs says it has a preceding RF stage. If it has no SW 6J8 may have been 6A8.

Marc


 
 Return to top of page · Post #: 11 · Written at 2:45:46 PM on 26 September 2021.
Redxm's avatar
 Location: Tamworth, NSW
 Member since 6 April 2012
 Member #: 1126
 Postcount: 448

That output transformer isnt original. There is a Philco group on facebook. Mainly US collectors but someone locally might recognise it. Maybe start tracing the circuit if you can.

Could be a NZ produced set as well.

The 19 & 30 stamped on the chassis may indicate a battery set that was converted. Quite possible as it looks to have an RF stage


 
 Return to top of page · Post #: 12 · Written at 3:03:00 PM on 26 September 2021.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6238

Valve lineup is difficult as majority no longer have their labels on them.

A few things to try:

* Under good strong light, breathe on the glass where the printing should be.

* Put the valves in a freezer for a while and when they emerge into room temperature air the printing can sometimes become apparent

* Use black light (i.e. safe UV).


 
 Return to top of page · Post #: 13 · Written at 5:00:43 PM on 26 September 2021.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 6625

Could be a NZ produced set as well.

Good point, as there is a slight American flavour to the style of the cabinet. The photos are low resolution so I cannot read the text on the ARTS&P label. If it says Dominion of New Zealand instead of Commonwealth of Australia then the chassis was made across the ditch. The year letter is D which means 1937.

The capacitor ratings are very odd. I'd assimilate 63VW with a battery set that has been modified to run on the mains. But the chassis is fitted with a 6U7 and 6J8 which were mains valves.

Perhaps there's another 6U7G hiding out of sight.

There are two valves next to the tuning gang. Smile

As GTC said, we need to know the whole valve line-up and out of curiosity, a gander at the tuning dial (behind the faded plastic cover) would be handy too, even if only to confirm country of origin.


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A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 14 · Written at 7:00:43 PM on 26 September 2021.
BringBackTheValve's Gravatar
 Location: Linton, VIC
 Member since 30 December 2016
 Member #: 2028
 Postcount: 274

Three transformers!!!

Good chance one may be a choke (look up Pi filters)

This could explain the strange electro cap arrangement, and also your excess hum if cap values were not considered.


 
 Return to top of page · Post #: 15 · Written at 8:53:11 PM on 26 September 2021.
Robbbert's avatar
 Location: Hill Top, NSW
 Member since 18 September 2015
 Member #: 1801
 Postcount: 1522

There are two valves next to the tuning gang.

Hey, you're right. I had to look a few times before I could be sure.


Definitely the dial cover needs removing, looks like 4 wood screws holding it on, so we can see what's hiding beneath.

The power supply with its 63 volt capacitors seems inexplicable at the moment. Definitely need more details, and voltage measurements.


 
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