[Bob Andersen]

Time to come clean - I'm the guy that bought the 623 discussed in this thread.
I'm a sucker for tombstones and I like a challenge

It arrived a few days ago and I finally had time yesterday to fully examine it. Somehow, the cabinet has lost virtually all of it's finish but it still has a decal.
There's also a bit of separation and some dings. Otherwise, it's in very good condition. Every knob, screw, tube, etc is there. Even the rubber mounts are still very pliable.
[Image: http://farm9.staticflickr.com/8464/81206...08d9_z.jpg]

[Image: http://farm9.staticflickr.com/8463/81206...f049_z.jpg]

The dial scale is in good condition.
[Image: http://farm9.staticflickr.com/8195/81206...b9aa_z.jpg]

A little dirty but minimal corrosion.
[Image: http://farm9.staticflickr.com/8191/81206...ec5b_z.jpg]

It doesn't look to me like it was ever serviced. I don't see a single replaced component.
[Image: http://farm9.staticflickr.com/8468/81206...cd62_b.jpg]


The speaker is also very nice I hooked it up to a function generator and the low frequency response stinks but otherwise it sounds fine.
[Image: http://farm9.staticflickr.com/8475/81206...717f_z.jpg]

Here it is dwarfed by it's 643 big brother. Yes, I'll get around to finishing the 643 soon. Lately, I've been focusing on refinishing as much as possible before winter sets in.
[Image: http://farm9.staticflickr.com/8189/81206...dcc5_z.jpg]


One thing I'm puzzled about is the tube lineup. All the service info I can find shows a type 34 tube while this tube chart has a type 1A4.
That makes me think this is an early version perhaps ?
[Image: http://farm9.staticflickr.com/8467/81222...48a5_z.jpg]

[Steve Davis]

Well, I'm happy to hear the radio found a good home.

Steve

[jerryhawthorne]

Looks like a great project and solid. I think it's "big brother" will be very happy setting next to it. Keep posting you progress, we all learn.
Jerry

[Arran]

It has been my experience with the farm battery radios that I have owned that the vast majority of them have never been serviced and still have all of the original capacitors and resistors in place. When you think about it other then age the components are never really put under any great stress, the tube filaments run more or less cold since they are low voltage and low current, the B+ voltage typically ranges between 45 and 135 volts, mostly around 90 volts.
They were also never played day in and day out like an AC set, if they didn't want to continuously buy new batteries they had to ration their listening time, though many used a storage battery and rheostat for the "A" supply to get around this. Also because of the rural electrification programs after the war many of these sets were retired for AC operated replacements. Believe it or not in many cases you can hook up the correct voltages to one of these sets and it will play, although some have an electrolytic or two that will be dried out and need immediate replacement.
Regards
Arran

[TA Forbes]

Agree about the battery sets. My experience is that you often find them in very good shape.

The 1A4 replaced the 34 tube, so it is probably a later run. Both of mine are 34 tube variants.

The 623 has an interesting output system that uses a 19 dual triode tube.

[jerryhawthorne]

If your radio uses 90V and 1.5, there are some very nice schematics for building your own power supply using A/C power. Built a couple for my farm radios and they really work well. No batteries to change out. Cost for parts really cheap. You will spend more for the aluminium box and the perf board. Can turn out looking exactly like an original battery with the graphics applied.
Good luck, nice looking radio.
Jerry

[Image: http://i303.photobucket.com/albums/nn129...Radio2.jpg]

[Chuck Schwark]

According to the Production Change Notices for the 623, Run 4 (Oct. 1, 1935) had the 34 tube changed to the 1A4 and the 1st. IF transformer changed to increase sensitivity.
You your set is a later run version. Production went through 9 Run changes (component changes, additions, removal, etc.) during its production lifetime.

Service Bulletin No. 225 shows the 34 tube used initially.

Chuck

[Chuck Schwark]

Also, I took a look back through the pictures and it looks like a "computer-grade" electrolytic bolted to the rear chassis wall?

Maybe someone has been in there in the past?

Chuck

[Bob Andersen]

Thanks for all the great info guys Greater sensitivity sounds like a good thing to me
I like that 19 output stage too - push-pull in one tube. I really hope the output transformer is good unlike my 643.

Both this set and the 643 use 135, 67.5, 2, -3 and -7.5 volts.
I've already been noodling around with some designs using the LR8N3 HV regulator as shown in this article by Leigh Bassett.

[Bob Andersen]

Also, I took a look back through the pictures and it looks like a "computer-grade" electrolytic bolted to the rear chassis wall?

Maybe someone has been in there in the past?

LOL No, it really is the original

[Image: http://farm9.staticflickr.com/8467/81238...5ce4eb.jpg] [Image: http://farm9.staticflickr.com/8190/81238...96f85b.jpg]

[Chuck Schwark]

OK, I see it is, indeed, an original Philco part and the Philco service bulletin for the 623 parts listing confirms that part number. I guess the photo angle made the top terminal area hard to distiguish and without any can markings showing, it fooled me.


Chuck

[Bob Andersen]

Oh it fooled me at first too until I unmounted it and saw Philco printed on it

[Arran]

That cap looks like the four section one under the chassis of my Canadian Philco 3118, which is also mounted in a similar fashion, it was a 1935 model I think. I'm not sure when they came out with that style of cap, maybe 1933 or so, but I have a 48-482 with a very similar style of cap underneath, obviously it was a fairly successful design.
Regards
Arran