[dconant]

Hello, I sure hope there is someone out there that knows this radio. I am just getting started on scoping out the schematic. 

I am likely to have many questions on this radio since there has been a lot of hacking and slashing going on in there. Some mods to the wiring as well. 

The tubes are 2.5 filaments except for the 80 tube. The 2.5 filaments are all tied back to the power transformer which has terminals instead of wires coming out of it. Can I wire these from tube to tube and therefore have just one wire going to each terminal of the 2.5 terminals? Would this likely to be because of current?

[morzh]

This radio, I think, from the memory, is TRF similar to Philco 20. Same tubes and all.

Yes this could be their attempt to equalize the filaments, but I think tube-to-tube would be just fine, with the wire gauge being appropriate (if there are 3 of them, the first section would conduct over 5A per wire).
I think using AWG18-20 is just fine.

[radiorich]

Hello mike,
My Gloritone is funny the chassis is upside down !

Sincerely Richard

[Arran]

I have a Canadian version of one of these, it was made under license from U.S Radio & TV by Grimes-Phonola. The construction is very similar but Grimes-Phonola designed and built their own cabinet, and placed an escutcheon labeled "Dictator" around the dial rather then Gloritone. Dictator was the private label brand for Hudson's Bay Company radios during the 1930s and 40s, post war they adopted the "Baycrest" brand since it didn't have the negative connotation with autocratic European politicians like the Austrian Painter, or the Duce.
Anyhow it is basically a screen grid TRF circuit that they used, similar to a Philco 20, but with a single ended #45 output rather then push pull 71As, and the model 20 has an extra TRF amplifier stage. In any event I would follow the diagram with the heater wiring, it's a fairly basic radio if all of the coils and transformers test out all right. http://www.nostalgiaair.org/PagesByModel...040710.pdf With mine I think I will replace the electrolytics with motor run caps, there is a big clamp that held the original filter caps in place, which I think were so called "dry" electrolytics, which are long gone.
Regards
Arran

[dconant]

I have got petty far along on the radio so far. My chassis is upside down as Richard says. The caps in big clamp are long gone with a dual 4 wire electrolytic in its place. I am finding some original parts (caps) are missing as well. Several wires not soldered.

I see there is a early and later version of the schematic. I can't quite figure out which one I have. Looks like maybe someone was trying to make a late version out of the early or the other way around. Best I can tell between the two is the volume control. The volume control in my radio is not original as it says Philco on it with the shaft modified. Since the Philco is 2K I would guess maybe it is wired as early version. The B- is wired directly to one of the out pins of the volume control which looks wrong to me. I'm thinking wiring as the late version.

Transformer is good (whew) as well as FC and OT.

Antenna coil has a bad winding but not sure which one it is yet. Bummer. I suspect some miss-wiring maybe burned out the one inside the coil tube. Have not got to the other two coils yet. Lets hope they are good.

The three section candohm is totally shot as well as one other single candohm. Found a 2 watt resistor in a plastic sleeve that should be 50K and it measures close to that but its painted white. Beats me why. Lots of extra long wires in here.

Since several neat parts are gone from this radio I plan to just use terminal strips with modern parts.

Arran why would you use motor run caps? I was planning on using 10MF ECaps.

[Arran]

I was planning on using motor run caps because the original electrolytic cans, which I believe were in cans, are missing, and motor run caps, if you have the space, are a more permanent replacement anyhow. I was comparing the two schematics, actually three, the one for my Grimes-Phonola made "Dictator", and the two U.S Radio and TV ones, are all called a model 27 by the way, and I couldn't really see the differences other then they substituted a .6 uf cap in place of a .5 uf cap as one of the bypass capacitors in the later version. Maybe they thought there might be an oscillation problem, or maybe they got a deal on some .6 uf capacitors? The originals would have been in side of some metal boxes filled with tar, but I can't say whether they had a terminal strip or just had a bundle of wires coming out of them, it's been five years since I had the chassis out to look at it.
I didn't notice the change in the volume control circuitry until you pointed it out, on the early version, which is the same as mine, the volume control is in the cathode circuit of the RF amplifier tubes, presumably to change the tube bias, in the later version the control is in the antenna circuit. I'm not sure why they changed it, maybe a cost cutting exercise since a wire wound rheostat would have cost more, where they could get away with using a carbon pot in the antenna circuit.
Regards
Arran

[morzh]

Motor caps are yooge.
Of course, used with things otehr than motors, they are also almost eternal.

[David]

Motor run caps are also used in portable brush less generators.

[Arran]

Also since motor run caps are non polarized, and typically AC rated, you don't have to worry about ripple, or ESR with them, they also do not dry out, and many have a fuse built in. I have one that came with a metal halide ballast, it's 24 uf at 480 volts, 50 or 60 cps, it's too large for the model 27, but a pair of 10 uf ones would probably work just fine, many come in nice metal cans similar to the old wet electrolytics of the 1920s and 30s. The main issue is that you want to get them from a reputable source, like Mouser, or DigiKey, and not Alliexpress or Amazon.
Regards
Arran

[radiorich]

Hello dconant.
You can also use film capacitors !!
Maybe someone was working off of two schematics.
It sounds like you need to really check everything over to make sure everything is correct .

Sincerely Richard

[MrFixr55]

Hi dconant.

I have not worked on the 27 but have worked on the somewhat similar Gloritone 26 for a friend.  These are TRF sets with 2 stages of RF amplification, using 24A tetrodes, and a "biased" detector.   This is the same as the Philco 20 and Gloritone 26 except that the Philco 20 and Gloritone 26 use a 24A as the biased detector while the 27 uses a 27 triode.  The 20 uses an extra stage of audio amplification and a push-pull output.

Yes, the Gloritone 27s have an upside down chassis.

The wiring of the volume control may look weird to those working on later model radios (Why is the wiper grounded?) but analyzing the circuit makes sense.    In the early Non-AVC TRF sets, volume was controlled by one of several techniques:

• Shunting the antenna input. (This was done on the early TRF RCA Radiolas.)
  
• Varying cathode bias on the RF and / or IF amplifiers. (This was done on the early Gloritone 27, RCA Radiola 60 and 80, the R7 and other early RCA sets.)
  
• Doing both with ganged control elements.  (This was done in the Philco 20.)
  
• Controlling screen voltages on tetrode RF Amps.
  

The control on the late Gloritone 27 and the Gloritone 26 does both, adding cathode bias and shunting the antenna input, using only one control with only one element.  As the control is turned towards minimum volume, the antenna terminal is shunted by low resistance and cathode bias of the 2 RF amp stages is increased, lowering the gain of the RF Amps.  As the volume control is turned to increase volume, bias is lowered, increasing RF Amp gain and the shunt resistance is increased to a level much higher than the resistance of the antenna coil.  This is why the center tap is grounded.

It is always best to attempt to rewire a radio in the same manner as originally wired.  However, for this radio, going from socket to socket for the filament windings is OK to do.  Yes, all filaments except the rectifier are powered by the same 2.5VAC secondary.  The center tap of this secondary is grounded.  Use sufficiently heavy wire, as total filament load is approximately 6.5A.  Use a minimum of 18 gauge solid or 16 gauge stranded wire, as a twisted pair.  I would start at the '45 output tube but follow the original routing.

I have not used motor caps but those suggesting them are experts who have used them successfully.

Hope this all helps.

[dconant]

It sure looks to me like someone was working off two schematics. I have been checking every part and wire with both schematics. Since the volume control is not original to the radio, a Philco 33-5040 part, I'm not sure which way to wire the radio. The Philco pot is a 2K pot that does not match either value of the schematics. So if I wire the late version do I need to have a wire wound pot? If I wire the early version do I need an 8K pot?

I did find a You Tube video by buzz1151 on the same radio. His wiring is much neater than mine. I believe his radio is the late version. His pot and power switch looks exactly like the one in my Philco 91.

Thank you MrFix55 for the details on how the volume control works.

[radiorich]

Hello guys,
Well i just looked at my Gloritone and low and behold it is a model 27 !!
Yes, Mr Fixr55 I have couple Sears radios that also have the Volume set up very similar .
Well buzz restored a 27 about 8 months ago here is the video
gloritone 27
Sincerely Richard

[morzh]

Yep. It is a light version of Philco 20.
I guess it was soon after the 24 tube appeared on the market and everyone started using it.
Other than one less 24 tube and the 45 SE vs 2x71A P-P output.

There is a little bit of difference in using the tubes: 20 has the 3rd 24A as the tuned amp-detector (plate detector) and the 27 is the interstage driver; in Gloritone both 24 are RF stages and the 27 is both the detector and the interstage driver.

[MrFixr55]

Does the Philco pot have only 1 element (2 or 3 terminals) or is it ganged (5 or 6 terminals)?

You state that one connection is to B-. Is it to chassis ground? is it one end or is it the wiper?

The early 27 uses a 1KOhm pot and controls only the cathode bias of the 2 24s. the wiper goes to the cathode and the entire resistor is in series with the speaker filed coil across B+
The late 27 and the 26 use an 8K pot whose center tap is grounded. one leg is tied to the cathodes of the two 24s; the other leg is tied to the antenna connection.

The Philco 91 uses a pot in the audio input like most radios of the later 30s to the end of the tube era.

As to what wattage pot is needed, my rough guess is that the pot must dissipate 5W at minimum volume. This is assuming that at minimum volume, the voltage across the pot is 50V. I may be totally wrong on this; the voltage may be much less. However, the maximum plate and screen current at 180V for this tube is approximately 5 mA. for 2, this is 10 mA. At 50V, 50V X10mA = 5W. So I would use a pot with a minimum of 5W dissipation. A 10K pot would work. I don't know if you can find one of these with 5W dissipation; that value is rather high for a 10K pot. I don't have a Gloritone. The one I fixed was for a friend who sold it. Maybe one of the members who has a working one can measure cathode bias voltage to ground at minimum volume. My guess is that whatever wattage, a linear taper pot can be used. If the pot is a 2K pot, it should be wired per the early schematic. If the Pot is 5K or higher, the later scheme can be used.

In any case, when using this or any radio where the volume is controlled by varying cathode bias, start with the volume control at minimum. Since there is no AVC, a high volume setting will cause the RF stages will saturate with a strong station, causing no sound. this is not a defect; this is how the radio operates.

BTW, the cathode bias resistor for the detector is marked 50 M. This is not megohms; the "M" indicated kilohms.