04-28-2026, 10:00 PM
Hi SRv2.
Instead of a Bonfire, you can ship them to:
11 Browning Drive
Greenlawn, 11740
and I will "fire" them
Both of these radios appear to be extremely restorable.
It appears that you have the Philco 38A which used a "combination" A/B/C battery much like the later 1.4 / 90V sets using an A/B battery. Your voltages are 3V A voltage if you have the ballast tube (that should have come with the radio because it uses the battery pack) 67V and 125V as Morzh said for B voltages, 3V C -for Output tube bias and 7.5V C- for 1st audio amp bias. The drawing is incorrect; it should be 7.5V, not 7V.
If you don't have the ballast tube, jumper the tube contacts and use a 2V power source. You can also add up the filament current, use Ohm's law and calculate the correct resistance to drop a 3V Wall Wart output to 2V.
This is an interesting set. Though released around 1934, it uses Tetrode or "Screen Grid" tubes. It may be possible that 2V RF type pentodes were not developed. The 15 has an indirectly heated cathode; it has to because it is an "autodyne" type oscillator - Mixer (1st Detector), similar to the 80 Jr and the dreaded (Sorry, Ron) 89 / 19 sets. I always thought this style cabinet was a little scary looking, but this set is an absolute "keeper"
An ARBEIII would power the set with no issue for A and B voltages. For the C voltages you could build a voltage divider but the easier thing would to obtain a 2AA Cell holder and 3 AA cell holder. (you could use AAA cells if you want. Wire these in series with the negative lead of the 2 cell holder to the positive lead of the 3 cell holder Wire the positive gf the 2 cell holder to chassis ground or the common pin. The junction of the 2 and 3 cell holders is you -3V and the black wire form the 3 cell holder is the -7.5V. These batteries will last a very long time, likely years, until internal leakage causes external leakage.
If you don't want to spend $180 on the ARBE, use the above mentioned Wall Wart and get a transformer that has a 120V input and 120V output at about 50 mA. a Bridge rectifier, 2 47uF caps and appropriate resistors will give you the 135V and 67 V on the cheap.
With either power supply, I would also put 4 1N4007 diodes in series, cathode to A-, anode to A+ to clamp any overvoltage.
I do not have this set, but I do have an RCA 5BT, using the same amplifier circuit with a 30 driver, a 19 Class B PP Output, interstage transformer and the same voltages. The amp is no slouch. I put out much more volume and better tone than the puny 0.1W to 0.24W of the later 1.4V / 90V sets.
The Zenith is really cool, as that one has the 6V / 117V power supply. That would be a bucket list set for me. Only issue is that Zenith "Black Dial" tombstones are quite collectible and expensive.
The Zenith is a very interesting setup. With the multi-contact wafer switch in battery position, the tube filaments are hooked across the 6V battery, the vibrator is on and the thing runs off 6V. In AC mode, the multi-contact rotary switch switches the filaments to the 6V center tapped secondary of the transformer, turns off the vibrator, disconnects the battery and you plug it in. Interestingly enough, the power supply appears to put out about 135VDC to the Class B Push Pull output stage. The 1J6 is essentially an octal based version of the 19.
No C battery is used on this set. The bias for the output is zero volts because a60 Amp Hour battery would run this set for an easy 100 hours, and they likely swapped the battery out with the one in their car, truck or tractor, or had a windmill charger or gas generator. The bias needed for the driver stage was generated by a cathode resistor. The secondary of the power transformer is center tapped to reduce 60 Hz hum on the filamentary cathode of the 19. Otherwise, radios of this vintage did not center tap the heater winding if all the tubes had indirectly heated cathodes.
Keep us posted, Both of these radios are absolutely restorable and will perform rather well, especially the Zenith.
BTW, yes, the power cord looks like it would fit a 7 Pin tube socket similar to the one used by a 2A7 or 6A7.
Instead of a Bonfire, you can ship them to:
11 Browning Drive
Greenlawn, 11740
and I will "fire" them
Both of these radios appear to be extremely restorable.
It appears that you have the Philco 38A which used a "combination" A/B/C battery much like the later 1.4 / 90V sets using an A/B battery. Your voltages are 3V A voltage if you have the ballast tube (that should have come with the radio because it uses the battery pack) 67V and 125V as Morzh said for B voltages, 3V C -for Output tube bias and 7.5V C- for 1st audio amp bias. The drawing is incorrect; it should be 7.5V, not 7V.
If you don't have the ballast tube, jumper the tube contacts and use a 2V power source. You can also add up the filament current, use Ohm's law and calculate the correct resistance to drop a 3V Wall Wart output to 2V.
This is an interesting set. Though released around 1934, it uses Tetrode or "Screen Grid" tubes. It may be possible that 2V RF type pentodes were not developed. The 15 has an indirectly heated cathode; it has to because it is an "autodyne" type oscillator - Mixer (1st Detector), similar to the 80 Jr and the dreaded (Sorry, Ron) 89 / 19 sets. I always thought this style cabinet was a little scary looking, but this set is an absolute "keeper"
An ARBEIII would power the set with no issue for A and B voltages. For the C voltages you could build a voltage divider but the easier thing would to obtain a 2AA Cell holder and 3 AA cell holder. (you could use AAA cells if you want. Wire these in series with the negative lead of the 2 cell holder to the positive lead of the 3 cell holder Wire the positive gf the 2 cell holder to chassis ground or the common pin. The junction of the 2 and 3 cell holders is you -3V and the black wire form the 3 cell holder is the -7.5V. These batteries will last a very long time, likely years, until internal leakage causes external leakage.
If you don't want to spend $180 on the ARBE, use the above mentioned Wall Wart and get a transformer that has a 120V input and 120V output at about 50 mA. a Bridge rectifier, 2 47uF caps and appropriate resistors will give you the 135V and 67 V on the cheap.
With either power supply, I would also put 4 1N4007 diodes in series, cathode to A-, anode to A+ to clamp any overvoltage.
I do not have this set, but I do have an RCA 5BT, using the same amplifier circuit with a 30 driver, a 19 Class B PP Output, interstage transformer and the same voltages. The amp is no slouch. I put out much more volume and better tone than the puny 0.1W to 0.24W of the later 1.4V / 90V sets.
The Zenith is really cool, as that one has the 6V / 117V power supply. That would be a bucket list set for me. Only issue is that Zenith "Black Dial" tombstones are quite collectible and expensive.
The Zenith is a very interesting setup. With the multi-contact wafer switch in battery position, the tube filaments are hooked across the 6V battery, the vibrator is on and the thing runs off 6V. In AC mode, the multi-contact rotary switch switches the filaments to the 6V center tapped secondary of the transformer, turns off the vibrator, disconnects the battery and you plug it in. Interestingly enough, the power supply appears to put out about 135VDC to the Class B Push Pull output stage. The 1J6 is essentially an octal based version of the 19.
No C battery is used on this set. The bias for the output is zero volts because a60 Amp Hour battery would run this set for an easy 100 hours, and they likely swapped the battery out with the one in their car, truck or tractor, or had a windmill charger or gas generator. The bias needed for the driver stage was generated by a cathode resistor. The secondary of the power transformer is center tapped to reduce 60 Hz hum on the filamentary cathode of the 19. Otherwise, radios of this vintage did not center tap the heater winding if all the tubes had indirectly heated cathodes.
Keep us posted, Both of these radios are absolutely restorable and will perform rather well, especially the Zenith.
BTW, yes, the power cord looks like it would fit a 7 Pin tube socket similar to the one used by a 2A7 or 6A7.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
"Let us begin to do good"- St. Francis
Best Regards,
MrFixr55
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