06-22-2011, 06:54 AM
It appears that both the 37-116 and 38-116 use 11 tube shields. The 37-116 service info does not show a shield over the 6J5 1st audio tube, but I think it does have one. I no longer own any 37-116 or 38-116 models so can't check for myself.
Now as to the tube complement. Short answer is no - the 1938 tube lineup would not be used, nor would they work properly, in the 37-116 without some modifications.
Discriminator - 6H6G dual diode in the 37-116, 6J5G triode connected as a diode in the 38-116 with two 6J5 tubes being used instead of a single 6H6G.
AVC - Both use 6J5G tubes, but in different positions (compare the service information).
1st Audio - 6J5G in the 37-116, 6R7G in the 38-116. The 6R7G is a dual diode-triode, with a grid cap. The 6J5 has no grid cap. A 6J5 could be used in place of a 6R7G with some modification.
Now as for the RF unit: As mentioned previously, the 38-116 Code 121 uses the 1937 RF unit, with the same tube lineup (6N7G, 6A8G, 6L7G, 6K7G). 38-116 Code 125 uses a different RF unit with the following tubes: 6N7G, 6A8G, 6A8G, 6U7G.
6K7G is a substitute for 6U7G.
But 6L7G and 6A8G do not substitute for one another as they are configured differently.
Finally, let's mention the audio output tubes. Most 37-116 models use 6B4G triodes; 38-116 models use 6L6G pentodes.
Most 37-116 models are Code 122 (with automatic tuning, 6B4G output tubes). Some are Code 121 (conventional 1937 round dial, no automatic tuning, 6B4G outputs). But there are also Codes 125 and 126 that use 6A5G triode output tubes. No schematic that I am aware of exists for these two variants, although these codes are mentioned in the 1946 Philco Quick Selector Parts Directory.
Confused enough already?
Now as to the tube complement. Short answer is no - the 1938 tube lineup would not be used, nor would they work properly, in the 37-116 without some modifications.
Discriminator - 6H6G dual diode in the 37-116, 6J5G triode connected as a diode in the 38-116 with two 6J5 tubes being used instead of a single 6H6G.
AVC - Both use 6J5G tubes, but in different positions (compare the service information).
1st Audio - 6J5G in the 37-116, 6R7G in the 38-116. The 6R7G is a dual diode-triode, with a grid cap. The 6J5 has no grid cap. A 6J5 could be used in place of a 6R7G with some modification.
Now as for the RF unit: As mentioned previously, the 38-116 Code 121 uses the 1937 RF unit, with the same tube lineup (6N7G, 6A8G, 6L7G, 6K7G). 38-116 Code 125 uses a different RF unit with the following tubes: 6N7G, 6A8G, 6A8G, 6U7G.
6K7G is a substitute for 6U7G.
But 6L7G and 6A8G do not substitute for one another as they are configured differently.
Finally, let's mention the audio output tubes. Most 37-116 models use 6B4G triodes; 38-116 models use 6L6G pentodes.
Most 37-116 models are Code 122 (with automatic tuning, 6B4G output tubes). Some are Code 121 (conventional 1937 round dial, no automatic tuning, 6B4G outputs). But there are also Codes 125 and 126 that use 6A5G triode output tubes. No schematic that I am aware of exists for these two variants, although these codes are mentioned in the 1946 Philco Quick Selector Parts Directory.
Confused enough already?
--
Ron Ramirez
Ferdinand IN
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