05-14-2019, 03:12 PM
The Plate detector is known to distort, especially at low signal level (it is quite OK at larger levels). Not just Philco, everyone used it and it is a known problem.
The Plus of that: only one triode tube is used to both detect and amplify, no need for diode and then a triode, even if in one tube (at the time those dual diode-triode tubes might not even exist).
The minus is obvious.
The remedies are few:
- remove the large value feedback cap in the Cathode and replace it with a small (under 1000 pF) one. This noticeably improves the sound quality but sacrifices the gain, so the sensitivity drops.
- simply remove the existing tube, change the socket (if needed) and use a tube like the 75 to detect and amplify the signal. This will remove the problem altogether, but the authenticity of the radio will be violated.
- someone might think of something else.
The Plus of that: only one triode tube is used to both detect and amplify, no need for diode and then a triode, even if in one tube (at the time those dual diode-triode tubes might not even exist).
The minus is obvious.
The remedies are few:
- remove the large value feedback cap in the Cathode and replace it with a small (under 1000 pF) one. This noticeably improves the sound quality but sacrifices the gain, so the sensitivity drops.
- simply remove the existing tube, change the socket (if needed) and use a tube like the 75 to detect and amplify the signal. This will remove the problem altogether, but the authenticity of the radio will be violated.
- someone might think of something else.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
