30-06-2020, 02:35 PM
(This post was last modified: 30-06-2020, 02:47 PM by Mike Watterson.)
I've not found yet the Russian circuit for the 1j37b or 1i42a
Here is the 1j42 construction, which uses much closer spacing than the other Rod Tubes and it's the only one known with the triangular anodes:
https://www.radiomuseum.org/forum/142_ph...ves.html#1
This explains why the 1j37b was used for AGC
https://www.radiomuseum.org/forum/russia...bes.html#4
"As illustrated in the earlier posts, the control grid rods, when driven together as one control grid, give a very pure square law control of Anode current by control grid voltage.
When one of the control grid rods is biased at a fixed DC voltage, the other rod can be used for transconductance control over a spectacular range exceeding 7 decades!
A DC sweep of this control rod from 0V to -20V, will change the Anode current from 1mA to 100pA in a very smooth logarithmic progression. The screen voltage for this sweep was 30V and the plate voltage was wired together with the suppressor grid in a tetrode configuration and biased at 10V."
Further down the page
![[Image: 1zh38b_Mixer_at_half_LO.GIF]](https://www.radiomuseum.org/forumdata/users/4942/Russian_Subminiature_Tubes/1zh38b_Mixer_at_half_LO.GIF)
However normally the RF in would be LO1 and LO2 pins and the Local Oscillator would be on RFIN pin, as this gives rejection to out of IF band RF or IF band at the RF input.
Normally g3 goes to 0V. This is example is suggested by the idea of the LO being 19KHz pilot and the "RF IN" being the 38kHz L-R DSBSC multiplex.
Here is the 1j42 construction, which uses much closer spacing than the other Rod Tubes and it's the only one known with the triangular anodes:
https://www.radiomuseum.org/forum/142_ph...ves.html#1
This explains why the 1j37b was used for AGC
https://www.radiomuseum.org/forum/russia...bes.html#4
"As illustrated in the earlier posts, the control grid rods, when driven together as one control grid, give a very pure square law control of Anode current by control grid voltage.
When one of the control grid rods is biased at a fixed DC voltage, the other rod can be used for transconductance control over a spectacular range exceeding 7 decades!
A DC sweep of this control rod from 0V to -20V, will change the Anode current from 1mA to 100pA in a very smooth logarithmic progression. The screen voltage for this sweep was 30V and the plate voltage was wired together with the suppressor grid in a tetrode configuration and biased at 10V."
Further down the page
However normally the RF in would be LO1 and LO2 pins and the Local Oscillator would be on RFIN pin, as this gives rejection to out of IF band RF or IF band at the RF input.
Normally g3 goes to 0V. This is example is suggested by the idea of the LO being 19KHz pilot and the "RF IN" being the 38kHz L-R DSBSC multiplex.
