parts list

 

The parts listed under "cathode bias" are to be soldered to the VTX power tube board.  Everything else mounts within the extension chassis.  Most components mount on two circuit boards, as seen in my drawings; a few components mount directly to the back of pots.

The stars next to some component values are my non-specific indication that these components should be "up-rated".

For capacitors, the voltage rating should be higher than the +HV rail of the circuit in question.  In this amp, with its relatively high +525V rail, the starred capacitors should have voltage ratings of 630V or higher.  Unmarked capacitors should generally be rated at 50V.

For resistors, the star means that the wattage rating should be higher.  Unless marked otherwise, in this amp, I am using 2W for starred resistors.  Unmarked resistors are 1/4W.  The up-rated resistors should be mounted a few mm above the board, and similarly separated from any other components, for proper heat dissipation.

The '+' sign on capacitor values of course indicates that these are polarized electrolytics.


Comments

Post a Comment

Popular posts from this blog

final interconnection, first power test

Image
Connecting the new circuitry to the VTX chassis.  Most connections are through the 12-position "Euro" terminal strip, except heater power (to the left) which is hard-wired. First power-up, with no tubes inserted.  LEDs ahoy!  This just verifies that the +15V power supply is working, and I haven't made any grievious errors in the wiring. I verified that the channel-select 3-way switch works, turning on and off the yellow and green LEDs on the VTX, and the preamp-select 3-way works, turning on and off the white LEDs (yes, those are white, not blue as they appear in the camera). And I verified that the HV supply works, by taking it out of standby and observing that the blue LED of the RGB pilot light illuminates.  (It's a bit dim with the 10M resistor though, I guess I need to decrease the resistance; gotta take care with the power dissipation...)
Read more

schematics of my mods

Image
  Again, caveats from the previous post apply here as well.  Most significantly, I have not yet built the boost circuit, nor even verified whether the VTX power transformer can handle the additional heater current load.  And some of the wiring of the phase inverter, vis a vis nfb, has not yet been implemented or tested.  So these circuits are to some extent, aspirational.
Read more