Firstly, thanks all for the very positive responses I've received so far. I redid the neutralizing circuit and instead of a hard wired feed off the anode through a blocking cap to the neutralizing ca
Hi Roger, First, is the circuit push pull/parallel or are all tubes in parallel? If they are push pull you will need two neutralizing capacitors (cross neutralization) If all are in parallel the lead
-- ORIGINAL MESSAGE --(may be snipped) REPLY: A well designed amplifier should be stable without the above loads. Not all amps are but it is a good target to shoot for. 73, Bill W6WRT _______________
I am trying to find out what you are trying to do. "I redid the neutralizing circuit and instead of a hard wired feed off the anode through a blocking cap to the neutralizing cap, I setup a single ad
Sounds like you are adding POSITIVE feedback, not negative! Look up 'bridge neutralization' in an ARRL or Bill Orr handbook. The grid side of the neutralizing capacitor goes to the bottom of the grid
I am trying to find out what you are trying to do. "I redid the neutralizing circuit and instead of a hard wired feed off the anode through a blocking cap to the neutralizing cap, I setup a single ad
I am trying to find out what you are trying to do. Me Too Ron, He has to make the amp DC stable before hooking up the input and output RF networks. We don't know if that's the case yet. Don W4DNR __
Sorry, I thought it was clear what I was trying to do. I have four 4x150a tetrodes in parallel, attempting to make them operate on 50mhz. I'm confident my DC is stable. Additional information include
"I'm confident my DC is stable." Scratch that. I misunderstood the statement: "He has to make the amp DC stable before hooking up the input and output RF networks." 73, Roger AI7RR __________________
Roger, if you have a Pi tuned input it is not easy to neutralize. Your feed back (from the neutralization capacitor) needs to be out of phase with the grid. You could connect it to the input side of
You don't bypass the neutralizing cap. You reduce the value of the bypass cap at the cold end (away from the grid) of the grid tank circuit so that it will above ground for RF to some extent. You con
Roger, it would help if you could draw a schematic and post it on a website somewhere. 73, Bill W6WRT _______________________________________________ Amps mailing list Amps@contesting.com http://list
OK, it has a PI input. I suspect there was originally a swamping resistor from grid to ground and the PI circuit is intended as a low-pass filter matching device to compensate for the grid-cathode ca
-- ORIGINAL MESSAGE --(may be snipped) REPLY: I agree with Vic's comments 100%. The only way to neutralize with a pi-input circuit that I know of is with a coupling coil from plate tank to input tank
I agree with Vic's comments 100%. The only way to neutralize with a pi-input circuit that I know of is with a coupling coil from plate tank to input tank, which I would NOT do. Too finicky to adjust
Sockets in use are Eimac SK-640. 73, Roger AI7RR _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
If you are using the SK-640 sockets, which lack integral screen bypass capacitors, what kind of other screen bypass do you use? Be advised that attempting linear operation of the 4X150 on 50 MHz usin
I've looked at the schematic. As you have SK640 sockets why not modify the design to run "grounded screen" ... like the 144MHz 4CX1000A design in the 1990 ARRL handbook? You would connect B- to the c
"Grounded screen" will work as it did in the Collins 204F-1 and the 208U-3/10 amplifiers,which were neutralized despite using liberal grid swamping. The electron transit time input losses at 50 MHz f