Thanks for the on and off list responses. Advice ran 50/50 for and against the polyester caps for amp by-passing. I don't want to put anything in there unless I'm sure it will achieve my goals, so I
Tuning is VERY touchy. You really have to have the loading right or the screen current is excessive in either direction. None of my 4CX1000A or 4CX1500B amps were all that touchy, from 1.8 to 144 MHz
My weak mind is trying to understand the problem. Maybe it's something to do with the imbalance of the antenna? I ran QRO significantly exceeding this definition through N connectors at 144 MHz for m
I would like that have info too. I spend WAY too much time soldering PL-259s. Also, what about stripping the cable for installing the crimp PL-259s? is there a tool for that? If so, how necessary/imp
They are available from many suppliers. I have been running a "healthy" 1.5 kW through them at 50 MHz for 6 or 7 years without any trouble so far. SWR is typically 1.5:1 but has been over 2:1 with ic
Jerry, It often seems at though the only builders here are those who turn out works of art. But there are some who build functional amplifiers that aren't pretty. My main reason for amp building is i
I presume this refers to desktop amps. My early ones were, but everything today has to be rack mount. No space, so everything must go vertical. If you are willing to take the time to learn to use the
After doing some simple calculations, I think you only need 6 positions on the tank switch. 160, 80, 40, 30/20, 17/15, 12/10. That is exactly the way my amp is built. I'm sure there will be comments
I don't know what the "recommended" blower is, but bear in mind slow speed blowers can be much less noisy than high speed ones. They tend to be physically larger, however. On some prior amps I used h
Hey amp gurus, I have been going around and around with a recently rebuilt VHF amplifier that is refusing to work correctly. To help me think this through, I want to be sure I am understanding how so
I am just going over things trying to sort out why the amp keeps self destructing. Hopefully a hi pot tester I am building may give some answers or at least clues. For now, I believe my screen regula
On 10/26/2016 03:39 PM, Gene May wrote: Suggestions by Bill and Gary K4FMX and others to put a resistor from the screen to the cathode, such that the resistor will pass at least the maximum "negative
So, moving along from the topic of screen grid voltage regulation and direction of current flow, here is my other/next question... Suppose you have a 4CX1500B sitting in the middle of a half wave pla
I use Teflon sheet and nylon machine screws and lock nuts. Initially I was concerned about heat with the nylon hardware but I have not had any problems. Here is a chimney for a 4CX1500B which has bee
On 10/28/2016 08:43 PM, John Lyles wrote: With respect to earth, the RF voltage swing is largest at the center of the tube. But across the dielectric of the blocking cap, the RF voltage should be low
Arcing somewhere which kills the zener diodes in the screen supply. Does it always happen in the same place? I don't know where it happens. That's the problem. I am asking questions in an effort to i
I have never worked with a GS-35B and it has been almost 20 years since I had any triode experience. I have a VHF amp with a single GS-35B and a home brew bias board taken from the G3SEK triode board
Kill the bias and try it. Aha! Thanks for the wake up call Alek. At 500V with zero bias it is drawing 100 mA and at 1 kV 200 mA. It's alive! As a follow-up on other comments... I will be running this
Just looking for a reality check here. I am trying to get an amp running. It was not built by me and had apparently been sitting for quite a while. Everything seemed to be working but the input SWR w
Thanks to everyone for the input. I am just getting acquainted with triodes as I have very little prior experience with them, none in the last 17 years. I have rebuilt the input circuit and moved the