There was a similar amplifier for sale on QTH.com a while back. The seller was a 6 meter EME enthusiast who appeared to be in the process of downsizing. I suppose with one of those amps on each end o
73, Mike W4EF......... <I've seen earlier parts of this series, but never a rationale for the <existence of such an amplifier.? It's beautifully built, but... <73, Pete N4ZR _________________________
The first article that Jim posted below suggests running TLW. I've been using TLW for years, but recently when I tried to run it for something I was doing at work, I discovered it no longer works on
Yeah, I just check my other Windows 10 desktop and it runs fine there. Both are running the 64 bit professional version. I think the problem may have something to do with the display scaling on the m
I am repairing a Collins 30L-1 and it looks like the armature coil on the T/R relay is open circuit. Is there anyone who sells replacements. The relay is a Potter & Brumfield KR-2916. Someone is sell
Great idea, Jim. I think Ameritron did this on some of their amps. I saw a picture of one recently that had a spark gap on the tune cap. I was recently bringing a 30L-1 back to life and was having pr
Luk, At least for amplifiers I've seen here in North America, the isolation between the chassis metal and the power mains neutral typically come from the HV transformer (and any additional transforme
Luk, Are you using the PA0FRI screen regulator circuit? If so, won't you need more than 360 Vdc input? 73, Mike W4EF................. Could someone please verify J chose the voltage correctly, please
There is a copy of the G3SEK article here: https://www.tmchistory.org/tmc_restoration/PAL-500/power and protection for modern tetrodes.pdf 73, Mike W4EF...............................................
You might try checking with John KF6I at Island Amplifiers. He services Alpha legacy products: https://islandamplifier.com/ I agree that the material is very likely to be iron powder. If so, there is
FWIW, the pertinent technical data for the Micrometals #2 Iron Powder material mix (relative permeability, mu = 10) can be found here: https://www.micrometals.com/products/materials/-2/ If you look a
Hi Jim, My only familiarity with iron powder is there common application in high-Q RF inductors. They are available in a wide range of sizes depending on the power level involved. I don't know if the
If you want to delve into the physical nature of the "dimensional resonance" in ferrites, this PHD thesis by Glenn Skutt is probably not a bad place to start. It's pretty dense with equations, but th
Yes, I've heard of the Snelling book as being a bible of sorts for this sort of thing. I was really surprised to find just now that you can download a copy (411 pages) from the internet archive here:
I just happen to stumble on this sentence when looking for reference information on Iron Powder cores: "Long term operation of iron powder cores above 80 °C can cause a permanent reduction in both Q
If you were transmitting CW or FT8 and your amplifier was adding hum modulation sidebands it would definitely show up on a waterfall of a station receiving your signal as copies of the primary signal
Hi David, I was trying to address a particular comment that Lukasz SP4IT made, which was: /"Also, have you had a chance to see a waterfall of your SSB signal? I wonder if the correspondents can't hea
That is interesting, Jim. Other's have commented that a class AB amplifier should have relatively high anode supply hum rejection. That doesn't appear to be the case for your L4/L7 since the 3% RMS r
Yeah, Steve, the L4/L7 is a grounded-grid zero-bias triode (2x 3-500Z). The constant current curves for the 3-500Z have significant downward slope to them. I looked at constant curves for the 4CX800A
The difference between the case Lukasz is describing and what you are describing, Dennis, is subtle but important. When specifying what level of VSWR a conventionally tuned amplifier can handle, you