Good idea with the scope, thanks. I do have a 100:1 5KV probe, but haven't used it on a 4KV supply before. I have to admit I'm nervous about that. I just bought a DSO and the new scope smell hasn't w
So what do you all think about using an RF Parts RFC-3 (225 uh 1.5A 4KV) plate choke as the safety choke for a large HF amp? The supply is 4KV at up to 2A, bridge rectifier with 32uf of filter. Altho
Hi Carel. I don't think I can get enough inductance with any reasonably sized stack of powdered-iron cores, but perhaps ferrite. I'll check into it. Thanks, Jim N7CXI ________________________________
The "talking" or "chattering" 3KA choke issue is resolved. Believe it or not, what fixed it was one of the following: (1) Replacing the original carbon comp resistors in the parasitic suppressors wit
I can see doing those things as a learning experiment, but if the goal is an inexpensive load you can get NOS Florida RF 250-watt flange mount resistors from Henry Radio on eBay for $24.95, or 800-wa
Sorry, make that 3200W instead of 3600W . I apparently can't multiply in my head any more. 73, Jim N7CXI -- I can see doing those things as a learning experiment, but if the goal is an inexpensive lo
I have a 3KV, 2A CCS transformer, and 32uf of filter. What's the current state of argument for appropriate bleeder current? The last time this came up I seem to remember seeing everything from "HV sa
[forgot to CC this back to the list] Thanks, Jim. I believe your comments about heavier bleeder current being a carry-over are probably true. I'm going to pencil in four 100k, 20-watt resistors with
Thanks to all that replied, on and off the list. It seems that the sum of popular opinion is: (1) With a C-input filter, bleeders are a safety issue only, otherwise just generate heat in the room, ra
Has anyone tried the Elecraft W2 bar-graph wattmeter for tweaking their legal-limit amp? I read somewhere that the peak-hold is something like a second. If so, probably too long to be useful for my p
I do some QSY'ing up and down the band going from this group to that one, and rather than switch off to the dummy load I'll sometimes tweak for the freq change on SSB or AM voice peaks as I transmit.
You could determine the light-current inductance by hooking it in series with a suitable capacitor, then using an audio generator and a scope to find resonance. It's most likely they are indeed swing
Correction: Make that a voltage dip, not spike, sorry. I was thinking of series resonance in a normal circuit, not as wired on the bench. In any case, where the meter does something interesting is th
Is there any reason I shouldn't getter a set of GU-74B's in-place in the amp with blower air, filaments hot, and with grid and screen bias applied, but with the plate caps lifted? The amp in question
Hi Russ, That seems to be the most common opinion, thanks. The annoying part is that I gathered all the parts for my DIY HiPot tester over a year ago, and never had or took the time to build it. I've
I don't really know what they use either, which is annoying. "People say" it's on the cathode, which certainly would be convenient. LY1DQ's datasheet says the tube is indirectly heated, which makes i
ChartPak has black dry transfer lettering in various sizes: 8-12pt (up to 1/4") http://www.pcbsupplies.com/servlet/the-318/Dry-Transfer-Lettering/Detail 16-point (5/32") on closeout http://www.pcbsup
I haven't had the privilege of hi-pot testing a tetrode before. Just based on how they're built, it seems to me that plate to screen would be be the most likely thing to test. Comments? Also, what wo
Never mind, I should have looked at the archives. 73, Jim N7CXI _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
If there's room where the duct exits the rear of the amp, a "noise sweep" will reduce noise - at least that conducted through the air in the line - substantially. Take a 90-degree dryer hose coupler