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Hi Jim, I've spent more time modelling it now but I'm still not happy with the overshoot with sudden load changes Plus, I've come by an "energy storage" capacitor rated 38uF at 8kV. (It's 22" tall, 6"

You are correct.? A MOV? from each winding...to chassis? is a wasted effort.? ?I didn't think of what happens if the spark gap arced, when the choke is part of a choke input (resonant or not).?

Well then... since what we're REALLY concerned about is keeping the voltage difference between the choke winding and iron core low enough that it never arcs over and causes damage, what about a

I was thinking about a RVS connected diode across the choke..... but Hammond/dahl read me the riot act, said...'don't even think about it'.? ?They are correct of course, since the normal Voltage

Here.? ? ?https://www.ctrengineeringinc.com/contacting-us-please-read/

What is W8JI's email address for ordering parts? Thanks. Jay, K2ZT

DigiKey delivered my Alph 99 transformer exactly 7 weeks after ordering it for a fairly reasonable price. The new one says "Peter W. Dahl" on it and it is STOUT!. NO Hv sag at full output. Good on ya,

I notice in the circuit of the Henry 3K, 4K EHT supply there is a 10H choke, with a 0.2uF capacitor *in parallel*. 0.2uF // 10H makes a parallel resonant circuit at 120Hz, nice trick to up the

I wonder if a VERY careful examination of both the choke and the chassis and choke mounting hardware, including at the mounting holes for screws, might find some sign of soot from such HV arcing?? The

I recently acquired a few Alpha amplifiers that needed repair.? Along the way I decided to test all 10 tubes I had on hand. I put each 3cx400A7 in one at a time, let the filament run for a while to

Thanks Jim, loads of great info here, just what I needed. Your Dahl choke is a beast, wow, I thought mine was a monster, but life has taught me that somewhere, there will always be a man with a bigger

Actually, I applied for membership to that group a few weeks ago, but still haven't heard from a moderator either way. Have been trying to read through the "back issues" of posts in the Archive, but

Hi, I am? looking for Bandswitch Rear Wafer? E4C-N18 for my Alpha 78. Anybody in the group either has one for sale or know where to buy it? Thanks 73 de Arturo, LU6ETB

Dr Alex is alive and well. I bought and paid for some doorknob capacitors just yesterday. I try not to shop anywhere else. 73, Alek VK6APK.

I saw those 4 uh? roller coils. I didn't get an answer back from Dr? Alex as to? what ga wire was used, or condition of them.? I have never ordered anything from him...so have no clue what the

I just did this recently.? I bought a used Dahl? choke (4H,? 3 amps CCS, and 15 kv rated). Weighs 127 lbs and uses the same hypersil core as the Dahl 10 kva plate xfmrs...which also weigh 127

There is an Alpha group here on "Groups.io", rather specific to the 9500, but I've seen inquiries regarding other Alpha models. In addition, Glenn Pladsen (AE0Q) often posts replies to issues posted

I've built many EHT supplies over decades but have always used capacitive only, ripple-filtering. Sitting below my desk for many years, is an inductor rated 7,500V, 0.85A CCS, 10 Henries. It came from

RFP will not sell 3-500Z tubes to overseas buyers but I bought 4 of them through their Ebay store, no problem. They will send them anywhere in the world. Go figure. 73, Alek VK6APK