Hi folks, I have an otherwise excellent black-faced Alpha 77 whose blower is starting to growl a bit here and there. No doubt this has been covered in depth elsewhere, but not having found it is ther
I'll propose that considerable effort be put toward ensuring long-term reliability. I haven't met many switching supplies that would hold up to 20 or 30 years of intermittent use without failing. Low
All this talk about seals, temperatures and sensors has me wondering what would be a reasonable, conservative guessestimate of the maximum safe exhaust temperature on an Alpha 77? (single 8877, groun
Thanks, Bill. That idea also gets around the issue of using a potentially RF-noisy DC motor, as pointed out by K7RDX. Short of the complications and overkill of a single-phase VFD, a couple of speeds
I've been convinced at least my #2 Alpha 77 deserves an EBM-Papst blower upgrade. #1 is still completely original, so for now I'm just going to do the bearings and see if I can find ways to use a lit
Thanks for all the replies, guys. I believe the top pick was Allied, followed by Newark and Galco. Very much appreciated! 73, Jim, N7CXI _______________________________________________ Amps mailing l
So why did Heath do it then? (Chokes et al) Inquiring minds want to know 73, --jim Sent from my BlackBerry® wireless device from U.S. Cellular The Grid is far from "well grounded." With 220 pF in ser
Oh the torture... For usn's that don't have the SB-220 manual, anyway. Or, come to think of it... do I? This might require a romp through the stacks. That usually turns something up, although rarely
Garden-variety "Formula 409" spray cleaner works for me. I've had good luck soaking cases, chassis etc. with it for 15 minutes or so, then either rinsing with clear water or wiping down with a fresh
Any fatal flaws or (significant) bad design decisions in the Henry 3K-A? After squinting at the schematic available at the BAMA site for a while what I see so far is: (1) A rather unusual "manual" so
Thanks to Dave K6XYZ, Steve AB5MM and Phil K5PC for the very helpful responses. Phil, you're right. I am truly interested in how it works, but I'll also admit an ulterior motive as I'm working on buy
I need a HV probe with reasonable accuracy for working on this growing stack of hamplifiers. I have a Simpson 260 and know some of those pitfalls, and a 40KV CRT chicken stick that's probably +,- 20%
Thanks, guys. Looks like I can get the Fluke 80K-6 probe for less than $100 new, so it's hardly worth messing about with resistors, boxes, etc. 73, Jim, N7CXI ________________________________________
Good point. The 80K-6 is designed to work with a 10M input impedance. I have two meters that should qualify, but if not I may be able to sneak up on a 77-4 if I do it ... quietly ... without Her (or
Great tip, thanks! Just clicked the clicker and bought 2 sets. (I have a friend with similar interests) 73, Jim, N7CXI _______________________________________________ Amps mailing list Amps@contestin
The Henry 3K-A I just picked up (loooonnnggg drive!) has a set of what were 12 years ago "fresh" 3-500Z's with it. The amp and tubes have been sitting in the OM's nice, warm, dry shack for 12 years w
Or, how about putting 50M in series with each anode cap and then monitoring the anodes for voltage drops? (arcs) I don't know if limiting the current that severely would allow arcs that might occur t
Thanks Ian, Carl, others off-list. I can lift the blower leads and power it separately, disconnect the anodes and use a 240V Variac I bought for these kinds of tasks to run things up slowly. I haven'
If you wanted a precision RF instrument to last a long time without significant component drift, would you use carbon film or metal oxide resistors? Assumptions: (1) Little to no RF power dissipated