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It's been a few years since I made a doubler from the 1st board. If it's the same board, I'll strip the board down and reinstall diodes & caps. I attempted to find the board on your website but did not locate. Quality board thick plating that withstands re-soldering mistakes lol. CTR...

My 4cx300 tubes are starved for plate current. After years of working on this, I may as well do it right. I'm replacing the entire HVPS. Voltage Doubler replaced with a FWB driven by a different transformer rated for 1800v @ 400mA (Heathkit 54-30). No more combo trannies so I also ordered a 6v...

Thanks for your time to comment. I need to re-read your first para a few more times to fully understand it but I will do so. The very idea of a transformer for RF is fascinating. I looked at the Pride input on paper but could not decipher the diagram. Think I need to see the part, visual...

Been winding Baluns, tidying messy wires & tweaking this & that. Replaced the small core with 1-1/8" core (still mix 43). I'm focused on the RF Input section now. Changes take time to try and what works on a DL is not always good on an antenna. The attached "now" pic file is a diagram of...

$160 for a new Cantenna?? I'm on my 3rd can from a 1980's Heath Cantenna. I use Baby Oil and it smells OK.

I noted the minimal nature of the Screen supply design of the Tokyo HyPower 4cx diagrams when compared to the rest of their circuit. I'm learning less is more efficient when it comes to RF.

PRESS FIT PTFE INSULATED FEED-THRU TERMINALS on eBay at https://www.ebay.com/itm/363996444302?mkcid=1&mkrid=711-53200-19255-0&siteid=0&customid=link&campid=5336136228&toolid=20001&mkevt=1 20 for $13 including delivery. Cambion brand with datasheet. .22" insert diameter. Several Sellers. The...

Last few days rewired the input section. It was very sloppy, too many parts. I'm surprised it worked at all. What's that saying about a monkey with a typewriter composing Shakespeare? Deleted a paragraph about input tuning. All progress stopped a week at least. Small feed-throughs on blower...

Some hand from above reached down to adjust the market. Sounds about right. Internet held such promise in the early '90's.

Applied power today after rebuilding Tank & band switch. Revisions included new plate choke (series resistance drop of almost 4 ohms), new Load cap and a band switch/pi rebuild/revisions. The resultant optimal Tune and Load settings for max PO on 28.340 into DL are improved to the extent that...

For the life of me I cannot find that Item again. The paragraph above was a cut & paste from the listing itself. Found it late last night browsing ads. It ws cheap <$200 and had switched inputs for each band. Homebrew but small and finished in blue/silver. Something I'd never seen before...

Interesting Homebrew at: https://www.ebay.com/itm/334888084436?mkcid=1&mkrid=711-53200-19255-0&siteid=0&customid=link&campid=5336136228&toolid=20001&mkevt=1 The base amplifier here is an “ST” DB-2933-54 test bed for it’s RF POWER amplifier using 2 x SD2933 N-Channel enhancement-mode lateral...

I think I understand: The efficiency of swamping makes an auto tuner impractical. My bad, I keep trying to re-invent the wheel.

Thank you for your reply. For chuckles I added 2 tiny ferrite beads near the plate choke. I'll find out if the Ohmite choke can take the voltage soon. It measured 2.5 ohms while the old choke was 7ohms. My antenna system cannot handle 80 so that's a no go area for me. Waiting for the 5w...

Rebuilding Eldico band switch. Picture is of the contact connecting switch rotor to coax. Note the lump of silver on tip.

Thank you for the Replies. I'm determined to get at least a reliable amp from this effort but adjustments and revisions go on forever. Trying to follow the 4cx amp diagrams from Tokyo Hy-Power and Pride whenever possible. High Plate Resistance of Tetrodes I replaced the single 100R anode...

I got lucky and found a relevant article on Tetrode Plate Resistance fast. https://www.electroniclinic.com/tetrode-construction-and-characteristics-in-electronics/ Sped-Read it just now and it (Revised text Italicized) appears relevant. Thanks for the redirect Nomad. Higher plate voltage may...

Plate Resistance: Thought I was getting somewhere then, I learn there's a concept at play I know nothing about. A good day to you too, lol. Guess I have more reading to do. I do have a band switch problem. I'm keeping the original coil dimensions for the Eldico 4cx250 box (another reason...

I’m still running the 300a tubes as I cannot reach their published max output. Buying two 300y tubes (400w rating) was wishful thinking it seems. Made several mods and improvements but I’m still restricted to a DL although I managed to move amp from the work table to the operating location...

Soon on the primary cable run. I've moved tetrode amp to my operating location several times only to move it back to work area for some mod or adjustment. New rg8x patch cables & hardware needed so I can switch Tets in & out w/ATU. It takes time to maintain a station that can reliably...