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I have one of these Ill be selling at NearFEST this weekend. I have the technical manual. I also have a 50v50a switcher to power it. It needs love from a good tech. It is a beast when operational. 73

Hi Jim doing the sweep thing gets you in the ball park but you need to be under full power to tune the input. ?You just need a little tweaking for the 572b tubes. ?Ameritron never adjusted those

Dear Jim, While I was describing the method for employing a non-inductive resistor in place of the tube circuit in a grid-driven tetrode scheme, the methodology carries into basically the same steps

Hal, I'm relatively new to tube amplifiers and I certainly don't know all the jargon. I assume you are meaning a " Bruene Bridge" as in Warren Bruene's capacity-bridge from the 50's? Bread-slicer as

Jim, For Joy! Connecting the SpecAn/TG to the amp's output spigot, once the Input network is run through a VNA plot set on the input (with the N.I. resistor going...) you will then be able to detect

Jim, In my a-building Grid-Driven 2-holer Tetrode the Breuhne bridge used for Neutralizing the tubes has a small roller inductor and both a fixed and variable bread-slicer. Since the Input network is

Lou, Thank you for your suggestion. I was thinking of doing the same. I have several capacitor values lying on the bench to do just that. I've read that some have suggested using a VNA to sweep the

Hal, Yes, have a nanoVNA and spectrum analyzer with tracking gen. Can you please explain the methodology you propose? I'm curious to know how you use your VNA to test the input circuit of tube amp. I

Sure. But before you do that, make sure it is actually the vernier drive that is the problem. The capacitor itself may have a "tight spot" on it that is making the drive hang up. Most of the time,

Jim, You might need to add about 10pF off of the cathode pin(s). Do you have a VNA? They are swell gear to expose tuning glitches. Hal W4HBM

The position of the slug tell you a big story. ?Ultimately you would?want the slug to Bering inside of the coil windings when the SWR dips the lowest. ?That would indicate there’s enough of

I'm working on a used AL-811 for a friend. The 811 tubes were bad, so I replaced them with some Penta Labs 572b tubes (A whole another adventure). I also replaced the tube sockets, and installed GDTs

Hello, Has anyone had to replace the vernier drive on the load control of any of the Ameritron AL series amplifiers? Thanks & 73, Garry - K4OR

Ahh yes.? Aerotron used the 5894 in their base stations along with the 6360 in their "lunch boxes".? IIRC, somewhere along the line they used the 8643 also. Andy? K9ATX

Amperex had a tube lineup, mostly 9 and 11 pin receiving miniatures that were serviceable, but they were out of their league when pushing RF Power. (For a minute I confused "Amperex" with "Ampex," who

Amperex had roughly half a dozen of these push-pull tetrode types in their product line back in the day, probably all targeted for the VHF/UHF land mobile radio services. All were single-ended input,

" The comment in the blurb about frequent replacement of the tetrode finals make me wonder if the designers were Tetrode Men." Yes, it's easy to imagine that development lab had some "politics" that

Tuesday, April 29, 2025; 0944EDT (UTC-5) Dear Tim, The comment in the blurb about frequent replacement of the tetrode finals make me wonder if the designers were Tetrode Men. I'm struggling with

Tuesday (Mardi),29 April 2025; 0940 EDT (UTC-5) Dear Francois, An excellent piece of research! "C'est un fabrication ancienne..." Your comments are so well received here. Hal Mandel W4HBM

Seems very likely the site used this Pye T30AM/FM set in the 1960's 1970's. They used QQE0312 final stage and the former Pye engineers forum says these were well known for needing final tube