Yaesu FL-2100F

Discussion in 'Amateur Radio Amplifiers' started by K6GB, Jul 18, 2018.

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  1. K6GB

    K6GB XML Subscriber QRZ Page

    I picked this up awhile back and I'm just testing it. I'm only getting about 350 watts out with 80 watts drive on 80m,and progressively less as I go up in frequency. The plate voltage is right but I am not getting a very pronounced dip in plate current. I'm thinking tubes are bad, seems that everything out there is Chinese or used. Any tips? RF Parts only has Cetrons, I assume nos, but $200 each, I can order matched pairs of Shanguan tubes for about $120 or DX Engineering label for about 180 a pair.
     
    W4MJR likes this.
  2. AI3V

    AI3V Ham Member QRZ Page

    What is the DC input power ?

    If it's low, you probably have flat tubes.

    Also, do you have a good vswr on the exceiter going into the amp? Be sure you really have the drive you do.

    But I would lean towards tubes in a unknown amp.
    Rege
     
  3. G3YRO

    G3YRO Ham Member QRZ Page

    I presume you are testing this into a Dummy Load.

    As Rege askes, what is the Input PA Current when you have maximum power out?

    But it probably IS bad 572Bs . . . most people hold the Tx button WAY too long when tuning up. Do it in 2-3 second bursts, and the Valves will last a long time!

    I have found the Chinese-made 572Bs as good as the Cetron ones . . . and certainly excellent copies. (I have always bough them direct from China, as they're much cheaper)

    Certainly DON'T try using the Russian 572Bs in these Amps . . . they are very different !

    Roger G3YRO
     
  4. K6GB

    K6GB XML Subscriber QRZ Page

    Ok, input current is roughly 200ma. and yes I'm using an mfj oilcan dummy load, input swr appears ok. I've heard about the Russian tubes, but the Chinese seem to be very reasonable, and I can order them on ebay. I pulled the covers off and everything appears clean and dust free, it was an estate sale and a club was selling off the stuff for the widow.
     
  5. G3YRO

    G3YRO Ham Member QRZ Page

    Yes, that's about HALF the input current you should be getting.

    What often happens is ONE of the 572Bs gives up . . . try unplugging one, and then the other. I bet you still get the same power with the one good Valve !

    By the way, when both Valves are working properly, this amp usually requires a full 100 watts drive for full power output.

    (I'm sure you know about fully discharging the HT Capacitors before touching anything . . . and also not turning it on without the safety discharge rod in the PA cage depressed!)

    Roger G3YRO
     
  6. K6GB

    K6GB XML Subscriber QRZ Page

    Yes, I have always had a healthy respect for high voltages.
     

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