Yaesu FL-2100B SWR in standby

Discussion in 'Amateur Radio Amplifiers' started by N8VIL, Jan 10, 2016.

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  1. N8VIL

    N8VIL Ham Member QRZ Page

    I don't mean to digress too much off topic, but I found this video while reading some info on standing waves. It gives explanation of standing waves in a mechanical/visual representation. I thought it was informative in an elementary presentation. I thought it might be of interest.

     
  2. WA9WVX

    WA9WVX Ham Member QRZ Page

    You don't mine me asking, "Could the internal SWR Meter be out of Calibration?"

    Dan
    WA9WVX
     
  3. N8VIL

    N8VIL Ham Member QRZ Page

    I am not using the internal meter on the amp for measurements. I have 2 known accurate SWR meters. I am using one between the exciter and amplifier input, and another between amplifier output and load. I am measuring pass through SWR.
     
  4. W1QJ

    W1QJ Ham Member QRZ Page

    Pass thru swr especially at higher frequencies is typical with open frame relays. It particularly gets bad at 6 meters. adding the cap to ground remedies this. The amount of swr depends on the particular relay used and the way the coax is dressed etc. from input to output.
     
  5. G3YRO

    G3YRO Ham Member QRZ Page

    So out of interest, are you seeing the same VSWR on the meter before the amp as on the one after?
     
  6. N8VIL

    N8VIL Ham Member QRZ Page

    After the amplifier it is 1.0 to 1 into 50 ohm dummy load on all bands (80-40-20-15-10). Into the amplifier in standby connected to dummy load 80 & 40 1.0 to 1. 20 1.5 to 1. 15 1.8 to 1. 10 2.8 to 1. I haven't had a chance to put the 33pf capacitor into it yet. You are right (G3YRO) the input wiring to the relay looks a little "ugly" for RF at higher frequencies. I did all the obvious as far as cleaning the relay and connection issues.
     
    Last edited: Jan 13, 2016
  7. WA9WVX

    WA9WVX Ham Member QRZ Page

    How about replacing that input "wire" with RG-141/U Teflon Coax as it's the same size as RG-58/U but has a much higher temperature range and a solid center conductor.
     
  8. W1QJ

    W1QJ Ham Member QRZ Page

    That won't solve anything if the relay inductance is the problem. Put that capacitor like I said and watch the swr disappear.
     
  9. G3YRO

    G3YRO Ham Member QRZ Page

    When in Standby? That doesn't make sense !


    Even the wire from the Tx Input socket to the Relay is a bit long in my opinion . . . but isn't the cable from the bottom of the SWR sensor to the relay just a wire too (and not co-ax)?

    [​IMG]
     
    Last edited: Jan 14, 2016
    W1TRY likes this.
  10. N8VIL

    N8VIL Ham Member QRZ Page

     
    Last edited: Jan 14, 2016

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