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Yaesu FL-2100B SWR in standby

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

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  1. NN2NN

    NN2NN Ham Member QRZ Page

    Thanks Max. I found your post on eHam and to the tee, that is my issue. Intermittent high input swr. The next day it would be gone... make a few transmissions and it would return. Now it seems always there and has progressed to most of the bands. So did you just replace C213 only or have you done more? Also, do you think the mica's are ok in that they don't go bad or is it just the ceramic caps?

    Steve NN2NN
  2. G3YRO

    G3YRO Ham Member QRZ Page

    Just come back to this thread . . .

    People keep going on about the big Relay frame adding inductance, and therefore affecting the VSWR on the higher bands.

    But the point I keep making is that's not the main issue, as it's only about one inch long !

    The antenna wire going to and from the relay is about 4 inches long as I recall . . . so that will have a MUCH more serious effect than the relay itself!

    Much better to replace the wire with Coax . . . I would even by-pass the internal SWR Sensor if you don't use it. (I always leave my meter on Ic anyway)

    Roger G3YRO
  3. VE3TMT

    VE3TMT XML Subscriber QRZ Page

    Hi Steve,

    I only replaced C213. Never bothered with any of the others. My input SWR is under 1.5:1 on all bands so I'm not too concerned,but at some point I am going to order the entire set of caps and replace all of them, whether they need it or not. Just not on my priority list at the moment.

  4. G1XRJ

    G1XRJ Ham Member QRZ Page

    Hi I just found this thread, I have exact problem to the letter>
    Hi input SWR in bypass, into dummy load - getting higher, 21, 24, 28 mhz

    I see the fix was to add a 33pf cap, - could someone explain in simple terms (ideally with pic) where to add it?

  5. W1QJ

    W1QJ Ham Member QRZ Page

    Very simple, go to your antenna relay and look at the terminals. You will see a jumper wire that connects one contact to another in the NO position. Solder one leg of the 33pf there and the other to ground. Done.
  6. WA4SIX

    WA4SIX Ham Member QRZ Page

    My understanding is that the capacitor cancels out the inductance of the relay & wiring. Is that right?

  7. G1XRJ

    G1XRJ Ham Member QRZ Page

    I see a past post stated from the jumper on NC contact ( NC would be bypass would it not)... please confirm

    Thanks for your help, Lou
  8. W1QJ

    W1QJ Ham Member QRZ Page

    Sorry about that, Yeah NC to NC, there should be a jumper wire. Just solder a 33pf from that jumper wire to ground. Then check the swr. If it is still not 1 to 1 you can try different values like 27pf 35pf. Usually 33pf does the trick. And yes, it cancels the inductance reactance of the relay contacts and wiring.
    WA4SIX likes this.
  9. G1XRJ

    G1XRJ Ham Member QRZ Page

    Thanks Lou,

    I've order a a 33pf - but also a coupe of 15pf, and a 2.7pf, so I can play around +/- around 33pf
    I'll post the result

  10. G1XRJ

    G1XRJ Ham Member QRZ Page

    Here is is pic of my relay in the FL2100Z>
    The coaxial comes in on top right (NC contact) I do not see any shorting bar / jumper wire across to the opposite NC contact>
    Where do I connect the cap?, from the arrow to GND?

    Attached Files:

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