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MFJ 998RT Repair and Mod - failed K1 Relay and R121
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- čas přidán 20. 07. 2018
- This is an alternative repair to the one suggested by JH3CLV who fabricated a heat sink for R121. This video and repair was done in 2014. Unfortunately, since then JH3CLV has suffered 2 more failures. However, my tuner has not suffered a failure for 4 years since my repair. However, no inference as to the efficacy of my approach should be taken from this experience as I most likely have been just lucky!
Links to JH3CLV discussion on issue:
radiovillage.bb...
www5a.biglobe.n...
www5a.biglobe.n...
Any comments or suggestions as to why this situation occurred and what are better repairs and mods are welcome. One mod I do intend to make is to use heaver gauge leads to the resistor than the ones shown.
73,
Frank
Just received my 998RT today (May 25, 2021). Have not unboxed it yet. If my newer unit still has the 15 watt resistor without a heatsink on it I may do a bit of preventative maintenance and use your 100 watt resistor solution before hooking it into my station.
Thanks for posting your solution!
Bill - W7JZE
This is not first time when MFJ sucks… But nice modification !! 👍😊
Great tip. Thanks, KU3X
This resistor is most likely carrying high frequency (to be investigated)In this case it is not a bright idea to connect it with such a long wire
I have a problem with the mfj 939 tuner when the swr indicator is on sometimes and the K1 relay sometimes works sometimes doesn't work, is the problem the same as your tuner ?
How were you able to figure our which relay was bad? 😀😀