Sunday 31 October 2010

Amplifier Update

Well my SRW Linear is back on the Air. A replacement resistor and installation of the spare set of valves got things going although it is not certain  that the old valves have expired. Yesterday I was running the Amp, just "tickling" it with 10 watts drive from the rig, giving me around 100watts out. All went well for a couple of QSOs. Then as I was closing down "pop"! The household mains supply went out (The RCD tripped) and the linear blew an internal fuse again! The Cause? A 1500Pf Capacitor on the 30 meter section of the bandswitch blew .

I have replaced this with 2 3300pf caps in series (all I had) and although it is back working again the linear presents the rig with a High SWR on 30 metres- I guess that is due to the slight difference in capacitance but the internal ATU copes with that OK.
This particular Linear appears somewhat fragile and not up to standard of say some of the Yaesu amps. However I am learning from it and am fortunate that I have helpful and knowledgable local amateurs nearby who are willing to help out.
It certainly appears that I will need to note down the values of the various capacitors in this unit and start building up a stck in preparation for the next failure!


  1. By the looks of the cap I suppose there was no guessing where the trouble was.

  2. Hello kev just wondered if you remember what resistors and caps you replaced in the srw. I have 1 with the same fault and symptoms Ie no anode current. Its an old post so i understand if you can't remember no problem, btw i've read both posts about your loudenboomer . Many thanks 73s nick