>My otherwise excellent 87A is too often out of service due to PIN-diodes
>breaking down.
>
>Has somebody ever made a modification with vacuum relays instead ?
>
I have not, Rag, but this seems like a good idea since PIN diodes are
easily shorted by lightning and by high SWR. However, for >40wpm CW,
relays are not fast enough. Modifying with high-speed relays also
presents an opportunity to remove the RF-actuated T/R switching and use
a transceiver-actuated electronic cathode bias switch (ECBS). This will
result in the bias switching always being in perfect sync with the RF
switching, which will stop the tubes from being switched in and out of
linear bias in the middle of soft-syllables and making rough-sounding
audio.
good luck
>
>73 HNY
>
>Rag Otterstad LA5HE also JW5HE OZ8RO
>located in Telemark - home of skiing.
>
>My antenna "farm" can be found on HTTP://no.photos.yahoo.com/la5he when you
>click on Radio.
>
>
>Take a look at: http://WWW.visitTelemark.com
>
>or http://www.visitnorway.com
>
>_______________________________________________
>Amps mailing list
>Amps@contesting.com
>http://lists.contesting.com/mailman/listinfo/amps
>
- R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
www.vcnet.com/measures.
end
|