I really hope this isn't the problem, but many years ago I heard
something like this. Interestingly, this only happened when the DX-40
was in standby (HV center tap open). I never could figure it out, until
one night there was a loud braaapp from the receiver, and within a few
seconds, the power transformer "released its smoke." I'm not familiar
with the SB220, but because yours happens with supply on, it is likely
to be something else. There was a good ending, as this was long enough
ago that Heathkit still had parts for this rig available. I recall the
price was about $7.50 in 1963 dollars. I'll leave it to others to
calculate the price in today's dollars.
Chris, AB6QK
Message: 5
Date: Sun, 20 Jan 2019 09:02:21 -0700
From: Steve London <n2icarrl@gmail.com>
To: amps@contesting.com
Subject: [Amps] SB-220 tick,tick,tick
Message-ID: <11ac7e89-8dcd-406c-d009-9616b6913697@arrl.net>
Content-Type: text/plain; charset=utf-8; format=flowed
I have an SB-220, of unknown lineage.
While using it, I noticed that on receive, listening on my receiver, I
was
hearing a strong tick, tick, tick sound, about 3 ticks per second. With
a little
experimentation, I noticed the tick rate was higher in the SSB position
than the
CW position. At audio frequencies, I localized the source to the HV area
of the
amp. My guess would be filter capacitors, rectifiers or equalizing
resistors. A
few more data points - the equalizing resistors are not the original -
they are
100K, rather than the original 30K. The electrolytics are Nichicon
200uF, 450
WV, 85 degree C. That's probably not original, either. I don't see any
cracked
resistors. Best course of action ? Replace the electrolytics ?
73,
Steve, N2IC
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|