If it happened on transmit, I'd assume RF but it's only on receive.
It doesn't stop when I disconnect from the Ext Sp jack so if it's a
ground loop, it's not via that route (ACC, CI-V, and DC are still
connected ...). And I'd expect that to be constant and this is
intermittent. Can go for some time without acting up, actually.
Could be the relay. Given that percussive maintenance "fixes" it,
it's not a bad avenue to pursue.
Peter
On Sat, Jan 4, 2025 at 6:33?PM Burt K6OQK via groups.io
<biwa@...> wrote:
Peter,
I've never experienced that problem with my 746PRO, but if it did,
the first thing I might suspect would be filters in the DC
supply. Possibly a relay isn't seating properly? I don't think it's
a ground loop, but then again, I suppose that's possible.
Just some random pondering out loud.
Burt, K6OQK
At 02:35 PM 1/4/2025, you wrote:
Every once in a while, like say if I've been casually operating in
RTTY Roundup, some relay starts buzzing in the radio. It's worse when
the external audio jack is connected to the audio mixer but still
there.
I pull audio for digital modes off ACC(1) and that audio is not
affected - stations are still printing, even when the relay is
buzzing.
Percussive maintenance fixes it for a while, but that's loud enough
(picking up the front of the radio and dropping in 2 cm to the shelf)
to annoy the dogs, who bark, which annoys my SO ...
RL740 on the schematic, near J740 (EXT Speaker jack) jumps out at me
on the schematic in the SM but ... well ...
Anyone else have this issue or hear of it?
--
Peter Laws | VE[23]UWY / N5UWY | plaws0 gmail com | Travel by Train!
Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California U.S.A.
biwa@...
K6OQK
--
Peter Laws | VE[23]UWY / N5UWY | plaws0 gmail com | Travel by Train!
Peter Laws
Burt K6OQK