Thread: FT480R repair
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Old August 8th 07, 05:53 PM posted to uk.radio.amateur,rec.radio.amateur.equipment
Brian Reay Brian Reay is offline
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First recorded activity by RadioBanter: Jun 2006
Posts: 42
Default FT480R repair

"Anonymous" wrote in message ...
I need to replace the T/R relay on an FT480R.
(Intermittent Rx, curable by a quick blip on TX)

I don't have an exact replacement, so I'll use a
Varley 12V relay, with suitable mods to the driving cct,
and dangle the relay in the space behind the front panel.

Is there a knack to removing the main board without first
unsoldering the numerous connections? (i.e., can it just
be a tedious job, or must it be downright finicky?)

There is a second pair of change-over contacts on the
relay, but with both outputs wired together...this would seem
to suggest some form of muting effect that deals only with
the T/R or R/T changeover period. Any ideas?



From the circuit diagram:

The relay switches two things:

Antenna (Rx/Tx)

13.8V to the Tone unit.

One side of the relay coil is to the 13.8V internal rail, other side is to
the Main Unit and, unless it is very convoluted, isn't connected to either
set of relay contacts nor do the two sets of contacts seen to be connected
to each other.

I've done one of these before and, as I recall, "pin for pin" relays were
available- I think Farnell.