On Sat, 2007-04-14 at 16:33 +0000, H. M. Motley Jr. wrote:
> I have developed an intermittent problem. At times my Paragon with neither
> TX or RX on 18 and 15M or at other times 12 and 10 M. From looking at the
> circuit diagram it appears the trouble must be in the low pass filter board
> where the appropriate LPF is selected by relays which are energized by the
> "T" voltage which is applied to the proper control line. I notice the two
> relays for each LPF are wired in series. When the trouble occurs I hear a
> relay kick in and later I hear a relay stuttering. Finally it may engage and
> things work properly. I notice all control lines are buffered by relay
> driver U1. Has anyone had this problem and solved it? Was it U1 or the
> relays? I never have this problem on the lower bands. Perhaps I should
> replace all 4 relays for these two LPF's? OR maybe there is some other
> problem? Any suggestions would be appreciated.
>
> Puck, W4PM
While I have no experience with the Paragon, I'd first check board
grounds that are often through the board mounting screws. Tighten them
all over the radio.
Then I'd suspect U1, but I'd be checking relay coil voltages with a
voltmeter then tracing the circuit to find an open.
Some TT radios have suffered from bad contacts on cables and pins going
to boards. Some use insulating displacement instead of hard crimped
connections. Those may benefit from applications of a fraction of a drip
of DeoxIT with a little sliding to clean the pins and the crimps.
--
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer
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