[Heathkit] HW-101 T/R RELAY

[Ed - K9EW]

UPDATE:

1)  I noticed that this problem (relay cycling on and off) doesn't seem to
happen in the TUNE mode, only in the CW mode and only when the plate
current gets above 150mA.

2) It's also not consistent.  Sometimes it happens, and sometimes it
doesn't.

Any suggestions?

-ed, k9ew

On Mon, Aug 17, 2020 at 5:30 PM Ed - K9EW <k9ew57 at gmail.com> wrote:

> Still working on my HW-101, but making progress.
>
> I took a break when the T/R relay (RL1/RL2) started dropping out when I
> increased the Drive level so the plate current was around 150mA.  As I did
> this, the B+ would slowly decrease and I thought the Power Supply may be
> sagging such that it couldn't hold the T/R relay in.  Then the relay would
> drop, the B+ would rise, and the relay would pull in, etc.
>
> I couldn't find anything obvious, so I thought I'd rebuild the HP-23A
> Power Supply since I'd planned on doing that anyway.  Well, that wasn't the
> problem - but the ripple looks great now 14Vpp),
>
> The T/R relay is still cycling on and off when I exceed approximately150mA
> of plate current.  Watching the B+, that corresponds to around 660V.
>
> Any suggestions?
>
> -ed, k9ew
>