[Amps] UM4001CR pin diode source - or Alpha 86 vac relay mad

[Bob Wilson, N6TV]

If the receiver goes dead when you switch the Alpha 86 from transmit to
operate, it usually means the LittleFuse on the receive pin bias board has
opened.  Check that first.  It's easy to replace; just remove the top
cover, and it is right there, near the center of the rear panel.  I had to
replace that fuse several times, usually after transmitting on 160m;
nothing wrong with the PIN diodes.

73,
Bob, N6TV

On Fri, Aug 7, 2020 at 4:27 AM Chris Wilson <chris at chriswilson.tv> wrote:

>
>
>   07/08/2020 12:07
>
> I have an Alpha 86 here with suspected TX / RX switching pin diode
> failure. The amps TUNE function is suspect, and switching between
> standby and operate gives a vey attenuated RX signal in standby mode.
> In TX it seems to operate, TUNE display aside, normally.
>
> The manual's schematic shows them as stud mounted UM4001CR devices. I
> am unable to source these, does anyone know of a current source for
> them please? Alternatively does anyone have instructions for
> conversion to using two vac relays? Fast CW is not required, and the
> noise of the vac relays not really a concern. Thanks.
>
> --
>        Best Regards,
>                    Chris Wilson.
> mailto: chris at chriswilson.tv
>
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