[Elecraft] Chirp with K2/XV222

[Don Wilhelm]

Steve,

I would think your assumptions for the cause may be correct.
BUT -- rather than changing the XV222, I would suggest running a larger 
gauge wire to the XV222 would be the easiest solution. Assuring that all 
connections on the power cord are tight and with very low resistance 
should help a lot.

You could change the reverse polarity protection diode to a  95SQ015 
(Elecraft PN E560009) and it may help some, but I would suggest that 
would be simply masking the real culprit which I suspect is voltage 
drops in your power wiring.

73,
Don W3FPR

On 6/11/2013 6:58 PM, Steve Kavanagh wrote:
> I got a report of chirp when running CW on 222 MHz during the VHF contest this past weekend.
> This has been confirmed by a few others since the contest.  It's quite possible that the various voltage
> drops from the Rover vehicle battery to the XV222 were not leaving enough headroom for the 78L09
> local oscillator regulator.  I am not sure this is the problem, but it certainly is plausible. I am looking
> at various approaches to fixing this, but I wonder if there is anything that can be done to make the
> XV222 a bit less sensitive to low voltage.  For example:
>
> (1) change the reverse polarity protection diode to something with a lower voltage drop.  The manual
> says it's an SG530, for which I cannot find a data sheet....is it the same as an SB530 by any chance ?
> (2) change the regulator to an 8, 8.2 or 8.5 volt unit.  All of these exist in TO-92 format though some
> are getting hard to obtain now.  Would the oscillator start reliably ? Would there be enough LO
> power for the mixer ?
> (3) change the regulator to a low-dropout type.  I can't find any 9 volt TO-92 LDO regulators so far.
> Does anybody know of a source ?  I suppose a tiny SMD board could be piggybacked....
>
> Has anyone any specific info on these ideas or other possible mods ?
>