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 ? 73, Steve VE3SMA ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
