Could you move them up instead by 2.035 MHz and hit 29.000
MHz OK?
Is there still any AM activity cenetered around 29.100 MHz also?
On 3 Apr 2006 at 22:20, Mike Duke, K5XU wrote:
Most of the older 23 channel units used a mixing scheme which involved one
set of 4 crystals, and one set of 6.
The standard conversion was to shift the set of 6 crystals up by 2 mhz each.
Back then, the crystals were cheap. Now, I doubt you will find them for less
than $10 or more each. Of course, you could only change one or two crystals,
and you would have a similar number of new frequencies (4 per crystal).
Moving these crystals upward by 2 mhz placed channel 1 at 28.965, etc. As
someone has already mentioned, this pattern skips right over 29.0, but does
fall onto 29.005 for channel 4.
The later 23 channel pll units, and every 40 channel unit that I saw from
the late 70s and early 80s could be converted by moving one crystal upward
by whatever amount you wanted to move the rig.
I have a 1980ish Sharp 40 channel rig converted this way, using the standard
2 mhz upward move, and it works great when the band is open. I bought it
from a BC engineer who did a really neat job with the conversion, and it is
otherwise unmodified. My first contact with it in 1998 was with a kh6.
Someday, I may ask someone to add at least one more crystal, 5 khz higher or
lower than the one currently in the unit. This will give me 40 more
channels, and allow operation on 29.0, 29.010, etc.
I bought a new pll board for a late 90s Maxon rig, and it fell flat as a
pancake. The receiver worked fine, but the transmitter wave form and audio
were awful. Having already spent more money that the thing was worth in the
first place, I scrapped it and bought an HTX10.
It's amazing what the converted cb sets will do with the right band
conditions. If you have one, drag it out, change it over, and have it ready
to go when the band comes back. If nothing else, it will be a wonderful
monitor complete with a good squelch circuit.
Mike Duke, K5XU
American Council of Blind Radio Amateurs
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