If using a PTO from an Omni V or VI, that in those radios tunes from 5.5
to 5 for tuning up a band, 9 (IF filter) - (45 - 5) gets upright tuning
for a 31 t0 31.5 MHZ tuning range. Mixed with 6 x 67.333 gets 435 to
435.5 MHz. Its easier to switch the 40 Mhz crystals than the 67 MHz
crystals. So in these round numbers there'd be 45, 45.5, 46, and 46.5 or
67.333 and 67.417, 67.5, and 67.583. or maybe a split of switching, 45
and 45.5 and 67.333 and 67.5. Though I'd have preferred to not switch
the 67 MHz crystal because switching adds instability.
To get down to 432, the 67.333 might go down to 66.8333.
That's how I might have designed, I don't know how the 2510 was designed
or how it might be modified.
73, Jerry, K0CQ
On 4/7/2011 10:12 AM, Bill W1PA wrote:
> Jerry,
>
> I took a quick look, and most of the crystals are in the 40 or 60Mhz range.
> It also looks like the 2510B had an accessory oscillator board slot to give
> it
> an additional range above 435... I am wondering if a custom built board
> could give
> 432 with minimal intrusion (and reversable), save for the re-tuning.
>
> Bill W1PA
>
>> I presume its certain that one of the UHF injection crystals could be
>> changed to get 432, or maybe there's an intermediate mixer and an IF
>> between 9 and 435 MHz that could be moved. Though it may be what moves or
>> the bandswitching and the UHF injection is fixed. I presume that it uses 9
>> MHz and a 5 MHz VFO to create SSB at 14 MHz then mixes up from there in one
>> or two steps. If in one, then the selectivity at 435 will be fairly tight
>> and might need retuning to use 432 and might not allow 432 and 436 without
>> retuning.
>
>
>
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