Spectra modification

This forum is for the discussions targeted at converting various models of Motorola equipment to operate in the 900MHz Amateur Band.

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RonJeremy
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Joined: Sat Oct 16, 2004 5:33 pm

Spectra modification

Post by RonJeremy »

Is it possible to modify a spectra to receive on 929 MHz ?
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kcbooboo
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Post by kcbooboo »

Assuming it's already a 900 MHz model (D27, D37, T27, T37), one resistor on the VCO, and hex-edit the programming software, program your frequencies, and you're all set.

There's info about this on http://www.repeater-builder.com in the Motorola area, Spectra section. Also http://www.batlabs.com in the model-specific area, Spectra section.

Bob M.
RonJeremy
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Spectra

Post by RonJeremy »

Yes I did check that website. It seems that the radio stops at 928 MHz. Do you think I can reach 929?
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kcbooboo
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Post by kcbooboo »

If you added a resistor to bring the VCO down to 927, try a different value to let it go to 929. The radio should normally receive 935-941, so perhaps it doesn't need the 220k resistor. Try a 330k or maybe a 470k, or try it with no resistor at all; it might go down there as-is once you've gotten the software to let you enter frequencies below 935.

Bob M.
rodell
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Post by rodell »

Chances are very good the same modification for 927 will be just fine for 929. It isn't that close (usually).

If, for reasons unknown it doesn't, I'm certain changing the resistor value will do the trick.

Rob
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John G
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Post by John G »

In my experience, the Spectra should do it with no modification at all. Having said that, I have also seen a big variation in performance outside their normal range. If memory serves, you shouldn't even have to play with the software.
RonJeremy
Posts: 188
Joined: Sat Oct 16, 2004 5:33 pm

Spectra modification

Post by RonJeremy »

I can program my 929 MHz freq with rss modification. However I got the fail 001 error (or something like that) but after resistor mod, everything works except for the audio control. I hear tones when pushing volume button but it does not affect the audio (very loud). I did not try this radio before modification so I don't know if it's due to the internal mod... :(
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