Batboard

In the model specific info section of Batlabs under "The Spectra" there is a 900 Mhz conversion tab.
Here it describes a mod to increase the TX deviation by putting a cap across another cap in the VCO section.
The component mentioned is from the 800 Spectra VCO schematic. The circuitry for the 900 Spectra VCO is different!
Has anyone been successful in increasing the deviation in these radios to 4 or 5 khz? Details would be appreciated.
Thanks

Randy VE3OGB

I'm of the impression that virtually all the 900 gear out there has a narrow band IF and a modulation acceptance of 2.5 KHz deviation. I suppose increasing the deviation would be possible, but that would force a change of associated receiver IF filters.

Most 900 Mhz radios are designed for 12.5 Khz spacing and 2.5 Khz deviation. There are a few exceptions namely the MCS2000 mobiles and the MTX9000 portables.
These radios allow 2.5, 4.0 and 5.0 khz deviation and 12.5, 20 and 25 khz receive.
In my case I just want to use the Spectra 900 as a transmitter. I'd like to have more deviation out of the radio for my repeater.

Randy

You might find some helpful information on repeater-builder, Motorola section, Spectra area, Miscellaneous Spectra Topics article, about halfway down the page.

Bob M.

Hi Bob

Thanks for pointing me at that page, I seem to have skipped by that.
I added the cap in the vco and managed to get about 4 Khz deviation max.
This will do for my needs. Now I have to get at a 150 watt PA that I got on Ebay.

Randy VE3OGB