900 Spectra Front End 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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thehead7
Posts: 109
Joined: Wed Oct 22, 2003 4:35 pm

900 Spectra Front End Modification

Post by thehead7 »

Okay, I've been fiddling with the spectra front-end for some time (off and on). While fiddling, I decided to try somethng. I used solid 14 AWG wire. I put the wire through the hole in the cavity and soldered it to the back of the cavity. I was only able to do this on five of the cavities (there are six). I trimmed the length to about 1/2" or so. I swept it, and it made a significant difference, but still not optimal...

The result: Rec sens at 902.6375 went from too high to measure with my sabilock 4031, to .37 uV. A litle more fine tuning and I hope to get it down to about .2 uV or so... May be a pipe dream. At least the sensitivity is now better than, say, an Icom RP1620 (which has a nasty rated sensitivity of about .5 uV @12 dB SINAD).

The sweep showed that it was pretty low at the other end of the band, which is kind of nice, as it'll prevent desense.

If someone want's pics, let me know... I'll post them in case my description is hard to understand.

Stay motivated,
Head
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n1pfc
Posts: 246
Joined: Tue Nov 12, 2002 10:55 am

Post by n1pfc »

sure, post the pics. I may be doing this myself shortly.

Kurt
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