Out of band Astro Spectra UHF limits?

[Pj]

Looking at picking up an Astro Spectra in the 450-48x range for mostly RX use in the metro areas, but would like to use them for 440 as well. Not having a UHF AS before, how well do these typically go out of band...say down to 440 and up to say...507ish (RX)? I know milage varies...but just looking at real world operation.

[n7maq]

Looking at picking up an Astro Spectra in the 450-48x range for mostly RX use in the metro areas, but would like to use them for 440 as well. Not having a UHF AS before, how well do these typically go out of band...say down to 440 and up to say...507ish (RX)? I know milage varies...but just looking at real world operation.

Of the few (6 to 10) R3 units that I have had most of them will work analog well into the ham band, some as low as 440, but most only to 442 or so. I have never got a IMBE unit to work below 450 in digital with the R3 codeplug.

Jim

[dxon2m]

I think 507 will be a big stretch, you might be able to get up to lower 500 if you are real lucky.

[motorola_otaku]

It all depends on the VCO and RX prefilter. I have a set that will let me TX and RX from 440 to 490, but I've seen others that would go FAIL 001 on anything below 443.5, and deaf as a fencepost about 488. My suggestion would be, if you have an analog range 3 Spectra that covers the frequencies you need pull the VCO and prefilter from it and drop them in your Astro Spectra (and retune, of course).

IMBE on 440-450 from a range 3 radio is possible; it requires moving one of the test frequencies down into the ham band, or close to it. The exact hack method has not been openly posted AFAIK, but I suspect it involves reading the codeplug out of the radio as an unpacked archive and hex-editing the target frequency. There is a checksum fix needed before the radio will take it, but again, the method has not been posted. Any range 3 Astro codeplug will receive IMBE in the 440-450 range, but won't transmit because the deviation is too low.