Batboard

Hi,

I am helping a friend out with a Saber II VHF Secure-Capable, Low Power Radio. The programming was replaced with a blank codeplug...so perhaps this is the root of the issue.

I am not really clear on how to adjust the deviation on this unit...as the Align screen is not overly clear, and, of course, I do not have a service manual.

I tried using a speaker mic on the unit as well to determine if the electret mic was bad..same result. I am seeing about 1.50 to 1.75 kHz deviation when providing a constant tone into the microphone.

I see two mod adjustments- VCO and Reference

I'm used to the MTSX series of alignment screens...so any help would be appreciated.

This is a H33QXK713 model...

Any pointers?

Bob

Bob,

You will need a service monitor to check the Saber's TX deviation.
You mention replacing a blank codeplug and that could be what has set the deviation low.

Aisde from using a service monitor to properly adjust the mic deviation, you can 'adjust' the gain using the VCO level adjustment, this will bring up the transmitted audio, there is little to adjust in the Saber RSS that will change deviation level, but mic. gain can be increased this way.

it's a crappy method actually, but it worked back then, as there was less ability to use softpots like they are used and assigned these days.

Actually, the adjustment is called: VCO Modulation in the service menu.

Make certain you properly adjust the deviation for wideband and narrowband channels..IE...15 kHz, and 12.5 kHz. as both channel spacings demand different deviation levels, with 12.5 requiring 2.5 kHz, 20 kHz requires 3 kHz and 25 kHz channel spacing uses 5.0 kHz.

you can fudge a little on mid band(3.0 kHz) and use 3.5, but no more than that.

Remember, whatever deviation you use, it's actually TWICE as wide as the 'base' deviation.

2.5 is actually 5, 5 is actually 10, and 3.0 is actually 6.

Modulation acceptance bandwidth has to be followed correctly, or you risk channel splatter and over deviation.