Need location of deviation pot on VHF GM300

firevet · Post by **firevet** » Sat Jan 06, 2007 8:41 pm

Hi all,
While I wait for a manual, would someone tell me which pot is for deviation adjustment, please?

Currently it is set for about 4.2 kHz (per the IFR) but APRS wants 3.5 or so.

Thanks
Dwight

Al · Post by Al » Sat Jan 06, 2007 9:04 pm

Maximum deviation on the GM300 series is adjusted via a softpot and by using the RSS service section(F2 from the main menu). The standard procedure calls for injecting 1 Khz at 800 mv. RMS into the BNC connector on the inline box that's part of the programming/test cable(if you're using the OEM one).

firevet · Post by **firevet** » Sat Jan 06, 2007 10:20 pm

EXCELLENT!!!!
I do have the Moto RSS, RIB and BNC on the box.

Many thanks
Dwight

ve3nsv · Post by **ve3nsv** » Sun Jan 07, 2007 7:17 am

The RSS is only going to adjust the max deviation, sounds like you need to decrease the level of data coming from your APRS controller to the radio. What are you using for an APRS controller?

firevet · Post by **firevet** » Sun Jan 07, 2007 10:04 am

The data is sent to and from a PC sound card to the GM300 mic jack. The APRS device is a custom built Linux software package with DSP and other modules that I have no idea about. The author is N2YGK available at WECA dot ORG. I am going to meet with him today and we'll see if there is more to do with it on his end.

Thanks!
Dwight

ve3nsv · Post by **ve3nsv** » Sun Jan 07, 2007 12:56 pm

Can you not just adjust the master volume out from the volume properties of your computer until 3.5khz deviation is achieved. This is really no different then what somebody with an IRLP or EchoLink node would do. Turning the max deviation on the radio down is just masking the problem if you are over driving the radio in the first place.