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GTX not TX 907-909
Posted: Wed Apr 11, 2007 4:56 am
by w2rac
Has anyone else had an problem with a M11W GTX not TX between 907-909?
Richard W2RAC
Posted: Wed Apr 11, 2007 8:56 am
by W6JK
No problem, they just don't work there. 25 MHz splits only on the 902 MHz GTXs.
Jeff
Re: GTX not TX 907-909
Posted: Wed May 30, 2007 1:16 pm
by AEC
From the service manual for the portables, the mobiles should also be similar as to frequency ranges.
Here's the data:
Receiver: 935-941 Mhz.
Transmitter: 896-902 Mhz, and 935-941 Mhz.
Receiver bandwidth: 6 Mhz.
RSS: RVN4150B (mobile/portable)
Due to the separate VCOs in both models, there is a limited(finite) range in which the radios will operate satisfactorily.
Unfortunately for the amateur community, this means giving up a wide tunable range as you normally get with UHF or VHF gear.
The second limiting factor with the GTX mobiles as a receiver, is of course, those narrow-tuned ceramic filters, and a narrow-tuned VCO, but I do believe it is possible to use the mobiles as a receiver once the filters are replaced or bypassed(not a good choice), and fiddling with the VCO steering voltage as well.
Removal of the filters is not difficult, but you MUST limit the heat used, and localize it to the filters only, or parts delamination will occur on the board...both sides!
Heat ONLY the filters, while avoiding focusing heat anywhere else if possible.
That's my take on the subject.....
Re: GTX not TX 907-909
Posted: Wed May 30, 2007 4:24 pm
by Tom in D.C.
First question is whether or not you're using an RSS in which
the .MDF file has been modified to allow transmit
slightly above
902 mHz and receive
slightly above 927 mHz. The GTX works
fine if the file is modified but otherwise you're dead. The thing
about the very narrowband FM which is standard in the radio is
not a problem with me and my friends in the DC area; the radios
work fine in stock form except for that file hack.
Have you read up on the GTX over on Model Specific Information
at
http://www.batlabs.com? If not that's a good place to start.
Regards,