Hello.
I have a GM300 UHF mobile, model M44GMC98C3AA, which makes it a 12.5kHz channel radio. The radio also has narrow filters at the receiver, are the equivalent wide (25kHz) filters available as components somewhere? Do I have to change the 44.625MHz filter AND the 455kHz filters, or just one of them?
Point is, that I have a bunch of GP300 handhelds which what I am planning to use the GM300, but currently the audio distorts quite a lot when receiving the wide channel configured GP300's
Thanks
Erik
GM300 UHF narrow channel spacing to wide channel spacing
Moderator: Queue Moderator
Last edited by Nand on Sun Jan 18, 2004 9:46 am, edited 1 time in total.
Hi:
Well, this issue has already been addressed
sometime back.
If your radio is a 12.5Khz Series, the
" only " way of getting rid of the Distortion
is to LOWER the TX Dev in the GP300's OR you
can replace all the Narrow Band Parts with
the Wide Band ones....Takes a little time
and monies, but it can be done.
The 12.5 Khz models limit the tx dev as well.
Rough to get anthing higher than 3.4Khz Max
with ALL the softpot values at max
This is what I posted sometime back:
Here is a Parts List of a typical 438-470
Mhz GM300 Board ( Wide vs Narrow )
C57 2113740B29 ( N ) 15pf
C57 2113740B31 ( W ) 18pf
C58 2113740B25 ( N ) 10pf
C58 2113740B27 ( W ) 12pf
C59 2113740B29 ( N ) 15pf
C59 2113740B31 ( W ) 18pf
THESE FILTERS ARE VERY IMPORTANT
FL51 9180097D04 ( N )455Khz 6F 3.94
FL51 9180097D06 ( W )455Khz 6D 4.00
FL52 9180098D04 ( N )455Khz 4F 2.40
FL52 9180098D06 ( W )455Khz 4D 2.65
R61 0611077B07 ( N ) 22K
R61 0611077B19 ( W ) 68K
R62 0611077A26 ( N ) 10
R62 0611077B09 ( W ) 27K
R163 0611077B23 ( N ) 100K
R163 0611077B17 ( W ) 56K
R165 0611077A98 ( N ) 10K
R165 0611077B03 ( W ) 15K
R301 0611077B03 ( N ) 15K
R301 0611077A82 ( W ) 2.2K
These Filters are Expensive, but have a
Impact on Receive Performance.
Y51 9180022M03 ( N ) Filter 45.1 Mhz 12.5Khz
( $53.00 User / Approx $40.00 Wholesale )
Y51 9180022M02 ( W ) Filter 45.1 Mhz 25Khz
( $26.00 User / Approx $20.00 Wholesale )
Anyhow, depending on how well you wish the
raido to work, you can either live with the
Receiver and crank the Dev to max, or you
can go the professional route.
<font size=-1>[ This Message was edited by: [email protected] on 2002-01-27 03:26 ]</font>
Well, this issue has already been addressed
sometime back.
If your radio is a 12.5Khz Series, the
" only " way of getting rid of the Distortion
is to LOWER the TX Dev in the GP300's OR you
can replace all the Narrow Band Parts with
the Wide Band ones....Takes a little time
and monies, but it can be done.
The 12.5 Khz models limit the tx dev as well.
Rough to get anthing higher than 3.4Khz Max
with ALL the softpot values at max
This is what I posted sometime back:
Here is a Parts List of a typical 438-470
Mhz GM300 Board ( Wide vs Narrow )
C57 2113740B29 ( N ) 15pf
C57 2113740B31 ( W ) 18pf
C58 2113740B25 ( N ) 10pf
C58 2113740B27 ( W ) 12pf
C59 2113740B29 ( N ) 15pf
C59 2113740B31 ( W ) 18pf
THESE FILTERS ARE VERY IMPORTANT
FL51 9180097D04 ( N )455Khz 6F 3.94
FL51 9180097D06 ( W )455Khz 6D 4.00
FL52 9180098D04 ( N )455Khz 4F 2.40
FL52 9180098D06 ( W )455Khz 4D 2.65
R61 0611077B07 ( N ) 22K
R61 0611077B19 ( W ) 68K
R62 0611077A26 ( N ) 10
R62 0611077B09 ( W ) 27K
R163 0611077B23 ( N ) 100K
R163 0611077B17 ( W ) 56K
R165 0611077A98 ( N ) 10K
R165 0611077B03 ( W ) 15K
R301 0611077B03 ( N ) 15K
R301 0611077A82 ( W ) 2.2K
These Filters are Expensive, but have a
Impact on Receive Performance.
Y51 9180022M03 ( N ) Filter 45.1 Mhz 12.5Khz
( $53.00 User / Approx $40.00 Wholesale )
Y51 9180022M02 ( W ) Filter 45.1 Mhz 25Khz
( $26.00 User / Approx $20.00 Wholesale )
Anyhow, depending on how well you wish the
raido to work, you can either live with the
Receiver and crank the Dev to max, or you
can go the professional route.
<font size=-1>[ This Message was edited by: [email protected] on 2002-01-27 03:26 ]</font>