Service Mods & Info
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Modifications And Updates
447/497 CPU BOARDS
01/01/07 - The Stryker SR-440HP is now powered by three IRF520 Mosfet transistors.
04/01/07 - Excessive White Noise SR-440HP, change R35 from a 0 ohm to a 3.3K ohm. This has since been changed on all production radios (SR-440HP & SR-490HP)
07/08/08 - Stryker SR-440 / 490 Dimmer Modification
07/09/08 - The most up to date SR-440HP schematic, it has many update that previous versions did not have.
07/09/08- For increased modulation on the SR-440 / 490 you can change R249 to a 47K.
07/10/08- Stryker SR-490HP Dimmer Fix
08/13/08- Fix for transmitter from hanging up on the SR-440 and causing low receive after keyed. Locate R213 on the final board, located in the output section. Add a 1.2k Ohm 1/4 resistor in parallel with R213.
09/08/08- If you're using an FC390 frequncy counter with your SR-440/490 and it scans frequencies add a 22PF across C98 to increase injection to the mixer. This works 100% of the time.
09/08/08- Loss of TX on SR-490HP radios, touch up solder connection for L-36 on the rear PA board. The connections will look fine to the eye, but touching these up usually takes care of it.
9/08/08 - Loss of
TX on SR-440HP radios, touch up solder connection for L-34 on the rear
PA Board. The connections will look fine to the eye, but touching these
up usually takes care of it.
Disclaimer: Although the greatest care has been taken while compiling these documents,
we cannot guarantee that the instructions will work on every radio presented.