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Kenwood TK-880 / TK880 information
TK880 450-490mhz model
Out of the box, the stock radio bottoms out TX/RX at 443 mhz.
The radio is capable of going down to about 436 mhz.
Here is how to do it:
Program radio for 441, 442, and 443 mhz.
At 442mhz: Radio shouldn't receive. TX should unlock PLL (radio beeps after mic keyed for about 2 seconds).
To fix: Open radio Locate two holes (pll adjustment) The bottom hole is TC109 (towards front of radio). Go 1/4 turn ccw (brings tx down to 440mhz) The lowest the TX VCO will go is 434.5. TX range will be 434.5 to 470
The Middle hole is TC106. Go 1/4 turn cw (brings rx down to 440mhz) Lowest RX VCO will go is 436.0. RX range will be 436.0 to 470
Use KPG49D programming software and set "Sensitivity" to 60 (low), 135 (medium), 200 (high) These settings control the varactor diodes in the front end preselector.
Turn the L203 and L207 slugs fully clockwise. Further adjust by feeding 400-500mhz into the antenna with a tracking generator and put a spectrum analyzer on TP2.
Other info: The top hole is VR1 (tx power) The right hole (under speaker) is L5 or L6 (discriminator?)
The 4 inductors on left (top to bottom) are: L203(top), L203(bottom), L207(top), L207(bottom)
The receiver circuit goes from antenna thru L203, thru an RF Amp transistor,
then thru L207.