Did you calculate the correct LO frequency? Also you may try reversing the high byte and low byte figures of the receive frequency.
On 11/21/07, John Barrett <[EMAIL PROTECTED]> wrote: > > This one is for folks that know the Kenwood TKR-820 repeater J Or how to > modify a VCO frequency range J > > > > I have a known working on 451.125/456.125 TKR-820 UHF repeater that I'm > attempting to move down to 441.350/446.350… I've got the chip reprogrammed > and the transmit VCO had no problems retuning to the target frequency ( > 441.350). The receive VCO is another story… The manual says that PLL/VCO > lock happens when the voltage from the PLL's integrator is between 4 and 5 > volts, with a target of 4.5 volts. After adjusting the VCO's variable > capacitor (the only adjustment available), the best I can get is 2.5volts, > and I'm getting a slow sawtooth on the integrator output from the > PLL. This is surprising to me since it seems the RX and TX use identical PLL > and VCO modules, and the RX VCO only has to tune down to 446.350… 5mhz > higher than the TX. In any case.. the 2.5v control voltage is obviously > incorrect since I cannot key the repeater with my HT at that adjustment. > > > > I have pulled the CTCSS configuration chip as recommended in one set of > retuning instructions so I should be able to key the repeater without a PL > (the repeater controller will be handling that in any case, so that chip > will likely never be reinstalled). > > > > Any ideas what I might be doing wrong, or any tricks on how to get > everything tuned up ?? > >
