I have acquired about 10 Sinclair UHF mobile duplexers, MR354 and MR356's. They were originally tuned for 411/419 mhz as per the plate on the device. I am trying to retune to 414/429. I am using an HP VNA to tune them. I can't understand why I struggle to get 60db of reject out of most of them and many have IL of 5-7db. In other words they are virtually unusable unless one is willing to make significant sacrifices in performance. I removed the end plate on a couple to expose the nylon bushing and the slugs. Everything inside looks normal. Question: is there a way to find out why the duplexers aren't meeting specs? tnx Mike VE7SML

I've been using this radio for years in amateur repeater service. New users have been long-winded and it failed with now transmit power output. In the site visit the external PA had failed and the power output of the TKR850 went from the aligned setting of 5 watts down to 1 watt. In high power the most I can get out is 30 watts.... any suggestions as to the failure cause?

Attached are pages that describe it. I would like a couple more. Not going to exactly be used like the original intent. Thanks Andy WJ9J

Years ago when the X9000 mobiles were being retired out and replaced with Spectra mobiles, there was a cable available to mate with the radio end of the X9000 cable and convert to a DB25 and power connector for the Spectra. Does anyone have one or two of these cables? I have a very specific application and need a couple. 73 Kevin

It's been a long time..... but for the life of me, I can't find where to set a channel to open squelch. CPS 6.12.5 Matt AL0R

Hi Guys: I am in the process of acquiring a TKR-750 version 2 repeater (S/No. 81000***). I have attempted to disable the TA audio pre-emphasis by assigning the function to AUX I/O #1 (as shown below... I have used this method several times on my 850's). When injecting ~ 300mV into the TA audio input (pin 9 of the DB-25), and grounding pin 20 (AUX I/O #1 connected to pin 7 Control Ground), we are seeing pre-emphasis on the transmitted audio (deviation increasing from 1kHz to 4kHz) over an input frequency range from 300 to 900Hz. Beyond 900Hz, the TX deviation remains fairly flat at around 4kHz to about 2900Hz AF input signal, and then starts to drop rapidly. I suspect this is the limiter clamping the deviation at 4kHz. On my 850's, I was able to get a fairly flat audio frequency response from 300Hz to around 3kHz. Does anyone know if the 750 is different, or maybe it does not support this (even though the s/w apparently allows for it)? - I recall hearing that the TA pre-emphasis could not e disabled on a version 1 repeater, but this is a version 2.0 repeater (with the confusing TKR-750-1 model on the name plate). Removing the ground from AUX I/O #1 (pin 20) has no effect; thinking that maybe AUX I/O #1 might be bad, we programmed AUX I/O #2 the same way, and still the same - pre-emphasis on the output and no difference whether the I/O line is grounded or not. Wonder if anyone has seen this before, or whether we are chasing our tail if the 750 does not support this? Thanks in advance! Ramesh, VA3UV, WA3UV

Gang, I'm looking for this specific filter, a KVG XF-107A 10.7 MHz I.F. Filter. Does anyone have one they'd be willing to part with / sell? Burt, K6OQK