Based on your "good audio" report of this board, I'd say it's probably out of an old paging link repeater station, which used a flat audio version of the audio&squelch card. Next, based on your comment of an abnormally long squelch tail, it may have been out of a low or mid band base/repeater. I've used some old A&S boards out of old Micor mid-band repeaters, and had the same results - nicer audio response than a standard vhf/uhf 6006/6007 station board, but long squelch closure. You can do two things - either change out a few caps and resistors in the squelch circuit area to convert the low/mid band version to a vhf/uhf version (by looking at the schematics to see which components differ), or even easier, take an original 6006/7 board and change a cap or resistor in the first preamp stage to match the frequency response of this 8406 board.
I forget the exact part number or location (I'm at work and my notes are home), but if I recall correctly, there's a 0.0056uf cap in the feedback circuit on the preamp in the standard boards. IIRC, its right next to the other cap that is either in line or disconnected based on the jumper used when no pl filter board is present. In the flat audio boards, this is replaced with a 15k or so resistor. I've found that by adding a 12-15k resistor in series with the 0.0056uf cap give an almost perfect audio response when run thru a repeater controller set for standard audio. Matched with the frequency curve of the Micor exciter, the repeat audio is almost identical to the input audio. Eric KE2D --- In [email protected], [EMAIL PROTECTED] wrote: > > Hi All, > > Here's another question. I opened up a VHF RT Station and did not find the > '4310 or '6006 audio board. What I found was a TRN 8406 a3?? Also on the > same board was stamped 22004 also on the PC board is 84D84214L02 and lastly > 1-03-02. > > Anyway, this board has the normal PL board and Vibersponder, and the > cleanest audio I've heard, but on hell of a squelch tail! A Moto radio/ht with > reverse burst is 100% no tail, but any jap-trac (we must be politically correct > ... non-reverse burst radio) leaves on heck of a tail regardless of distance > or signal strength. > > I do not have any low band or 800/900 manual around. Any Ideas? > > 73, Brian, WD9HSY >
