I'm about to build a cable to go from my TNC (MFJ 1270) to a Yeasu
VX-1R. The diagram for this cable is as follows:

http://www.packetradio.com/!TNCables/5PD2YVX.gif

My question is this. What are the values for the capacitor and
resistor listed on this diagram?

I'd suggest 2.2k ohms for the PTT current-limiting resistor (it's
what's used in their speakermikes), and a .1 uF ceramic or filmcap for
the DC-blocking capacitor.

A word of caution re building this specific sort of cable yourself.
I've found out (the hard way) that the 4-contact 3.5 mm plug sold by
Mouser does _not_ work well with the Yaesu VX-5R. The Mouser plug has
a fairly broad metal "shoulder" at the base, and this hits the outer
(higher) rim of the rubber sealing ring around the VX-5's speakermike
jack and prevents the plug from being inserted to its full depth. As
a result, the plug doesn't make good contact with the jack and (in my
setup at least) doesn't transmit properly.

The plugs that Yaesu (and other manufacturers) use, have a narrower
metal shoulder at the base, which fits nicely into the outer rim of
the sealing ring and seats down nicely against the inner rim.
Unfortunately I haven't found a commercial retail source for these
narrow-shoulder 4-contact plugs. The only source I can suggest is to
buy a VX-5/VX-1 cloning cable and cut it in half.

I built one of the Mouser plugs into a TinyTrak adapter cable, and
wasn't able to get the VX-5 to key up properly. I tore apart the
cable, rewired it with two separate 2.5mm/3.5mm plugs, and bought the
Yaesu VX5-to-TNC adapter. This combination works quite well.

I don't know if the VX-1 has the same "narrow shoulder" plug/socket
problem as the VX-5 does, but I'd suggest checking it before you go to
a lot of effort wiring up the cable.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
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