wrote:
I have an old TPX 720 handheld radio. It was sitting for 20 + years
and the rechargable batteries were shot. They are 1.2 v nicads, 10 of
them. Before I go out and buy more, does anyone know if I can just
put regular aa cells in it to see if it works? The nicads are 12
volts total, and the dry cells would be 15. I don't want to fry the
radio.

I've used three TPX 720s over the years, panel mounted, starting in 1980
with the first one in my Libelle, in 1984 the 2nd in my ASW 20 C, and
now 13 years with the 3rd in my ASH 26 E. It's a good radio, with clear
transmission and a sensitive receiver. I've run them all directly off
the 12 volt glider battery.

To test it, you could try 9 AA batteries (about 13.5 volts) and short
the last position in the battery holder. Or, remove the batteries, then
temporarily connect a 12 volt battery to the output leads from the
battery holder. Make sure you get the polarity right.

If the radio works satisfactorily, you can put in new ni-cads to make it
portable again. If it doesn't, there are several good choices for
hand-helds these days at bargain prices compared to what the TPX 720
cost when it was new!

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org