In article ,
walt wrote:
got a model # 21 - 575

anybody got the schematic ?

Odds are it's a generic power meter.... directional coupler, rectifier,
filter and meter. The fancy part is the directional coupler.

There's a schematic for a very similar design in the older ARRL Handbooks,
or you can look at this:
http://www.qsl.net/n9zia/wireless/pics/dircoup.png

Odds are the RS one uses the same meter for both strips with a switch,
to save costs.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."