....
(subj: Need Source for Diode in TS-1285/URM-120 Wattmeter 2-30 MHz Plug-in
Sensor)

Hi, all concerned:

The diode looks like a 1N23-type, with cathode (arrow) toward tip.

Has marking ALPHA D4190A.

TIA & 73,

Dave, N3HE

The book on mine only lists a parts assymble. From an artical in QST May
1996 it states 'it looks like a 1N21 or 1N23 but something is differant. If
replaced with a 1N21 the lowest third of each scale is unusable.'
The author states that a Wetern Electric GA50649 and dated 2/59 is a usuable
replacement.
I think the diodes were selected for each specific meter.

In another artical in September 1996 they are Sierra part numbers
SS-13154-1-n where the n is a specific digit that identifies the specific
plug-in. Sierra also made a version of the watt meter. They were selected
1N21s but you need a bunch of them to select the correct one that will work
in a specific meter.

A company called Struthers also made a version of the meter.

I can not verify any of this info above but just reporting from the
articals.

I have the Struthers version and it has a knob on it for SWR. Lucked out at
a hamfest and found one still in the origional packing box that had never
been opened from the time it was calibrated in 1983. It came with 3 plug
ins for 3 to 1000 mhz and dthe manual but the book does not list the diode
by its self, just an unreconisonable asymble.