The AM Forum

   I'm trying to get a home brew CW transmitter working I got at a swap years ago. The  some of the power supply diodes are open, the diode is a K200 with a 684912 code which I assume is a date code, 1968?? I've tried looking on the net without any luck. I'm curious what the vintage is of the diode, that might help me date the transmitter's build date. I'm also curious what the PIV and FWD  would be for this device.
 
   A picture of the power supply board and transmitter, thanks....      W6TOM

https://www.google.com/search?sxsrf=ALeKk00wXp9AmtdgzgawnYUaVKJkOgTNsA%3A1614863524589&source=hp&ei=pNxAYMSUIOW2ggeL3piQBg&iflsig=AINFCbYAAAAAYEDqtJoIlbKTeppJC2Bk5_J-4fU9Cj34&q=k200+diode+datasheet&oq=k200+diode&gs_lcp=Cgdnd3Mtd2l6EAEYADIFCCEQoAE6BwgjEOoCECc6BAgjECc6BQguELEDOgsILhCxAxDHARCjAjoICC4QsQMQgwE6AggAOgUIABCxAzoCCC46CAguELEDEJMCOggILhDHARCvAToICAAQsQMQgwE6BQgAEMkDOgQIABAKOgYIABAWEB46BwghEAoQoAFQpxpYp0lgiXRoAXAAeACAAX-IAb0HkgEDNi40mAEAoAEBqgEHZ3dzLXdperABCg&sclient=gws-wiz

That is a pretty transmitter! :D

73DG

I believe that K200 part number was shared among a number of different devices ... just to be sure I would remove them and put 1N4007's .... your B+ may come up some so ease into this .... recap definitely and if it is choke input be sure to have a .01 Mfd input snubber to take care of the turn off spike

From looking on the internet at similar device pictures, it's a 600V PRV / 1A diode, cross to ECG116.

The diode seems to be a Sarkes Tarzian (see logo)
http://www.one-electron.com/Archives/Semi/SarkesTarzian/SarkesTarzian.html

K200 silicon diode rated 260V RMS, 200mA.

See Radio-Electronics-1963-10, page 45. "capacitor and dielectric analyzer" project. (archive.org or world radio history sites)
https://worldradiohistory.com/Archive-Radio-Electronics/60s/1963/Radio-Electronics-1963-10.pdf

It is an early and vintage silicon rectifier, note that it is rated in AC V RMS like some vacuum rectifiers (5U4 rated so many volts RMS per plate, etc..) so 260V RMS would be 367PIV. LOL better to call it 260VAC!


sub given as 1N540 which is 280V RMS rating, 400V PIV, but 750mA which may be easier to find vintage. A metal-cased rectifier with a stud-type or 'top hat' appearance but wires instead of hardware, if you want to try to stay period as possible.

Back when I was in high school in the third year of the Radio and TV program they apprentice you out to a TV Repair shop and about half if not more the work I did was changing diodes in power supplies of TV sets. At that time, I learned about the ECG-125 and we bought them in bags of one hundred at a time. They are a 1000-volt 2.5-amp diode that works in just about every power supply.
You can swap out a lot of those diodes just by using them. In forty years of doing this stuff don’t think I have ever seen one fail, put two in series and that will double up the voltage to 2 kV.