Globe King 500 & subbing 1N2637 for 866

[Jim, W5JO]

Do you test a 1N2637 in-circuit? Can a HV SS rectifier be checked to see if it is intact using a DMM?

Put several 9 volt batteries in series and compare the input voltage to the output using your voltmeter.  As I recall the 1N2637 is close to the 866 voltage drop of 15 volts.  I believe there are 10 diodes in the stack which will come with near a 10 + volt drop.

[WB6NVH]

Going slightly off topic, there is a guy on eBay selling government surplus rectifiers, new in sealed bags, as 866 substitutes.  They don't look right in the photo but I bought a couple as they were cheap,  They are about half the height of a 1N2637 and do have a 4 pin base like the 866. But the cap is 6146 sized, not 866 sized.  There are no useful numbers on the "tube" or the packing other than an NSN.

My guess is these are probably solid state 3B24's or 816's taken out of old FAA radar parts stock.  Has anyone figured out what these really are?

When I get a spare weekend at work I will try to run the NSN through the federal system and see if there is any useful data there.

[K4RT]

Geoff, I can't answer your question but hopefully someone here will be able to.

Thanks Jim. I don't have 9 volt batteries on hand so I used an 18 VDC 200 mA wall wart, with the result that I measured approximately 12.5 VDC flowing from the pin to the anode and 0 volts in reverse on two 1N2637's. Should a higher voltage be used for testing?

[Jim, W5JO]

I used an 18 VDC 200 mA wall wart, with the result that I measured approximately 12.5 VDC flowing from the pin to the anode and 0 volts in reverse on two 1N2637's. Should a higher voltage be used for testing?

No that will work.  I have tested them with only one.  You should be good to go. 

[K4RT]

Ok Jim. Thanks for the idea. Incidentally, I have a third 1N2637 that showed the same result forward, but in reverse, I measured 0.01 VDC. I'm wondering if that might indicate defective diodes in the stack.

An unrelated question comes to mind. I'm curious to know if any Globe King owners are regularly using their transmitter on CW. I have yet to do that.

[Opcom]

I was going to save this till April:

The ultraviolet from the glow of MV rectifiers kills virus in the shack.

Thereby, solid state is unhealthy.

73DG

Why wait until April to help your fellow hams stay healthy?  Another often ignored issue when solid-stating the supply is the corona discharge released around the tube sockets due to the increased voltage.  That and NOT controlling the virus adds up to a very dangerous combination.  Hi HI!  Long Live the 866A and 872A!  Such a beautiful and healthy glow.  What's not to love?

The voltage drop across those diodes takes care of most of that

I was going to save this till April:

The ultraviolet from the glow of MV rectifiers kills virus in the shack.

Thereby, solid state is unhealthy.

73DG

Why wait until April to help your fellow hams stay healthy?  Another often ignored issue when solid-stating the supply is the corona discharge released around the tube sockets due to the increased voltage.  That and NOT controlling the virus adds up to a very dangerous combination.  Hi HI!  Long Live the 866A and 872A!  Such a beautiful and healthy glow.  What's not to love?

-------------
That is why one should always use healthful glass in front of Healthful MV rectifiers. Sapphire (synthetic) is even better for the ultra-healthy shorter wavelengths but it cost a tiny bit more. It's for discerning builders.

Unlealthy plastic (lexan, plexiglass whatever) doesn't transmit UV well if at all.

73 opcom

[W7TFO]

Brad,

If the diode dance is getting long in the tooth, I'll gladly ship you a pair of NOS 866As gratis.

73DG

[Detroit47]

Brad,

If the diode dance is getting long in the tooth, I'll gladly ship you a pair of NOS 866As gratis.

73DG
[/]quote

"Much ado about nothing"
My regrets to William

Johnathan N8QPC

[K4RT]

Brad,

If the diode dance is getting long in the tooth, I'll gladly ship you a pair of NOS 866As gratis.

73DG

Dennis,

Thank you. I really appreciate that. I have 866's as well as 3B28's. My intent in picking up a set of 1N2637's was to have them as spares.

Brad