The AM Forum

I picked up several hv solid state rectifiers at HamCom this weekend and need to know where I can find
specs on several different types.  These are all the type that are direct replacements for tubes such as the 866, etc.  I also picked up a couple of good looking 813's and managed to drop them on the concrete....history!!  Lots of stuff there....

You need to be more specific. Do the things you picked up have any designations or part numbers on them? There is at least one company out there selling solid-state replacements, http://www.webervst.com/ccap.html
The ones from the "good old days" generally started with 1N####.

Was there Saturday morning Roy, but didn't see you.  Sri I missed shaking your hand.

There are several incantations that will sub for the 866/3B28 rectifier.  The trick is finding the part number and the specs for the number.  Like Pete said, what are the part numbers??

Darn, Jim I would really have liked to have had an eyeball QSO.  I saw alot of the people I talk with and really enjoyed it.  I picked up a few other treasures also.
The number for the rectifier is ED9840.  There are a couple of those and I have to remove some paint that was spilled on the others before I can read the numbers.  Thanks for the help.

dang, I was selling CRTs for $1 and don't recall either of yall stopping by, unless I know you by sight and not call. But maybe I was away. It's not like anyone would steal a CRT off a table or anything.

I have at least 1 maybe 2 good 813's if you want them.

I found this while Googling:
Topic was Radiation Heath hazards.

Xradiation emitted by 8020 rectifiers can be completely eliminated by replacing them with ED 9840 solid state rectifiers and by reducing the high voltage to 1820 kv.

So, find out what a 8020 rectifier is, and you got a rough idea what the ED-9840 can do.

8020's have a 40000v PIV at an average current of 100ma.

I doubt whether many hams use them for anything.

Also, assuming they meant 1820V instead of 1820KV, then you wouldn't have an xray problem with any type of rectifier.

I think that you need a plate voltage of about 15KV or higher to generate xrays.

So an 8020 could generate xrays if used at it's full voltage rating.

are those the long ones (longer than an 866)? I have some similar, FAA type, I can see what the #'s are.

These?
http://cgi.ebay.com/ED9840-EDI-8115-Replacement-Solid-State-Rectifier_W0QQitemZ250275293484QQihZ015QQcategoryZ64629QQcmdZViewItem


It's a HV rectifier for radar sets. The original was for 100mA average current. It was also designed to have some voltage drop, like 100V at 100mA, so yours might have a resistor inside. Not sure how much current it would take -your solid state ones anyway. The 1820KV thing may be a mistake (a 5KW klystron running 1820KV? - well maybe at the end of the PFN away from the rectifier tubes..)

The rectifiers is a replacement for this:
http://www.tubebbs.com/tubedata/sheets/088/8/8020.pdf

So KB5MD, Roy, right?

what are you going to do with those things - the 40KV 100mA ones?

If you still need 813's to rreplace the ones that got broken, I can give you two but you would have to come by and pick them up in Dallas.

Patrick

Turns out that the 40kv ones were bad.  The others that were more suited to my use were all good, so everything worked out okay.  I'll pass on the 813's offer, (I can't get by to pick them up) maybe next year.  Thanks, even so.

I use the 866 replacement ones in all my rigs.  I have the talls and the shorts.  I have them in valiants, Champions, Globe king ect..  They work great and you dont have to worry about an 866 arc over taking out a transformer.

Clark

I ended up with some tall ones only to find they were these "8020 replacements" but with an FAA part number or NSN. They might make nice and somewhat soft limiting/clamp diodes or something since they have the built in resistance to match the 8020 characteristic of 1V/mA drop. They checked open on a digital ohm meter because they were I suppose several diodes in series.

I use sets of commercially made plug-in replacements for 8008's and 866A's in my Gates BC1-T.  They have never given me the slightest problem, after more than 5 years.  The SS 8008's came with the transmitter, and I had a set of SS 866A's pulled from a hamfest bargain.  I have never had any luck stringing a bunch of diodes together to make up a HV rectifier.  Mine always eventually go like setting off a packet of firecrackers.  I have tried running bare diodes, using equalising resistors, capacitors across each diode, etc., and they still blow up.  They must build in gobs of extra PIV or use effective transient suppressors in those commercial jobs.

For my other rigs, I still have about a couple of bushels of M.V. and xenon gas rectifier tubes of both sizes.

I did some tests on the 8020 replacements "long stick" rectifiers

They have a 66V forward drop, which is almost consistent with the 40K PIV compared to the 10KV 866 type replacements and their 10-13V drop.

I ran 300mA through one for a few seconds, the forward drop did not change significantly with current (unlike the 8020 vacuum diode they are intended to replace). I will test further using a different power supply to see what happens when they are treated like 866's, and also what happens at currents increasing to 1 amp which is the rating usually found on the 866/3B28 replacement type stick rectifiers. It might be that they will take 866 currents. If so, the extra PIV would be welcome.

It will take some time because the sticks are potted and the heat will be slow to conduct to the outside, if in fact they do get warm. They have to be rated 100mAminimum. It is more likely they are rated higher as it would make more sense to use the same diodes for manufacturing either one. I was not quite paying attention, but I think the cathode is on another pin, from the 866 type.

sorry for this late reply but it is important that I report that 300mA DC ruined the 40KV solid state rectifier under test. No joy - -100mA only for them!