solid stating HV..?..

[ve6pg]

..hi from tim...somewhere, i have a drawing of the pin-outs, and diode requirements fer 5R4s, 5U4s, 5Y3s, fer solid stating a broken tube base...but, of course, i cant find it...
...so if you have the dope, please send it along....

..tnx..

..sk..

[N3DRB The Derb]

hey tim, heard you the other night on 3725 pretty well. Curious to know what TX you were on?

[WBear2GCR]

Not sure there is anything more than soldering in some silicon diodes of proper voltage (high) and current (more is better). The end of the diode with the band goes to the cathode pin of the tube base... you can put two in series for higher PIV rating, the current stays the same.

The old way of equalizing resistors and caps when using two or more diodes in series seems to be largely not needed these days, with modern silicon diodes.

Just look at your tube manual (online is ok) for the pinout.

              _-_-bear

[ve6pg]

...tnx tim...i was using a viker 2, and either the 75m dipole@50ft, or the 660ft loop...condx some nights have been great...
  ...on the tube replacement, i'll keep looking....i did have a dwg. fer this, and a list of diodes, to use....

..sk..

[WBear2GCR]

Again, all you need is the tube's pinout from the tube manual, online or hardcopy.

The band on the silicon diode goes to the Cathode connection of the tube socket, or the (octal?) base that you want to mount it into. You will likely have two diodes if it is a 5U4 style (dual diode) rectifier tube.

Then the only other thing to do is to either pick a diode with higher PIV rating than the B+ voltage and an equal or greater current rating.

If it is a 200watt class plate modulated rig, then the current for the diode is less than 1 Amp.

To get higher PIV you put two diodes together in series. So, if you had some 1N4006 diodes (I think those happen to be 600v PIV 1Amp diodes) and that was not enough breakdown (PIV) voltage you just solder two in series and then you have a 1 amp 1200v diode. Simple as that.

You can just grab an old computer monitor out of the garbage and pull the diodes, look up the numbers by putting them into Google and checking the spec sheets until you find some that come up with good numbers and the proper ratings. Then you don't have to order anything.

Or you can go to Radio Shack and probably find overpriced but usable diodes there. Mouser and DigiKey online too...

No diagram required.

If you have a specific place you want to put the solid state diodes, why not post the rig and maybe a jpeg of the spot and I am sure that someone can make some good suggestions as to what to put where, or maybe even draw up a diagram or schematic for you??

             _-_-bear

[Ed-VA3ES]

Tim, when solid-stating a  boat-anchor, I always use 1N5408 diodes. These are 1000V, 3A diodes.  Put as many in series as you need to get the target PIV.    For a 5R4,  use three in series.   You may have to use  a resistor in series to get the target voltage right.  Easily found at any electronics outlet.

[K3ZS]

The simplest way is to use K2AW rectifier blocks.    These are premade up to 14KV, have stainless steel spade lugs and bolt to the chassis.    He has ads in the back of the ham radio magazines.

[K1ZJH]

Don't forget to add the B+ voltage measured across the
first filter cap to calculate  PIV seen by the diode.
The charged capacitor voltage is additive to the peak reverse
voltage on the transformer--both are in series.

Pete K1ZJH

[WBear2GCR]

The simplest way is to use K2AW rectifier blocks.    These are premade up to 14KV, have stainless steel spade lugs and bolt to the chassis.    He has ads in the back of the ham radio magazines.

Imho, major overkill for a 200 watt class transmitter... and pricey.

               _-_-bear

[K3ZS]

The simplest way is to use K2AW rectifier blocks.    These are premade up to 14KV, have stainless steel spade lugs and bolt to the chassis.    He has ads in the back of the ham radio magazines.

Imho, major overkill for a 200 watt class transmitter... and pricey.

               _-_-bear

True, I hadn't read the post closely enough.    They are good to replace 866 or 3B28 though, in high power amps.

[N3DRB The Derb]

1N5408's are the thing for tabletop rigs. personally, I love the 3B28 - never any trouble, more forgiving of surges and weirdness than big diode strings.

[W1AEX]

Hi Tim,

When I solid stated my "Viking 3" a few decades ago I mounted the series diodes (1N4007 devices) on little perforated circuit boards and soldered them to the pins of some octal tube bases. Then I used electrical tape to mount plastic film containers as covers over the assemblies. It has worked fine business and would make it easy to repair if they ever should fail, although they show no signs of crapping out close to 30 years later.

Rob W1AEX

[k4kyv]

I have  kept the old hollow state rectifiers in my homebrew rigs.  866A's, 872A's, 3B28's, 4B32's, 5Z3's, 83's, 80's, etc.  Generally the xenon gas rectifiers are less troublesome and cantankerous than mercury ones.  The reason is that mercury is a liquid at room temperature and must be thoroughly vaporised into a gas before high voltage is applied.  Even a thin layer of liquid mercury condensed  on the inside surface of the glass envelope may be enough to cause arc-over.  Xenon is already a gas well below room temperature (boiling point −108.12 °C, −162.62 °F), so the rectifiers are much easier to start in a cold ambient temperature.

My Gates BC1-T uses commercially made solid state plug-in replacements for the 8008's (electrically the same as 872A's) and 866A's.  I solid stated the bias rectifier because I needed to liberate the 5R4 octal socket and use it for the 6AS7G DC amplifier that isolates the protective bias I added to the final PA to allow for CW mode.  I don't remember the diode number, but as I recall it has higher than usual PIV, and I'll have to look to see if I used just one diode per leg, or two in series.  No problem after at least 5 years.

I never had much luck making HV rectifiers out of a series string of diodes with equalising resistors and capacitors.  Eventually, mine inevitably went off like a string of firecrackers, no matter how many I used or how carefully I chose components for the circuit.

[ke7trp]

I agree with Don. I try to get the Plug in solid state rectifiers.  I have had 5408s last but anything less tends to go.  Even the plug in PWD 5R4 I had did not last a year.. One day the thing blasted.  Probably an arc over or something.  All the big plug ins always work.

I like the 3B38s also..  I see no difference in performance from 3B28s to the solid state plugs ins.

Clark