MV rectifiers in the CT for looks, when all else fails

[Opcom]

Many people like the appearance of mercury vapor rectifiers, especially the blue glow of them. They look really cool when the transmitter is being modulated, and even in an amplifier where the current change is not as dramatic they look good.

MV rectifiers are not always available in the sizes or rating people want, or it might be inconvenient to use them because of the filament transformer insulation requirements, etc.

For appearance sake, a couple of MV rectifiers could be put in the plate transformers center tap to GND. They conduct at 15V so there is no real issue..  And the rectifiers could be chosen for the best 'looks' like a larger unshielded glowing space between anode and filament. It would also be easy to filter the hash (if any), and everything there is low voltage. In this way, it may be possible to have the desired appearance without disrupting anything and also one would not have to worry about the rectifier voltage ratings, only current.


Another idea, not very good, is to use something other than a mercury vapor rectifier to get the 'glow'. It's more toward the creative aspect than function at that point. When I was in my teens I put a couple of small "germicidal discharge lamps" in series with the plates of a 100W P.A. amp. It didn't seem to harm anything but the voltage drop was a little high, maybe 100V. Once the 600V B+ came up and they lit, it didn't seem to cause audio issues. Those lamps were clear mercury vapor types. I mounted them behind an acrylic window and they'd glow, and be somewhat modulated by the amp's output. My musician friends liked it anyway because the amp would glow from within and freak people out. This would not be suitable for ham radio stuff though, it would be like putting disco lights on the transmitter.

[N0WEK]

"it would be like putting disco lights on the transmitter."

You say that like it's a bad thing! 

[Ed/KB1HYS]

I like them so much I HB'd a Full wave bridge rectifier, FOUR 866's.   If I rebuild it, I will put them all four in a row up front, now I have them 2x2 which looks Ok, but I think the row with a 'heat shield' behind them would be the cats meow.

I should have grabbed those 8008's when I had the chance...

[Opcom]

"it would be like putting disco lights on the transmitter."

You say that like it's a bad thing! 

I guess it depends! Fluorescent lamps come in various colors too. There are also those strange 'RF excited lamps' made for 'rife' than one could order made with just about any gas. I guess Argon would be a good partial fill since it has a low ionization voltage. I wouldn't take it that far, I'll stick to MV tubes for "modulation indicators". But for lighting the inside of the RF enclosure or other visible spaces, I'm not above doing something creative.

No one ever did say if they thought MV rectifiers could be operated in series. e.g. a FWCT with two 575A's in each leg.

[Bill, KD0HG]

For all the above reasons, my 304 rig uses a pair of 8008 MV rectifiers behind a glass window.

Not mentioned- I'm thinking you can get a nice summer tan in mid-winter from that ultraviolet glow...

Bill

[Ed/KB1HYS]

I saw a "Radiation Warning" label on some equipment with MV rectifiers (866) once.  I wondered if they meant UV?  I doubt they could emit any x-rays, could they?

The fella with the "Cool Rig" built on the fridge had whipped up some neat looking MV simulations using blue LED's, jars and creative metal work. 

[Opcom]

It is written that anything over 16KV can cause x-rays.

It is possible some very tiny amount of radioactive gas was added to the rectifiers, which is harmless.

The fridge guy could have used more (or some) UV LEDs, to get closer to the 'proper' MV color. I can appreciate the work put into the project but I was not really impressed by it enough that I would have it operating and flashing those lights at my little station. That's the sort of thing I meant by "disco lights". I don't intend to be cruel about someone else's artwork but I really did not like it.