diytube.com

All,
I would really like to use a type 83 rectifier tube in my ST35 project...But I have a couple of questions.
First off, I am aware that using the 1/2 wave mercury vapor tubes can add some nastiness (noise) into the circuit. Can the same be said about the 83 ?
Secondly, I know that these sort of things require about 30s of warmup before a load is put on them. Any suggestions on how to go about this ? I suppose a time delay DPDT relay circuit which goes in between the anodes and the transformer would be correct ?

Thanks !
Steve

PS - I stuffed 90% of my board this evening. Awaiting the tube sockets and coupling caps

Steve -

I used and 83 in my 300B SET amp (I'm listening to it now)
I used no silicon at all in this amp, so I used an ancient
Amperite octal base time delay relay tube with a 6.3 vac
heater and another 6.3 vac DPDT relay. The amp has
a main power switch, and a plate switch. When you first
use an 83, it's good to warm it up for awhile (5 minutes)
same thing if you move it or it gets turned upside down.
Once you throw the plate switch, the Amperite relay times
for 90 seconds, then pulls the DPDT relay, which grounds the
HV centertap, and also disconnects the Amperite out of
the circuit, so it doesn't run the whole time the amp is on.

Works well for me ...

You can see it here at the bottom, left of center ...

I used an Idec GE1A adjustable time delay relay in just the manner you describe. It has an internal DPDT relay and I used one pole for each HV secondary lead. It is adjustable from .1 sec to 10 minutes, fits in an octal socket and cost me about $25.

Gents,
Thanks for all the help. While I haven't found a tube-type of delay, I did find the items Mesherm was talking about:

http://www.surplussales.com/Relays/RETimeD-2.html
The tube idea sounds interesting though...

Thanks again,
Steve

Edit: I found this page; but I have not found a reference for the specific model numbers:
http://www.vacuumtubesinc.com/relay.html

I think it's a 6NO90 or something like that ... I'll see if I can find the circuit diagram, it was simple enough. I'd go for 45 to 90 seconds, the Mercury Vapor tubes should be hot before you apply high voltage.

Antique Electronics has a huge selection of time delay relay tubes.

I found the schematic I drew for the time delay circuit in the
300B amp.



The Amperite relay closes after 90 seconds, and puts
the 6 VAC DPDT relay into a latched "self hold" and
turns on the plate voltage by grounding the center tap
of the HV transformer, at the same time, the coil of
the Amperite relay is removed from the circuit so it
cools down. If you decide to go to a 5Z3 rather than
an 83 Mercury Vapor rectifier, you can remove the
Amperite relay and jump pins 5 to 7, and retain the
standby switch and relay.

Tom,
Ok, lemme see if I have this right. Am I correct in assuming that my transformer selection (Hammond 272JX) will still have enough umph to power all of this ?

Specs:
Secondary: 300-0-300
DC mA: 250
Fil 1 VAC: 5 V@4 A ct
Fil 2 VAC: 6.3 V@8 A ct

On the unit, I would have two switches, the main one (as per the usual plan), and the additive from this. I would throw the main switch first, but at this point, only the 83 tube would be 'on'. Upon throwing the second switch, it would activate the timer tube. When the timer tube ends its cycle, it would close the relay, thus grounding out the HV tap, and therefore turning the rest of the tubes 'on'. Sound right ? Also, I am assuming the second switch would be an 'on-off' type, that once thrown would remain 'on' ?
As far as the physical hookup goes, I would just add another connector onto J1 Pins 7&8 to supply the 6.3v Fil supply.
I see in your schematic you added a red 'ready' light. Not a bad idea...

Thanks again,
Steve

Steve -

You have it right ... the minimal current drawn by the relays won't matter.
If you look on my website at the 300B amp, I used two miniature toggles switches, one "main" and one "plate" and old fashioned jeweled lens
pilot lamps ... I had # 47 6 volt bulbs, but they were too bright, so I put 12 volt bulbs in.

... tom

Ok, now I am confidant that I completely understand what's going on. I think I'll look for a DPDT switch to eliminate having two power switches. Beyond that, I think Im ready to go.
One last (ya right...) question - what is the pin count of the 6N090 tube ? I really haven't had much luck in finding information on it...

The one I used is an octal ... here is a PDF on Amperite's website ...

http://www.amperite.com/Uploads/g.PDF

If you don't want two switches, just don't put the one in my circuit in,
it will just start the timing cycle when the power comes on. No need
for a DPDT.

Bleh...See, the instant the football game comes on; my mind goes to waste. Thanks for the link BTW