Sequence For Powering Up HB Rig?

[W9ZSL]

Hello again!  I'm ready to start the build on George.  Last time I posted, my plate iron for the 4-125A had a 230 volt primary and I wondered about how to divide that with the 120 VAC iron used elsewhere.  It was from the Gates BC-1T-250 before the xmtr was converted to a KW.  That problem is now N/A because I scored a NOS Thordarson plate xfmr with dual 115 volt primaries so I can actually run high and low power!    I'll be running 1800 VDC high @ 300 ma. for the final and 1250 for the modulator with a matching Thordarson.  Done deal.  Now everything in the rig can be happy with 120 VAC.  This is going to be super cool!  I'll be listing the 230 volt iron shortly as it is now surplus.

Here's the question.  I have solid-state substitute rectifiers salvaged from the Gates BC-1T so when I hit the plate switches, there it is...one for the RF and the other for the modulator.  Again, problem solved.  However here's the rub.  Can the filament switch for the 4-125A also switch on a solid-state bias supply and a screen supply provided the screen supply is rectified by a tube?  I have a delay relay that can be used for the screen supply if necessary.  Of course the filaments go on first then the plate.  SOP no-brainer there!  

Mike
W9ZSL

[WA1GFZ]

Don't apply screen voltage without plate voltage.
Heaters
bias
Plate & screen.
Screen can come up after plate

[W9ZSL]

Good enough.  All I have to do is tie the primary of the plate and screen supplies together.  Bias would come on with the fils then plate voltage with the screen coming up as the 5U4 or 5Y3 fires up and conducts.  Thanks!!!

[KA2DZT]

Just what is George going to be??  What tubes modulated by what tubes?  Two plate supplies or just one?  Can you let us know.

Your design should protect the screens from having voltage without plate voltage.  Even for just a few seconds the screens can be damaged if there is screen voltage without plate voltage.

Fred

[W9ZSL]

Hi Fred!  This was a running topic a few weeks ago.  "George" has been in the planning stage for about 12 years.  There will be separate supplies for the plates of the RF PA (4-125A) and modulator (811A P/P). PA plate voltage will be about 1800 under load at a max of 250 ma.  I'm shooting for about 275 to 300 watts input.  The modulator will be close to 1250.  The plate irons are matched Thordarsons rated at 300 ma each.  The mod iron is a Hammond 175 watt NOS job.  I salvaged a Gates BC-1T years ago.  Unfortunately the plate iron was shorted on the sec.  However I still have some parts left over that will be going into this build including a time delay relay which can be used for the screen supply if needed.  That supply could be switched on along with the PA HV and since the HV will use a solid-state rectifier (equivalent to 8008s) from the Gates, a conventional supply with a 5Y3 or 5U4 will bring the screen voltage up to full only as fast as the rectifier heaters allow.  Thanks!  Mike-W9ZSL