mv diodes can blow back, when very hot and under high voltage & load. /transmitters/
my stax amp is low current device, not crossing any max ratings on tubes.
Still have some tube gear to deal with from time to time... Built a 50 wpc amp using p-p 7027A's a long time ago and used two 816 m-v rectifiers on the 450 v HT supply; used a 6NO31 amperite 30 second time delay tube to delay application of HT to the m-v tubes. (Caution, the higher power m-v tubes require 2 to 5 minutes pre-heat!)
Suggest using a choke input (L-C) filter with m-v tubes. May save you some arc back trouble even with the 83. I never liked the 83 unless there was delay applying HV. The filament would not vaporize the mercury rapidly from a cold start and simultaneous application of filament and HT was trouble.
1-kw AM transmitter with parallel 833A in RF final and P-P 833 modulator used two 575A m-v rectifiers for the 2500 volt supply. The 5 kw AM transmitters were generally run off 208 v 3 phase and typically used six 8008 or 872 m-v rectifiers for a 5 kV supply and 866A type m-v rectifiers for the low voltage stuff. The 50 kW AM transmitters were run off 480 volt 3 phase line and typically six 857B m-v rectifiers produced the HT in the 9 to 16 kV range...the RCA ampliphase transmitters generally had a 16 kV HT supply for the 5671 tubes. Most of the tube gear in radio broadcast has been retired now or used for standby.
The higher power m-v rectifiers required pre-heat. The 15 v drop across the m-v rectifier was constant regardless of current; this was good for class AB audio amps with varying plate current. This was necessary with modulators in AM broadcast transmitters.
One MUST be careful not to break a m-v tube; mercury is toxic and especially the vapor if a hot tube breaks. Powdered sulfur is often used to clean up mercury messes.
About the PS drawing in #16
1. I don’t see how the 83 rectifier can charge the 40uf cap as no CT is on the TX is shown.
2. I would connect the HOT AC on the HV TX switch to the switched filament’s TX, and then the filament’s need to be on before the HV can be applied.
3. One additional resistor in the TX CT will limit the peak current.
4. You may consider adding a HV fuse to the HV TX only.
Duke
1. I don’t see how the 83 rectifier can charge the 40uf cap as no CT is on the TX is shown.
2. I would connect the HOT AC on the HV TX switch to the switched filament’s TX, and then the filament’s need to be on before the HV can be applied.
3. One additional resistor in the TX CT will limit the peak current.
4. You may consider adding a HV fuse to the HV TX only.
Duke
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