Check the connections. If the glow with the meter but not without, it tells me there's a break somewhere.
Try 82k 25..50W resistor (maybe on heatshink) as 10mA dummy load.
BTW why do you use series connected -rectifier- filaments. Paralleling its very common, 2.5V 10A filament transformer need.
Oh My Lord!!! Just looking at that power supply circuit diagram gives me palpitations....
Please use a variac and a
dim-bulb tester ahead of it.
Yes I know it shows a two pronged socket but you will always use the standard three prong.
Always have someone close by just in case.Be alive to enjoy the music!
Please use a variac and a
Yes I know it shows a two pronged socket but you will always use the standard three prong.
Always have someone close by just in case.Be alive to enjoy the music!
Could the act of connecting the meter cause the tubes to emit hash and glow as a result? The datasheets do say to include RF chokes.
Is this "gap" really connected?
Use a pair of 1N4007 diodes instead of the tubes. Does that work? This isolates tube-trouble from all else (wiring error, bad transformers).
Use a pair of 1N4007 diodes instead of the tubes. Does that work? This isolates tube-trouble from all else (wiring error, bad transformers).
PRR - that is a drawing mishap. that is connect. The PT CT is connected to Ground. Also, I have inserted 2 resistors to measure voltage across the 2 resistors (see attached diagram). Both resistors measure 0V across them which implies no current as well. Still can't get any voltage from the filament transformer CT unless the DMM probe is used to touch the bayonet cap and ground, then 800 voltage is present.
FWIW, the issue we are discussing is for the output stage. I have a full wave power supply for the driver stage that is working just fine. The only shared parts between the stages is the custom filament transformer that is properly supplying Vac to all the tubes (rectifiers, input and output).
FWIW, the issue we are discussing is for the output stage. I have a full wave power supply for the driver stage that is working just fine. The only shared parts between the stages is the custom filament transformer that is properly supplying Vac to all the tubes (rectifiers, input and output).
Attachments
Is the filament transformer 5V-0-5V (minimum 5A) or 2.5V-0-2.5V (minimum 10A) type?
Is it has 3 wire or 4 wire on secondary?
Is it has 3 wire or 4 wire on secondary?
Oh no! Please don't tell me you've wired it that way in #26..
Just like Xmas lights it should be a series connection.......koda's ammendment #19
Just like Xmas lights it should be a series connection.......koda's ammendment #19
Here is how I did mine. It has been glowing for 11 months without problems. I use an Amperite 60 second NO tube relay to switch on the main power transformer. A 5V 8A filament transformer is used with the 866As in series. There is a balancing wire that evened out the filament voltage as they were off by a few 0.1V.
But that is like #1...
Though data sheet says for choke input.
Hey banpuku as a test swap out your 1600V ctr tap with something smaller and omit the 0.5uf cap
Though data sheet says for choke input.
Hey banpuku as a test swap out your 1600V ctr tap with something smaller and omit the 0.5uf cap
OK fellow DIYers. We have solved the issue. On my transformer, there are 2 secondary CTs (1 for HV and 1 for bias supply). I was connecting incorrectly to the bias secondary CT instead of the HV secondary CT.
I corrected the issue and now we get 831Vdc measured from Filament CT to Ground. Nice blue glow on the 866A.
THANK YOU very much for helping.
FYI: this is for my GM70 amp. For those of you with GM70s, what is your cathode resistor / bias Voltage and plate voltage? I was planning on 800V and 85V cathode bias.
I corrected the issue and now we get 831Vdc measured from Filament CT to Ground. Nice blue glow on the 866A.
THANK YOU very much for helping.
FYI: this is for my GM70 amp. For those of you with GM70s, what is your cathode resistor / bias Voltage and plate voltage? I was planning on 800V and 85V cathode bias.
Those are some pristine 866A. All of mine look like the dog ate breakfast inside. Mercury streaks and the like
WntrMute, I see you are running an Eimac 25T. What is your plate voltage and cathode bias resistor/voltage, if you dont mind? I was thinking of using a pair of Eimac 25Ts that I have someday.
Yes, pretty much the same. Actually, I have a pair of 3C24s as well. Not sure if they would run on 830V or is that too low.