The primary impedance in reality is whatever you dump on the secondary that reflects back to the primary, whether it be 0.001 ohms or 10 Mohm. What really counts is the turns ratio. Having said that, you're correct - 5.2 ohms on the secondary will get you 5k P-P at the primary side, just as 8 ohms will get you 8k - it's all in the turns ratio.
Given all this, the 160W OPT would work well with the 10 lb power transformer and doubler circuit (700V B+) using EL34s. With 8 ohms load you would get about 8K reflected, which would be just about 100W Po at the plate. 350V on g2 would be just about right for the peak current.
One could also stack 2 of the power transformers with bridge rectifiers to make a 700V B+ that would power a 100 WPC stereo amp using the DCPP circuit and EL34s with the big OPTs.
EL156 or EL509 would give you a little more dissipation margin than EL34s... It would be a good way to get ~100 WPC out of any of the bigger sweep tubes. Bigger is relative of course...
One could also stack 2 of the power transformers with bridge rectifiers to make a 700V B+ that would power a 100 WPC stereo amp using the DCPP circuit and EL34s with the big OPTs.
EL156 or EL509 would give you a little more dissipation margin than EL34s... It would be a good way to get ~100 WPC out of any of the bigger sweep tubes. Bigger is relative of course...
Last edited:
Ah, sorry.. I read "this transformer" without looking at the details. And I even have a pair I'm actually expecting to obtain 600V from
Thinking about using them with the doubler circuit to supply 6550s and Edcor CXPP 5K/100W OPTs.Then again I have this monster Antek 8T450 that could power both channels... Hmm ~20kg of iron on one chassis...
Results of winging it without a schematic, then drawing it later...
I was trying (and succeded I think) to limit the inrush, widen the
conduction angle, block voltage doubler DC imbalance, and stop
LC circuit ringing.
Wanted to use this rediculous 10H choke I bought on impulse
without any plan. Didn't realise then that simple CLC with this
monster would ring at low frequency. So come up with this
bizarre scheme: I would put big C in the middle of the big L.
Anyways, it works, but 600ESR is obscene. Probably useless
now anything but guitar. Did I mention, at least it won't ring?
These measurements with only the 242V secondary wired.
Not yet loaded with any filaments or fixed bias. It might drop
further by the time those other loads get wired.
Also 3A fuse on the primary. I earth grounded to the copper
strap of the beast, took a propane torch to melt solder to it!
The motor runs limit and equalize how much current is drawn
per phase. They aren't for conventional storage or filter...
The diodes are 1000PIV 3A fast recovery, not MUR460.
Thats just closest diode LTSpice had to offer.
L2 & L3 don't appear to do anything significant. But they are
there, and hard to remove now. I can short across them if I
need the extra Volt or whatever. They were for power factor
correction before I got the idea to use the motor runs...
I was trying (and succeded I think) to limit the inrush, widen the
conduction angle, block voltage doubler DC imbalance, and stop
LC circuit ringing.
Wanted to use this rediculous 10H choke I bought on impulse
without any plan. Didn't realise then that simple CLC with this
monster would ring at low frequency. So come up with this
bizarre scheme: I would put big C in the middle of the big L.
Anyways, it works, but 600ESR is obscene. Probably useless
now anything but guitar. Did I mention, at least it won't ring?
These measurements with only the 242V secondary wired.
Not yet loaded with any filaments or fixed bias. It might drop
further by the time those other loads get wired.
Also 3A fuse on the primary. I earth grounded to the copper
strap of the beast, took a propane torch to melt solder to it!
The motor runs limit and equalize how much current is drawn
per phase. They aren't for conventional storage or filter...
The diodes are 1000PIV 3A fast recovery, not MUR460.
Thats just closest diode LTSpice had to offer.
L2 & L3 don't appear to do anything significant. But they are
there, and hard to remove now. I can short across them if I
need the extra Volt or whatever. They were for power factor
correction before I got the idea to use the motor runs...
Attachments
Last edited:
Ah, sorry.. I read "this transformer" without looking at the details. And I even have a pair I'm actually expecting to obtain 600V from
Then again I have this monster Antek 8T450 that could power both channels... Hmm ~20kg of iron on one chassis...
I measure 667 volts no load, so 600 sounds realistic. Same CXPP 5K/100W OPT,
plus 10H Hammond! All three lumps about the same heft. On a giant slab of wood
1.5in thick. Ugly, ugly, ugly, and not an easy lift... Lots of exposed voltages. My
6L6 are in relay sockets that threaten to melt. Its only a breadboard for tests.
Last edited:
I have two of these with the HV secondaries in series feeding a SS bridge and 220 uF caps. I get 630 volts with probably 20 mA load (red board with no tubes installed).
I am a few parts short of firing this beast up. Similar lethal construction. Two power transformers, 4 OPT's (its an experiment since the Edcor deal never happened) a red board, and a rectifier board robbed from another project that failed, all screwed to a 15 inch square piece of high grade plywood left over from my speaker building experience.
I am a few parts short of firing this beast up. Similar lethal construction. Two power transformers, 4 OPT's (its an experiment since the Edcor deal never happened) a red board, and a rectifier board robbed from another project that failed, all screwed to a 15 inch square piece of high grade plywood left over from my speaker building experience.
No, since I am working with the red board I am restricted to pentode with Schade operation, at least until I decide to really start hacking things up.
I have a large supply of "80VA guitar amp OPT's" that claim a power bandwidth of 80 Hz to 4 KHz. My experiments have shown that for 20 Hz to 20 KHz they will pass about 20 to 25 watts. At 45 Hz 40+ watts are possible. At 1KHz I have hit 200 watts without a nuclear event. The dumb blond mythbusters kid inside of me is simply going to experiment with two OPT's in parallel to see how many watts can flow given a realistic bandwidth of 45 Hz to 20 KHz.
Recent events have caused even more significant spending restrictions on my experiments for the forseeable future.
He told me when I bought 6 of them that he had plenty. He sold a few, then stopped for a while, then they reappeared at a higher price. I expect that will happen again.
Last night my amp was on for 3 hours. It was either making full power with a sine waye into a dummy load, or cranking rock music into the speakers at full volume. The transformers weren't bothered. Maybe I need to use some bigger output tubes!
Lets see, one power transformer made 25 WPC, two transformers made 100+ WPC, what happens if I hook up 3 of them!
i have a dozen of these tubes, aside from the bigger plate caps and the 3.75 amp filament rating, plate is bigger than most tv scanning tubes i have seen.....
screen voltage ratings are likewise low......class AB2 rating of 120 watts for a pair was listed as 2% distortion, isn't this enough enticement?
Yes, I looked them up when they first started showing up on the surplus market about 2 years ago. It does look like they would work just right with the power supply that I am currently using on the red board thats made from two of the transformers discussed in this thread.
In fact they would probably work great in the red board circuit, since I currently have it configured with a 150 volt screen supply and a 3300 ohm load. Two of these transformers, each with their own bridge and 470 uF cap makes 600 volts under the full load of the 125 WPC amp.
I agree that these tubes can probably be pushed a bit beyond their 50 watt ratings especially on music peaks. I am currently running 6HJ5's which cost me $4 each (I bought several). I also got about 40 35LR6's for $4 each and I have seen them make 250 watts per pair into a 2500 ohm load on 650 volts. Since I have plenty of both tubes, I can't justify purchasing the 4D32's right now.
Note, the 4D32 was used as the RF amplifier tube in some high end ham radio gear, thus it will always be in demand and the supply is finite. It will eventually become scarce. I try to use tubes that have no current demand since the supply of all cheap tubes is finite. Unfortunately the demand goes up as soon as they are mentioned here!
Sorry this is taking forever. I just got -bias and filaments and plate caps wired.
And still not settled on what voltage regulation scheme to use for screens.
But thats not really what I wanted to ask... The point is that I had 650VDC
before I connected 6BG6GA filaments. Now B+ is 675!?!??? Why it went up?
Filaments must burn some 10pounder VAs, how could this have added 25V
to the doubler circuit? Completely opposite misbehavior than I was expecting.
There is no load connected to voltage doubler B+ right now except a bleeder.
Same no load B+ situation as I was measuring before.
Filament, B+ and -bias circuits share no common grounding yet. Coupled only
magnetically. Also no grid pots yet on -bias supply, just a FWBridge and 10uF.
The shells of the transformers and choke ARE safety grounded. There is no
star ground connection for signals and power supplies yet, I meant to say....
And still not settled on what voltage regulation scheme to use for screens.
But thats not really what I wanted to ask... The point is that I had 650VDC
before I connected 6BG6GA filaments. Now B+ is 675!?!??? Why it went up?
Filaments must burn some 10pounder VAs, how could this have added 25V
to the doubler circuit? Completely opposite misbehavior than I was expecting.
There is no load connected to voltage doubler B+ right now except a bleeder.
Same no load B+ situation as I was measuring before.
Filament, B+ and -bias circuits share no common grounding yet. Coupled only
magnetically. Also no grid pots yet on -bias supply, just a FWBridge and 10uF.
The shells of the transformers and choke ARE safety grounded. There is no
star ground connection for signals and power supplies yet, I meant to say....
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.