I recently acquired all the transformers (and choke) from a Heathkit Apache TX-1 Transmitter.
Specs for all transformers below.
Part #: 54-65 - Power Transformer (P: 115V; S: 600V@175mA CT w/ 2 Taps @ 240V@20mA, 6.3V@9A, 6.3V@3.5A, 5V@4A, 5V@2A)
Part #: 54-30 - Plate Transformer (P: 115V; S: 1800V@400mA CT)
Part #: 46-10 - Choke 5.5H 400mA (38 Ohms)
I can't make up my mind on what to with them. One thought was that I could make a nice variable HV tube bench supply but I would hate to waste them if I could build nice tube amp. The transformers look really nice and need to be shown off.
Another thought is to build a 845 SE amp. With the 1800V CT txfr, I could get around 1050-1150 volts on the plate and use the other 54-65 transformer to power the driver tubes.
Either way, I could build one heck of a boat anchor/space heater with these transformers. I also have the option of purchasing a matching set from the same guy I bought them from. Maybe 845 SE monoblocks? 🙂
Any ideas would be appreciated!
Specs for all transformers below.
Part #: 54-65 - Power Transformer (P: 115V; S: 600V@175mA CT w/ 2 Taps @ 240V@20mA, 6.3V@9A, 6.3V@3.5A, 5V@4A, 5V@2A)
Part #: 54-30 - Plate Transformer (P: 115V; S: 1800V@400mA CT)
Part #: 46-10 - Choke 5.5H 400mA (38 Ohms)
I can't make up my mind on what to with them. One thought was that I could make a nice variable HV tube bench supply but I would hate to waste them if I could build nice tube amp. The transformers look really nice and need to be shown off.
Another thought is to build a 845 SE amp. With the 1800V CT txfr, I could get around 1050-1150 volts on the plate and use the other 54-65 transformer to power the driver tubes.
Either way, I could build one heck of a boat anchor/space heater with these transformers. I also have the option of purchasing a matching set from the same guy I bought them from. Maybe 845 SE monoblocks? 🙂
Any ideas would be appreciated!
Just an historical note, the Apache TX-1 was the successor to the popular DX-100 with a more stable VFO and the provision for direct connection of the SB-10 sideband adapter. It's appearance had to be modeled against the RX-1 receiver which raised some design challenges. The extra voltages available from the Apache were used to power the SB-10 SSB adapter.
That 900-0-900 could feed a pair of 5R4s, which are choke I/P filtered. That would bring the B+ rail voltage down to where push/pull TT21 or 807 "finals" are possibly feasible.
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Also known as the "scratchy apache" due to it's AM modulation circuit. There have been improvements made by the amateur radio communty over the years.
Because its HV winding has limited current (compared to the filament windings) the 54-65 could only likely be used for an EL84 stereo amp. Or maybe to power everything else in an 845 or similar very high voltage amp?
Desolationx, do you (or anyone else) have the specs on Heathkit "iron"?
S.
Desolationx, do you (or anyone else) have the specs on Heathkit "iron"?
S.
Steve, my thoughts exactly. What other specs are you looking for? The only specifications I can find are in the Heathkit Power Transformer catalogue.
http://akdatabase.com/AKview/albums/userpics/10007/Heathkit%20Power%20Transformers.pdf
Schematic can be found here which shows the how the taps on each transformer are configured.
http://www.radiomanual.info/schemi/Surplus_Radioamateur/Heathkit_TX-1_Apache_user.pdf
Eli, could you elaborate on your suggestion? Based on the Apache schematic, the 5R4's are in parallel with a choke input filter which brings the B+ down to 750 V. I confirmed this with PSUD. Looks like 807's are only rated up to 600 V so further voltage drop is required.
These B+ voltages on these transformers are both too high and too low for most audio applications. That's why I immediately thought of the 845. I could possibly build Tubelabs 845 SE design. I may need another transformer for the 845 filaments though.
This RCA datasheet indicates that 807s can take 750 V. in intermittent commercial or amateur service (ICAS). The 600 V. number is for continuous commercial service (CCS). Those are radio transmitting conditions, not HIFI.
In HIFI service, if you strictly limit plate dissipation to 19 W. per tube, you should be safe. Heat, not mere volts, is the tube destroyer.
Use full pentode mode and regulate g2 B+ circa 270 V., as if you were dealing with 6L6Gs. It's your call as to what sort of NFB gets used. Tertiary cathode feedback (CFB) winding O/P "iron", along with a few dB. of global NFB, would be quite nice, but there is the expense.
In HIFI service, if you strictly limit plate dissipation to 19 W. per tube, you should be safe. Heat, not mere volts, is the tube destroyer.
Use full pentode mode and regulate g2 B+ circa 270 V., as if you were dealing with 6L6Gs. It's your call as to what sort of NFB gets used. Tertiary cathode feedback (CFB) winding O/P "iron", along with a few dB. of global NFB, would be quite nice, but there is the expense.
You might find enough advantage by using two separate 10V filament transformers to make it worth the trouble. That would allow measurement of cathode current or even cathode resistor bias if needed.
YOS,
Chris
> Apache drove a pair of 6146's
For RF.
The modulators are EL34. Has EL34 ever been used in audio?
But as-said: this product jacked-up the impedance levels to where only narrow-band coupling works.
For RF.
The modulators are EL34. Has EL34 ever been used in audio?
But as-said: this product jacked-up the impedance levels to where only narrow-band coupling works.
Thanks everyone for the replies. After much thought I think I am going to eventually build an 845 SET using Tubelab's design. My initial thoughts is to use a 2a3 to drive the 845. Not sure what to tube to use yet to drive the 2a3 though.
Using a SS rectifier on the 1800 VCT transformer, I can get around 1150 VDC on the plates with a CLC filter.
There are plenty of taps for the bias, filaments and B+ for the other tubes.
I will need another transformer to provide the voltage for the 845 filaments and B+ for the 2a3 driver tube.
I will post my initial design once I am finished drafting it up.
Using a SS rectifier on the 1800 VCT transformer, I can get around 1150 VDC on the plates with a CLC filter.
There are plenty of taps for the bias, filaments and B+ for the other tubes.
I will need another transformer to provide the voltage for the 845 filaments and B+ for the 2a3 driver tube.
I will post my initial design once I am finished drafting it up.
I would use TV damper diodes instead of SS rectifiers. Slow start, no switching noise, high output current.
I am using Heathkit HV transformer and choke pair in choke input supply for parallel PP super-6BG6GA (up-rated 807), 800 V plate voltage.
I am using Heathkit HV transformer and choke pair in choke input supply for parallel PP super-6BG6GA (up-rated 807), 800 V plate voltage.
Thanks for the recommendation. I have never heard of TV damping diodes but after a quick search it appears they are really popular with the DIY audio crowd. I found one datasheet for the 6CD3 and the inverse peak voltage is very high. The voltage drop is low too! Might just have to use them.
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