Tube Amp Find

I used a 6L6 as a rectifier for a VERY brief moment. They sound... awful that way. Once I got the right tubes in the correct sockets again, everything was better.
Wired just the right way, it might actually make a serviceable rectifier. Probably nothing impressive, and nothing you couldn't get done at less cost using an actual rectifier though.
 
Wired just the right way, it might actually make a serviceable rectifier. Probably nothing impressive, and nothing you couldn't get done at less cost using an actual rectifier though.
Not sure what using a 6L6 as a rectifier has to do with this thread. Did I miss the turn off on the highway?
 
Not sure what using a 6L6 as a rectifier has to do with this thread. Did I miss the turn off on the highway?
Nah, my comment was completely off the map, a random synaptic misfire triggered by the earlier discussion of 6L6s and 6V6s and KT66s and the importance of having the right tube in the correct sockets... You missed that? :)
 
Completely. ;).

Next thing we'll be saying that 5881s, which are really Russian 6P3Es, but similar to 6L6s, can be substituted for KT66s. Actually, a pair of Russian 5881s would work, and cost much less than $70. But in the power tube sockets, not the rectifier one.
 
Why stop there? ;) Various other tubes could be used, particularly if you're willing to change the tube base and/or wiring. Both 807s and 6BG6s are essentially 6L6s with plate caps on top; the 807 has a 5-pin base, while the 6BG6 has an octal base (if you're able to supply 12.6V filament voltage and have the correct 7-pin bases handy, there's also the 1625). Along with the 5881, other 'industrial' versions of the 6L6GC include the 7581/A and, with a different pinout, the 7027/A. As far as European versions go, along with the KT66, there's also the EL37. And of course, there's the metal 1614 and 1622, both of which are apparently uprated versions of the original 6L6. I'm sure I'm forgetting at least a few different possibilities.......... :idea:
-Adam
 
For the sake of the OP, Rossm. We want him to get his amp up and running without having to rewire or replace his tube bases.
Fair 'nuff. :) Just figured I'd throw the options out there. For several years now, I've had plans to build adaptors to allow use of 807s in my ST-70, but I have yet to get around to actually building them. I also have a whole bunch of old-style ST-shaped 6L6Gs I'd like to use, but they'd probably self-destruct if plugged into the ST-70. Sometimes, it's best to just keep things simple.
-Adam
 
Use a 5AR4 rectifier (new make) instead of what you have, and wait for a replacement PT to show up. You should be able to get cheaper multi section caps, or restuff the originals for less. The schematic calls for 450V caps which are common and cheaper. Single caps of 22uF and 47uF at that voltage will work fine for restuffing those cans (two inside the original can and one below). If you don't want to restuff, go for JJ multisection caps one 20 20 20 20 and one 50 50, and add one 47uF cap below.

That looks much better
qty 3 22uf @ 450v would be about $5
http://www.mouser.com/ProductDetail...ZZMsh%2b1woXyUXj6aMhg/sQ%2brx%2b%2bwtSKVRZOs=

qty 2 47uf @ 450v would be about $5
http://www.mouser.com/ProductDetail...EpiMZZMsh%2b1woXyUXj6aMhg/sQ%2brxJwiYfP/mmx0=

Thats about $60 savings.

The mouser site lists the cap voltages as AC or DC, I am thinking that I want DC ?
Also reading about lots of problems with the factory power transformer, should I get something different ? I have read the Stancor PC8412 is a good replacement
thanks
 
HI
The Power Transformer is labeled UTC R4, I checked it with my ohm meter and got the following
Primary 3.2 ohm
Sec .4 ohm
Sec .4 ohm
Sec 156 ohm

Out Put Transformer
input 95 ohm
Ground -> 4 ohm lug = 1 ohm
Ground -> 8 ohm lug = 1.2 ohm
Ground -> 18 ohm lug = 1.7 ohm

Filter Choke 162 ohms
At least nothing is shorted or open

I see now on the SM that KT66 is the correct tube, You think someone not knowing any better thought that any tube labeled with 2 sixes would work ?
Do you think the Power Transformer is correct for this amp ? I see the Heathkit part number is 54-32
Thanks for any help, This is my first adventure into tube land.....

EDIT
After more research I now know that this transformer is not correct, Bummed out now...Any suggestions for replacement ?

EDIT #2
After more research it looks like the pinout of kt66 and 6v6 are the same. Just looks like the KT66 is a more powerful tube more current flow and higher voltages. If my Power Transformer is working correctly then I should just be able to get new tubes.

EDIT #3
Not knowing what other mods may have been done it might be prudent to disassemble the entire amp and put it back together, I was planning on replacing all resistors anyway might cost another $11.

Any thoughts out there ???

I just stumbled on some specs for the power transformer on the heathkit Yahoo group, If you don't need the info, maybe the next person might

HEATH W4-AM POWER XFMR P/N 54-29, REWOUND IN ORIGINAL CASE
CORE) EI-150 X 1.5" 29GA M6X STYLE #) 04 E-I LAMINATED CORE
PR) 120 VAC 60 HZ 1 PH
S1) 760 VCT @ 130MA CCS
S2) 5.0 VAC @ 3A CCS
S3) 6.3 VCT @ 4A CCS
DM) HT = 0.000 WT = 3.750 DT = 3.390 MD = 2.500 MW = 3.000 WEIGHT) 8 LBS

HEATH W5M POWER P/N 54-32 P/N 54-32, REWOUND IN ORIGINAL CASE
CORE) EI-150 X 2" 29GA M6X STYLE #) 04 E-I LAMINATED CORE
PR) 117 VAC 60 HZ 1 PH
S1) 900 VCT @ 140MA CCS
S2) 5.0 VAC @ 3A CCS
S3) 6.3 VCT @ 4A CCS
DM) HT = 0.000 WT = 3.750 DT = 3.890 MD = 3.000 MW = 3.000 WEIGHT) 10 LBS
 
For whatever it may be worth, I saw one of these trafos for sale in BT. Not mine, no affil, etc.
 
I just stumbled on some specs for the power transformer on the heathkit Yahoo group, If you don't need the info, maybe the next person might

HEATH W4-AM POWER XFMR P/N 54-29, REWOUND IN ORIGINAL CASE
CORE) EI-150 X 1.5" 29GA M6X STYLE #) 04 E-I LAMINATED CORE
PR) 120 VAC 60 HZ 1 PH
S1) 760 VCT @ 130MA CCS
S2) 5.0 VAC @ 3A CCS
S3) 6.3 VCT @ 4A CCS
DM) HT = 0.000 WT = 3.750 DT = 3.390 MD = 2.500 MW = 3.000 WEIGHT) 8 LBS

HEATH W5M POWER P/N 54-32 P/N 54-32, REWOUND IN ORIGINAL CASE
CORE) EI-150 X 2" 29GA M6X STYLE #) 04 E-I LAMINATED CORE
PR) 117 VAC 60 HZ 1 PH
S1) 900 VCT @ 140MA CCS
S2) 5.0 VAC @ 3A CCS
S3) 6.3 VCT @ 4A CCS
DM) HT = 0.000 WT = 3.750 DT = 3.890 MD = 3.000 MW = 3.000 WEIGHT) 10 LBS

Good info.

The UTC R-13 on the OPs has a 425-0-425 @ 200mA rating. The Heathkit recommend Stancor 8412 had a 400-0-400 @ 200mA rating.
 
Sounds like an added resistor to knock down the voltage a smidge would make it work.

Given that the voltages would actually be slightly higher than stock, the fact those 6V6's didn't melt down immediately is impressive. They have to be an easy 100v above where they are rated for, and probably closer to 150v over.
 
I know, see post #12. The UTC R-13 & Stancor 8412 are suitable replacements for the original W-5M transformer. The R-4 shouldn't be anywhere near the amp.
Ok thanks, I will keep my eyes open. Do you think I should steer clear of an original w-5m transformer, do too the failures ?
 
Ok thanks, I will keep my eyes open. Do you think I should steer clear of an original w-5m transformer, do too the failures ?

Someone will chime in but I believe there may be 2 versions of that PT with one being the better of the 2. If not, avoid the original and look for a higher current, same voltage sub like the UTC R-13 or Stancor 8412.
 
Can you say why? Not enough current?

I don't know if the original PT is just a bad design or the amp @ peak draw is just too much for it.

Not knowing that I'd default too one with a higher rating than stock (~140mA) vs. lower. The UTC R-4 is ~120mA.
 
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