Excellent flea market buy!

[eleventeen]

No, not a '59 Bassman...nor a BF Deluxe....

Fluke 407 power supply, in nice shape. 0-550 volts, 300 ma, with 2x 6.3 volt fil outputs and bias (which unfortunately only goes to -25 vdc ) but easy enough to build some appendage to put in series and lower volts for bias---no current needed, to speak of.

From Sandia Labs---hope any radiation has died down by now!

Uses 3 qty 807 as pass elements.

Very excited about this find, cost $25, killer deal, but I have to add in the &$*(#$^ $45 parking ticket I got. Other than the 807's, which are not that hard to get, got spares of all tubes needed all 5 for $5 plus a gaggle of Fender tube shields. Kewl piece!

Hope this doesn't take out the neighborhood power turning it on. Or kill me if it needs any troubleshooting. There's huge volts in this sucker.

[eleventeen]

update: Works perfect! I was wrong about the bias...there are 2 ranges...0-25 and 0-250.

Happy!

[Ed_Chambley]

Great find.  Looks like it has been well cared for.

[DummyLoad]

now that's sweetness...

congrats... ya done good.      

550V @ 300mA can take you up to 2 x KT88 territory, should easily do 50W marshall & fender stuff.

--pete

[TubeGeek]

 

Very cool find!

[alerich]

Now that's a really useful item on a tube amp bench. Good catch.

[sluckey]

BAMA has a manual if you need one. 
http://bama.edebris.com/manuals/

Here's a schematic I stitched together from the manual at BAMA.

[eleventeen]

YOU ARE MY HERO!!!  Thanks so much, Steve! I saw & dnloaded that schem but it looked, upon first glance, to be scattered across several sheets.

I have only tested it no-load and the meter is pretty accurate, and under load I am sure it will make a decent room heater as well. Those 807's are serious items....very nice Amperex tubes, as well. I am very thankful it worked & req'd no troubleshooting...the tubes (5651/12AX7/6AQ5/6AU8) are not that easy to get to. The circuitry is VERY easy to get to, but nobody (IMO) should be chomping at the bit to diddle with a +500 volt supply just for fun.

One thing it DOES do is, sort of interesting, the B+ output undergoes WILD swings should the unit be turned on from cold while set to high volts. Now, this is with no load, just my meter = no load. If turned on and set to say +500 volts, the B+ output swings from -265 (!) to settle at 500+/- 5 volts. If turned OFF set to +500 on the output, B+ swings to maybe +620, then gradually decays to zero...not that quickly, maybe 25 seconds. Point being, this could definitely blow up parts. Though I suspect under load the swings would be damped, I haven't experimented with it. Fortunately, like all power supplies of this ilk, eg; Lambda 71 and hp 712, there is a "B+ on/off" switch.

Ergo: Turn on, allow warmup, crank B+ into your victim in gradual increments.

Thanks again, Steve!

[eleventeen]

Incidentally, one modestly interesting circuit feature of this device is that the 807 heaters (6.3 volt) are lashed up in *series* which  means if any one opens up, all of them shut down.

[jjasilli]

Great PS as it does 555VDC @ 300mA!!!  My Heathkit PS-4 is only 400VDC @ 150mA

[eleventeen]

I see these for sale on ebay, they typically go for $75-80, of course you have $50 or shipping. Two of them sold recently right in that range.

If you look on ebay, there is currently a fetish for those old rackmount Lambda supplies, which I have a soft spot for and are wonderful, but they do NOT have a bias output---much less nice binding posts...and they weigh like 70 lbs...they weigh like they are solid iron. They often use 6L6 and generally come without tubes...so you have that replacement issue, though you can use cruddy old 6L6 in them just fine.

But the Lambdas, with rare exceptions often only go up to 325 which ain't enough. A Fluke 407 is more the benchtop mode like a Lambda 71 (though a rackmt flavor is available, I think it is a 407R or something logical like that) but the tubes in the Fluke are cheapo tubes...the 2 qty 12AX7 are the most expensive tubes....you can easily get 807s for $7-8, and again, power supply output tubes need not be perfect.

Imagine retubing this puppy!



Every octal socket is a 5881/6L6. Only NINETEEN of them (and  four qty 12AX7)     





Of course I am choosing a bad example...the usual Lambdas are the C-481 (only up to 325 vdc, 5 or 6 6L6) or C-482 = up to 400 vdc, I think) and some of them use 6W6 which are cheap tubes, $5 each. The problem with those Lambdas is that the sellers typically yank out the 6L6s, whereas with an enclosed supply like the Fluke....they don't!

A Fluke 407 is IMHO a far superior piece for amp work because of the bias output, benchtop form factor, lighter and cheap pass tubes.