Great score then...better investment than a 401K

So whats next? A SSB adapter?

Carl

Here are some pix.

https://www.facebook.com/media/set/?set ... 6511cf894c

VERY nice...BUT:

You might need to replace at least a few of those glass/metal paper caps, a bathtub cap and some carbon resistors. Also that kluge of electrolytics on the PS chassis can now be replaced by exact replicas of the original cans (not available in 96) after you find some octal sockets.

Finsh up the little details and it will be a museum piece.

Carl

Will do in time Carl. Right now i have the diode load into a 70's technics amp running through the tower speakers.
Didn't know SW sounded this good. Really nice jazz coming through on 9635.

P.S. Why is it that nearly ALL 12AU7's that come in gear I buy are nearly dead? Are these tubes taxed more heavily than the rest?
I've had hammarlunds, heathkits, amps etc, and now this with weak ones.

Some testers give low readings with that tube and 12AX7's.

Carl

Anyone know why there would be a tube labeled 3223 5811 in the V 602 (5814A) socket? I tested it as a 12au7. One half tests ok, the other half isn't good or bad (sylvania type 140 tester).
What is this 3223/5811 tube? A misread/pick?

First 3223 just means it is a Tung Sol tube. Having said that I can't find the 5811 directly, but I did find reference to someone saying that the 5811 is basically a 5687. So then I looked up 5687 and compared with a 12AU7...

5687 http://tdsl.duncanamps.com/show.php?des=5687

12AU7 http://tdsl.duncanamps.com/show.php?des=12AU7

Comparing these you would see that pin outs for one of the triodes matches a 12AU7, but the other half do not (explains no test results on half the tube). Note also the filament center tap is different and the 5687 pulls 3 times the filament current. I went no further in the comparison.

Oh, and a 5814 apparently is equivalent to a 12AU7 (probably MIL screened or ruggidized in some way).

5814 http://tdsl.duncanamps.com/show.php?des=5814

Curtis Eickerman

I wonder if this 5811 tube is there because of a mod of some sort. The radio DOES play. I haven't tried the hookup points at the rear of the set, only the headphone jack, and the diode load. The radio came with a diode load cable with an RCA jack at one end, and a resistor/cap combo at the other. Diode load --> 8uF@150V cap --> 4.7k resistor --> RCA connected to splitter to home stereo receiver --> nirvana.

Are you sure that it isn't a 5814 where the "4" is partially erased?

Tony

I looked, and then got out the optivisor out and looked again. It's a 5811. The last one is SLIGHTLY shorter than the one next to it, but too long to be a partial 4.
I might have a 12AU7 lying around, but I doubt it. I've been scrounging them out of unused transceivers and other things to use.

I have looked everywhere and there is NO reference to a 5811 on any "official" document that I can find. Price lists, Hickok roll charts for a number of testers, online tube databases. No such thing as far as I can tell. I think it is a 5814 with a defective marking. If you can see the wiring into the pins at the bottom, you can often make out the connections.

Tony

Tony, they may not be in any of the official documents but tubes marked 5811 apparently do exist.

http://www.worthpoint.com/worthopedia/m ... -149008156

The poster of this information insists that they are really 5687s. Based on the fact that half of the tube doesn't test when checked as a 12AU7 I don't think it is a mis-marked 5814.

You could hook the filament pins to a power supply with an amp meter and if it pulls 0.9 A it is not a 5814.

Curtis Eickerman

Hmmm.... I'm going to go with a hunch that this is a tung sol tube (thanks Curtis!), with a date code of 5811 (11th week of 1958)

There are no other makings on it.

Could be the 5687 you mentioned, or could be a 12AU7 with a dead half.

So far there's one tube I haven't tested. It looks like I'll have to dismantle the RF deck to even remove the tube shield. It can wait.

Curtis,

Hmm. Looks to me like he is saying that 5811 is the date code (nov of 58), not the tube type. maybe thats what we have here as well.

Tony

The one on the left has the exact etchings as the one that's in the radio.

Yes. Date code. 11th week is probably right. I can never remember the date code format for sure.

Tony

Maybe so. Perhaps the actual tube number is missing from this one as well. The question becomes, which tube type is really supposed to be in this particular radio. 5814/12AU7 or a 5687. And what is really plugged into it.

If it is the wrong tube in the radio there has to be some function supported by the "other" triode that doesn't work (the triode that is pinned-out differently).

Curtis Eickerman

Well. I just plugged in a 12AU7A with no ill effects. The socket calls for a 5814A (so far as I can tell, a more rugged 12AU7). I sure hope there won't be any rumbles from shells nearby to actually NEED a shock resistant tube.

This is a beast of a set. First time I've ever had to think about what goes into lifting one for checks/repairs.

One thing to keep in mind while playing with the tubes is that the Miltronix treatment undoubtedly includes selecting tubes for the best noise characteristics. This probably doesn't apply to the 5814A in this case but in the RF and IF signal chains, the good guys cherry pick the tubes for lowest overall noise. It isn't always true that a tube that reads better on the tester is actually better in the radio. I don't know what equipment you have available, but I would do a sensitivity check on all bands before I started messing too much with the tubes.

The R-392 comes with a couple of tube pullers that can reach down into tight places and yank a 7 or 9 pin miniature tube. These are handy for hard to reach tubes like the one in the RF deck. They show up on eBay from time to time. They look like little wire baskets.

Tony

Noted, Tony. I hear what you're saying about the selected tubes. This receiver was apparently very well taken care of to look as it does 15 years after the Miltronix treatment. So that makes me ask. Was it carefully used? Left on a frequency 24/7 for 15 years? Or just looked at, and dusted off every now and then? I plan on doing the sensitivity checks here soon. As soon as I can bring myself to bring it down to the basement, negotiate around the piles of stuff, knowing that I have to bring it back upstairs.

It MIGHT be easier to bring the test equipment to IT!

As it is now, the honeymoon ain't over yet.

I emailed Rick Mish about the set, to ask him if he kept logs on the sets he sells/services to try and get some history/records of it.
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