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What do I do with this lot?

zednut

Member
2014-03-26 3:39 pm
Hi,


Please note this is not a for sale ad, though in time I will freely admit it might get to that. If I overstep please let me know, right now I need info and ideas.


So I opened another box yesterday, I've been going through a few from a large buy of various AF and RF parts some years back that I have done little with. Recently I have found a few boxes full of tube sleeves with a mix of different double triodes, pentodes and some oddballs, all regular small B7, B9 and octal stuff. Today was different. As I found with some others all the tubes in this box were wrapped in paper, one in a heavy waxed paper with padding but all the others in regular heavy brown paper. In total the box contained 7 similar tubes


1 x United 211W
1 x GE 845
1 x RCA 845
1 x United 845W of specific batch and date code
3 x United 845W of same batch and date code
3 x 4 pin jumbo bases to suit


Hmm!


The GE and single United 845 have brown deposit to the glass but all other look unused. Bases have had heater connections soldered before but not grid or plate.



I have tested all for filament and had them light up good.


Next step I need to understand what I need to do to characterize this bunch?


I don't have an 845 amp, nor do I see building one, but I would like to know that they are, or are not any good.



At that point I might have to seriously consider how I might dispose of such a clutch.


In addition to these in the same box were a pair of 5-500 tubes and I also have boxes with what look like a pair of good 4-1000A tubes. Should I be looking for transformers or building table lamps?


Thanks for any help and ideas.
 

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Those are *extremely* valuable tubes, if they are in NOS condition, and would sell for a lot even if used and test strong. Take a look on eBay but be sitting down when you do. ;-). You could buy an awful lot of table lamps for what these sell for.

The trick to getting full value for them would be to have them professionally tested. It would be worth seeking a good testing service or a kindly fellow hobbyist who could test them for you. It would be worth a couple hundred bucks just to find out exactly what condition they are in. Even if only one of them tests good, you'd get more than your investment back.
 
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Going by the photos the 845's have done a lot of hours.

That was my thought, too.
They all look pretty-near the end of their service life.
But who knows…

Very likely, pulled from another audiophile's rig, or an HAM transmitting rig … and have seen a lot of hours. The brown deposit, if I recall, is from carbon subliming from the hot-in-service anode, then depositing relatively harmlessly on the upper inside glass.

Just remember … they're hard to build around https://frank.pocnet.net/sheets/049/8/845.pdf

Just Saying,
-= GoatGuy ✓ =-
 

zednut

Member
2014-03-26 3:39 pm
A bit more info.
All of these tubes came from the same source. The guy died many years ago and all of this stuff has been in storage since then, we're talking mid to late 1980's. The guy owned a commercial radio station and was an active ham as well. He was also a heavy smoker and pretty much everything that came from that location has a coating of nicotine, even wrapped parts.



That said it is quite possible these are weak or dead tubes so before going any further I want to try and characterise them.



My plan is to use variable HT and bias supplies to determine how they compare with the published curves. I assume this is a good indication of tube quality?


I have a Hickock 752A but I know that is of no use here.