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 Post subject: Tube adapters for the Precision 900-series
PostPosted: Aug Wed 30, 2017 1:30 am 
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Joined: May Thu 04, 2017 1:08 pm
Posts: 215
Location: Raleigh, NC area
I'm a bit confused with tube tester adapters. I've read that Precision, Eico and Coltronics adapters can be used with the Precision 912, which doesn't have 9-pin, 10-pin, or Compactron. And would it be the same for all Precision 900-series testers?

What adapters do you know of that work with the 912? I know of these--do they all work?
Coletronics B-16 -- several sockets
Precision G-140 -- several sockets
Eico 610 -- several sockets
Precision G-109 -- Noval only, and easy to make, but 912 needs a filament modification

Are there others? And, if an adapter works with one brand of tester, is it good for other testers too, since the adapters are just "wiring."

And I guess the adapters themselves came with charts(?), but what test data do you use with G-109 in the 912? 10-12 data?

Newbie questions...


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 Post subject: Re: Tube adapters for the Precision 900-series
PostPosted: Aug Wed 30, 2017 2:54 am 
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Joined: Mar Sat 14, 2009 5:56 pm
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Location: RI, 02885
There's also a Precision A-15 adapter. All have some test data with the instructions and some of the test charts include adapter settings.

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 Post subject: Re: Tube adapters for the Precision 900-series
PostPosted: Aug Wed 30, 2017 11:13 am 
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Joined: May Thu 04, 2017 1:08 pm
Posts: 215
Location: Raleigh, NC area
Ah, yes, ok...

I guess a more general question: Can these adapters usually be used with different brand/model tester than they were originally intended for (assuming you can translated the levers/buttons on the testers themselves)? I guess an example of a non-obvious one would be the Mercury AD-4?


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 Post subject: Re: Tube adapters for the Precision 900-series
PostPosted: Aug Wed 30, 2017 5:10 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 2011
Location: Oswego, NY, USA
The Precision 900-series (their charts are designated with the label "DRC") purposely did not get wired with some of the older style sockets (including the Octal socket) with the socket pin numbers wired in ascending order (A-B-C-D, etc.); instead they were wired according to the heater/filament, grids, and plate functions to correspond to certain panel Lettered switches. But, the "newer" style sockets (including the 9-pin-miniature common socket, which some of the add-on boxes listed above plug into) were usually factory wired (on the very late production 900-series testers) in ascending order to the panel switches, so no changes to make for it to work on a 900 seris. This factory socket wiring must not be altered to keep it consistent with the published DRC charts. What I am saying is to pay attention to your tester's sockets panel wiring when using an add-on box, so you will flip the correct panel switches...because the older sockets including Octal are not wired in ascending order as they are in most other testers. The 900 series circuit diagrams shown on "oldradios" site show the wiring that's supposed to be there. If one's add-on box doesn't work correctly on both Precision 900-series and your other testers; one can add a double-throw multi-pole mini-toggle switch on the box to make the conversions. I did that so one box will work on Triplett 3414/Weston981-3/Heath-TT1 and most other testers...one mini-4pole-2throw toggle sw worked.


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 Post subject: Re: Tube adapters for the Precision 900-series
PostPosted: Aug Wed 30, 2017 6:41 pm 
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Joined: May Thu 04, 2017 1:08 pm
Posts: 215
Location: Raleigh, NC area
Fred Scoles wrote:
The Precision 900-series (their charts are designated with the label "DRC") purposely did not get wired with some of the older style sockets (including the Octal socket) with the socket pin numbers wired in ascending order (A-B-C-D, etc.); instead they were wired according to the heater/filament, grids, and plate functions to correspond to certain panel Lettered switches. But, the "newer" style sockets (including the 9-pin-miniature common socket, which some of the add-on boxes listed above plug into) were usually factory wired (on the very late production 900-series testers) in ascending order to the panel switches, so no changes to make for it to work on a 900 seris. This factory socket wiring must not be altered to keep it consistent with the published DRC charts. What I am saying is to pay attention to your tester's sockets panel wiring when using an add-on box, so you will flip the correct panel switches...because the older sockets including Octal are not wired in ascending order as they are in most other testers. The 900 series circuit diagrams shown on "oldradios" site show the wiring that's supposed to be there. If one's add-on box doesn't work correctly on both Precision 900-series and your other testers; one can add a double-throw multi-pole mini-toggle switch on the box to make the conversions. I did that so one box will work on Triplett 3414/Weston981-3/Heath-TT1 and most other testers...one mini-4pole-2throw toggle sw worked.


I'm very glad you replied, Fred. I've read many of your posts, regarding the Precision testers. This is essential and valuable information which you probably wrote in the past, but didn't register with me.

As you may have surmised, I bought a 912 which does not have the factory-wired 9-pin socket (and at present I don't need it). I might just add it on the 912 panel later, but then I might also need Compactron, hence the thought to just buy an adapter box when I can find one at a good price.

So, Precision-branded adapter boxes, which plug into the Octal socket, should work properly with the 912. And I would expect them to NOT work on other branded testers. Conversely, other branded adapter boxes might NOT work on the 912, when plugged into the Octal socket, or perhaps other sockets. Is that what you are saying?


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 Post subject: Re: Tube adapters for the Precision 900-series
PostPosted: Aug Wed 30, 2017 9:29 pm 
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Joined: Mar Sat 14, 2009 5:56 pm
Posts: 4263
Location: RI, 02885
The instructions for the different adapters will include other brands and models that the adapters can be used with and have the charts. For example, the Precision G-140 will work on Precision (of course), Philco and PACO as long as you have the specific data for the compatible models. I did note that I didn't see data for the 900 series. Only the 600 series and the 10 series for Precision are in the instructions I have on hand. The instructions do include pin-out charts for the adapter so it may be possible to develop your test data. I know I wouldn't try.

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 Post subject: Re: Tube adapters for the Precision 900-series
PostPosted: Aug Wed 30, 2017 10:27 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 20036
Location: Utica, NY 13502 (USA)
I have a Precision 912 without the 9-pin socket. The roll-chart is DRC-G2A which does list many early 9-pin miniature tubes. The tester came with a Coletronics A-15 socket adapter which includes the following sockets:

12-pin Compactron socket with a "0" hole where the space should be
9-pin Novar socket
5-pin Nuvistor socket
7-pin Nuvistor socket
10-pin miniature socket with center pin (#10). 9-pin miniature tubes use this socket also
10-pin "decal" socket (no center pin), same diameter as for 9-pin miniature tubes but with 10 pins and smaller locating key space.

The tester also came with a Coletronics B-16 adapter which has all of the above sockets plus:

9-pin Magnoval socket...same spacing as Novar tubes but with larger diameter pins.
2-pin socket with empty hole between the pins. I don't know what that is used for.

Both of these adapters (A-15 and B-16) are equipped with 9-pin (miniature tube) plugs at the end of their cables. Since my tester doesn't have a 9-pin miniature tube socket, the adapters plug into a miniature-to-octal adapter with a stub for pin 9 to which tester's grid cap attaches. The Coletronics adapters also have one of these stubs.

My tester came with 3 test data update booklets specifically for the 910 - 954 series. The latest one is dated 6/1/68 and includes all of the tubes listed in the previous updates. In all cases, the stud on the octal adapter is used unless instructed to use the one on the socket adapter module. For Compactrons, they instruct you which socket pin number to place the locating key over (one pin goes into the empty "0" hole in the socket.)

Setting the tester up to test Compactrons is quite complicated but it works. I don't know if these Coletronics adapters can be used with other testers but the update booklets certainly cannot. I've found that using my 912 tester is both fun and educational.

Dave


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 Post subject: Re: Tube adapters for the Precision 900-series
PostPosted: Aug Wed 30, 2017 10:51 pm 
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Joined: May Thu 04, 2017 1:08 pm
Posts: 215
Location: Raleigh, NC area
Whew! Great info, thank you.

Thank you, Bugman. I saw that I had missed the G-140 info on the oldradios site (link farther down the page). Indeed, test data for 900-series is not given. Bummer that...

At least I can make a 9-pin adapter like the G-109.

Dave, thank you for those details. Sounds like you are all set. I'm not quite understanding one thing: your A-15 and B-16 are Coletronics-branded and are meant to use a 9-pin socket on the tester (which was apparently wired 1:1 as per your adapter--a G-109?). And you have updated test data for 910-954 series. Is that test data from Precision or from Coletronics? Did Coletronics make it specifically for use with Precision 900-series?


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 Post subject: Re: Tube adapters for the Precision 900-series
PostPosted: Aug Thu 31, 2017 3:05 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 20036
Location: Utica, NY 13502 (USA)
Comparing the model 900 with the others in the series, the 900 appears to have enough differences that could make the set-up data and procedures different from the rest. The 900 has pushbuttons labeled A-G while the others in the series are labeled A-H and J.

My set-update books are all from Coletronics. I don't know if they printed updates specifically for the model 900.

Dave


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 Post subject: Re: Tube adapters for the Precision 900-series
PostPosted: Aug Thu 31, 2017 3:35 am 
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Joined: May Thu 04, 2017 1:08 pm
Posts: 215
Location: Raleigh, NC area
Dave Doughty wrote:
Comparing the model 900 with the others in the series, the 900 appears to have enough differences that could make the set-up data and procedures different from the rest. The 900 has pushbuttons labeled A-G while the others in the series are labeled A-H and J.

My set-update books are all from Coletronics. I don't know if they printed updates specifically for the model 900.

Dave

Perhaps I've been saying "900-series" incorrectly, referring to the models here:
http://oldradios.50webs.com/precision/

Specifically, I am interested in adapters for the 912.

I keep seeing comments about being able to use the G-140 with the 912. But the G-140 manual at that site contains no test data for the 912 or other 9xx models. The 9xx "compiled test data" on that site doesn't mention the use of adapters (unless I'm missing it).
EDIT: Yes it does and I missed it: "KEY AT column refers to positioning of compactrons on G-140, A-15, and B-16 adapters"

EDIT: Example: How would one test a 12AX7 on a 912 without a built-in socket? Does the compiled test data work for using any of the three adapters (G-140, B-15, B-16)? Or do I make a G-109 equivalent and then use the compiled test data? I have a feeling I'm making this harder than it is...


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 Post subject: Re: Tube adapters for the Precision 900-series
PostPosted: Aug Thu 31, 2017 1:10 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 20036
Location: Utica, NY 13502 (USA)
For a 9-pin miniature tube, you would plug the tube into your home made adapter. No need for a multi-socket adapter module in this case.

Dave


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 Post subject: Re: Tube adapters for the Precision 900-series
PostPosted: Aug Thu 31, 2017 4:04 pm 
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Joined: May Thu 04, 2017 1:08 pm
Posts: 215
Location: Raleigh, NC area
Dave Doughty wrote:
For a 9-pin miniature tube, you would plug the tube into your home made adapter. No need for a multi-socket adapter module in this case.

Thank you. So the 8-to-9-pin is a 1:1 wiring for that adapter. And that would make sense, as Fred said the 9-pin socket which appeared on later 912's was wired per RMA, unlike the other sockets on the 912 which were wired per function.


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 Post subject: Re: Tube adapters for the Precision 900-series
PostPosted: Mar Fri 09, 2018 4:59 am 
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Joined: Jan Tue 24, 2017 1:07 am
Posts: 6
On the "later" Model 912 testers, where was the 9 pin socket located on the panel? I have obtained a well used 912 that has a nine pin socket on the left side of the panel just above the "A" switch. It is so much used that it is worn out. I have tried using a 9 pin pin straightener adapter, but even that is causing me to get inconsistent meter readings. So I think I must replace the original socket. This is going to be a problem to remove and replace because it is designed to fit the panel and I can't find a replacement made to match it. I would appreciate a confirmation that I indeed have a 912 with a factory installed 9 pin socket. And also some ideas on how best to modify or correct the faulty socket for reliable pin contact on tubes inserted into it.


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