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Hi there,
I want to solve the problem of the old 2-Lug Triax output connector on the Keithley 220.
Here my solutions:
1) Adapter
Buy the adapter Keithley 6172.
http://www.amazon.com/Keithley-2-Slot-3-Lug-Female-Adapter/dp/B00C2DV92G
about $70 it is a lazy, boring and expensive action.
2) Bild a Triax cable adapter
Yes this is would be the normal preferred one, but I have to find the old male triax 2 lag connector which is more than 70$ according to my research.
3) Repalce the connector on the unit with a modern 3 lag one
I like it, on the unit there is also a lot of space.... see picture below:
And those are the candidates on Digikey:
http://www.digikey.com/product-search/en/connectors-interconnects/coaxial-connectors-rf/1443098?k=triax%20female%20panel&stock=1
So far the only connector I found <$70 on stock is
http://www.digikey.com/product-detail/en/5219/501-1312-ND/745098
But I am concerned about the quality.... I don´t to lose all the perfection of my gear on a cheap bad quality connector.
I mean this one is so expensive $170:
http://www.digikey.com/product-detail/en/DK-621-0434-1S/A101183-ND/2486192
and there is should be a reason for that.
On top of that I am concerned to damage the graphite coating of the Keithley output cable with my iron.
What you would do?
Thanks!
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$22.35 USA here Pomona Electronics 5219
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Thanks Robrenz, so do you think the Pomona 5219 (also posted in my original post) with 22.35$ will not ruin the output quality? Sorry but I have no experience with nano/pico amp currents.
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The 5219 is Teflon insulation and the 4388 at $61.75 is PTFE and hermetic sealed for 50 PSI pressure.
The original connectors on the 220 are Teflon so there will be no difference using the 5219. Also the driven guard will basically eliminate leakage currents even if the insulation resistance was not optimum. -
Thanks Robrenz, sold.
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Work in progress:
1)
2)
3)
4)
5) Auch! Removing the stupid metal cylinder cost me a isolation damage between the guard and common (see red arrow, the guard is now exposed)
Time for heat shrink... -
Need PTFE heat shrink for there, not regular ones.
Stupidly expensive but worth it.Looked on eBay and it is around $10 for it.
http://www.ebay.com/itm/10MM-PTFE-TEFLON-HEAT-SHRINK-TUBING-TUBE-3FT-/330846934065?pt=LH_DefaultDomain_0&hash=item4d08039431
First hit -
Replace the current one 2lug triax with 3lug triax, currently only the 3lug version is preffered. I saw lot of damaged 2lug with BNC cable.
The graphite coating you will not damage, the Keithley cable on picture can be easily soldered. Just wear glowes and clean it with IPA a bake it.
As a replacement of the PTFE heatshrink you can use the reqular PTFE hose, which is available in chemical lab stores.
Keithley use it in their Triax to banana adaptor Keithley 2600-ALG-2 or 237-ALG.
Send me PM message if did not find anything suitable I have about 20 pieces of 3lug triax connector (made for HP) -
Thanks, already ordered the PTFE heat shrink.
Now the Pomona 5219 supports a 0.05" MAX PANEL THICKNESS, guess what... the Keithley 220 is .063"
.
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Milling cutter? Can you chase a thread insert into it so you do not actually need the nut. From the looks you do not have to go through the thick panel just the thinner one the socket is in.
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Milling is too dirty for me...
I see the Pomona 3580...
http://www.pomonaelectronics.com/pdf/d3580_1_01.pdf
we double the price but it seems to fit, but I don´t see the 3 lugs at 120°. Some datasheets are against the human race. -
Milling is too dirty for me...
2 lug : http://www.amazon.com/Pomona-3580-Triaxial-Receptacle-Hermetically/dp/B00CJPTX34
I see the Pomona 3580...
http://www.pomonaelectronics.com/pdf/d3580_1_01.pdf
we double the price but it seems to fit, but I don´t see the 3 lag at 120°. Some datasheets are against the human race. -
Thanks don.r... I give up. PM sent to plesa.
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Just use the 5219 and don't use the lock washer. Use Loctite 242 or similar thread locking liquid. the washer is about .013" anyhow so it will work fine.
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Very interesting those D holes (from http://emersonconnectivity.com/OA_MEDIA/catalog/tromp_t24_catalog_mil_aero.pdf):
The hole in the Keithley 1,61mm panel is 9,5x8,72 mm (D5).
So the Pomona 5219 is also too big (.453"; .190", D4) ... go figure...
This one:
http://www.mouser.com/ProductDetail/Trompeter-Emerson-Connectivity-Solutions/BJ157/?qs=sGAEpiMZZMukCeVMgJHkjFN%252byJ8Fu4C5bfdAxGAckzk%3d
http://emersonconnectivity.com/OA_MEDIA/drawings/dr-BJ157.pdf
is cool (D6 but I mean at this point I can live with that) but I don´t see the magic word Teflon, but it is 500MHZ as the Pomona. It should be not so far away, here more details:
$17.12! Beauty!
EDIT: DO NOT BUY IT. THE Trompeter-Emerson BJ157 IS TOO SMALL. -
Good job finding that it looks good
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Hello zucca,
Thanks for sharing the details on the 220 triax connector upgrade. The connector on my unit is in poor shape and I will probably have to do the same. I was hoping to get some clarification on the coaxial cable before starting.
Based on previous pictures 1 & 5 the cable that runs from the analog PCB to the triax bulkhead connector has three conducting layers. It appears that only two of these, the outer silver shield and the center conductor, is soldered to the triax connector. I do not see where the copper colored braided shield is connected to either the triax connector or the banana jacks.
Would you confirm my assumption that the copper shield is not used on the output connectors? Or have I missed something?
Cable from Analog PCB Triax Output Connector (fig 2-2 manual)
------------------------ -------------------------------
Exterior Black Insulator Chassis Common (Outer Triax Shield)
Silver Braided shield * --------> Output Common (Inner Triax Shield)
Insulation (Clear)
Copper Braided Shield
Insulation (Clear)
Silver Center Conductor -------> Output HI (Center Triax Condutor)
*note: addition wire jumper goes to black banana jack labeled "output common".
Thanks
rastro -
Hey rastro,
Yes you are correct, but since we strive for perfection let´s look at the manual page to understand better the situation (pag. 6-31 6-31 or Fig 6-9):
as you can see the the connections are
Analog PCB Cable from Analog PCB Triax Output Connector (fig 2-2 manual)
-------------- ------------------------ -------------------------------
Exterior Black Insulator Chassis Common (Outer Triax Shield)
Output Common -------> Silver Braided shield * --------> Output Common (Inner Triax Shield)
Insulation 1 (Clear)
Analog Common -------> Copper Braided Shield
Insulation 2 (Clear)
Output -------> Silver Center Conductor -------> Output HI (Center Triax Condutor)
The analog common is just the guard voltage there, so that the Copper Braided Shield is there just to protect the output conductor from any leakage.
When the unit is turned on the guard white JIO14 (4mm banana jack on the back) and that conductor are connected together with the relais K307.
My questions/observations are now:
1) Why stop the guard at the triax JIO13 and not connect that with the Inner Triax Shield? The output common could have been connected to the Outer Triax Shield. Probably safety reasons?
2) The damage I did exposes just the guard, so any leakage there is not critical. The PTFE is reasonable there for the max 100V you could have between guard and ground common.
3) Why Keithley left so much space between the end of the Silver Center Conductor and the end of the Copper Braided Shield? It is not better to protect with the guard as much as you can?
To repair my damage this is my current plan:
1) cut 7-8mm of the Silver Center Conductor
2) Use the PTFE pipe I found there (see fig 2 and 3 from my old post) to cover the damage
if my assumptions are correct I will also reduce the leakage current at the connector triax since there is less Silver Center Conductor exposed without guard (probably about .00001% improvement).
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Just a heads up, the Trompeter Emerson BJ157 previously posted by me will not fit since it is a small Triax 3 lug.
I will come back with pictures and details.
We will never give up... -
Hello zucca,
Thank you for the alert. I was going to order a BJ157 connector soon - glad I procrastinated.
I still think the Pomona 5219 is a potential candidate. It may have enough clearance without having to mill or cut any of the panels.
There seems to be a couple of different datasheets; one has a drawing and the other a photo (assuming it's of the 5219 connector).
Datasheet with photo: http://www.pomonaelectronics.com/pdf/d5219_100.pdf
Using the picture and creating a scale using the quoted "connector length dimension" to that of the picture. It would appear that there is enough threaded length to accommodate the 220 panel without modification.
Also the Pomona 5219 is priced ~$23.00 on mouser
http://www.mouser.com/Search/ProductDetail.aspx?R=5219virtualkey56520000virtualkey565-5219
Regards
rastro -
Indeed rastro, you read my mind. I am returning the BJ157 and ordering the Pomona 5219. Keep you posted!
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Movie Title:
"Triax, a standard for who? [PG13]"
Main Actor:
"Forgetaboutit Frank"
Director:
"Law Murphy"
in cooperation with:
"Incomplete Datasheet Inc."
Left side: BJ157
Right Side: 2 Lug Triax (Old Keithley 220)
The Pomona 5219 are ordered, let´s see how this movie will end. -
Hello zucca,
You have a good sense of humor. This triax replacement is really confusing. There seem to be a number of standards(?) with little clear explanation.
Regards
rastro -
Finally some good luck,
and it fits perfectly with the metal & teflon pipe used in the old connector, super!
BTW 0.050" Max Panel (see here ) thickness my ace:
we can use it up to 0.125", just 250% error who cares...
double palm in my face... U N B E L I V E A B L E !
Now it is time to file the mounting hole....
and get the job done... -
Here the stencil, happy filing! Make sure to prinit it 1:1 to paper without any "fit to page" or similar settings active.
EDIT: PLEASE BE AWARE THIS IS THE SUGGESTED MOUNTING HOLE PATTERN FROM THE POMONA 5219 DATASHEET, ACCORDING TO MY EMPIRICAL MEASUREMENTS THIS IS WAY TOO BIG! DO NOT TRUST THE DATASHEET!