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3706A switch card advice

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croberts
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Joined: January 21st, 2016, 6:39 pm
Country: United States

3706A switch card advice

Post by croberts » January 21st, 2016, 7:19 pm

Hi -

We are looking at purchasing a 3706A (with a matrix relay card) for a pseudo-automated bench measurement system.
The system requirements are:
- we have 6 probes, a given measurement may be across any combination of the 2/4 of the probes (depending on 2-wire or 4-wire measurement)
- i.e. probe 1 may be a force high in one measurement, a sense low in another, or not used in another
- we will be measuring opens/shorts/DC voltage, resistance, and DC current

It appears the only switch card that allows current measurements is the 3721 - is that correct?

The 3721 only has 2 channels (41/42) for current measurement - are there any cards with 6+ channels (to cover various combinations of using any of our 6 probes across the channels in any configuration)?

Or any way to easily adapt a different matrix card to support all DCV/res/DCI measurements?

Thanks
Chad

Andrea C
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Keithley Applications
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Re: 3706A switch card advice

Post by Andrea C » January 22nd, 2016, 4:15 am

Chad,

Depends if you need current pathway completion when not actively measuring the current.
The 3721 card is only one that has some dedicated current measure channels. These two channels not only route the signal to the AMP HI and AMP LO DMM inputs, but also provide a fused current completion pathway when not switched through the DMM.

In a more general case, the 3706A and the switch cards have six analog backplane relays. Backplane relay #1 is typically used to route switched signals to the internal DMM for DCV measurements, 2-wire Ohms, etc. Backplane relay #2 is used for the sense connections for 4-wire Ohms.
The connections to the backplane relays as well as connections to the DMM inputs are available on a DB15 connector on the back of 3706A.
By jumpering the AMP HI and LO inputs to one of the available backplane relays (3 thru 6), you can in theory connect any switched channel to the AMP measure terminals of the DMM.

Are you sure that a multiplexing card like the 3721 is flexible enough for the required connections to the six probes?
Be sure to also consider the 3730 or 3731 6x16 matrix cards.

Andrea

croberts
Posts: 3
Joined: January 21st, 2016, 6:39 pm
Country: United States

Re: 3706A switch card advice

Post by croberts » January 22nd, 2016, 6:28 am

Thanks for your reply Andrea.

I was looking at the 3730 actually, and think I am going to change the configuration to use:
- 2602A/B as SMU (already have this)
- 3706A (only b/c we can't find a 3706 w/out the DMM available -)
- 3730 6x16 matrix card

Two simple follow-up questions
- we can isolate the 3730 from the backplane (i.e. to use the 2602 as external source/measure) by opening all backplane relays
- i.e. opening a channel (column/row) relay on the 3730 doesn't auto-open a backplane relay, correct?
- the 3730 row - column cross-point relays allow for use of 2+ (up to 6) unique row / column selection combinations
- i.e. I can use row 1/out column 5, and row 2/out column 2 without shorting on the relay board, correct?

Should be able to fully configure all combinations we need using this configuration, although a comparable / simple 1-slot alternative to the 3706 would be nice.

Thanks!
Chad

Andrea C
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Joined: October 15th, 2010, 10:35 am
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Re: 3706A switch card advice

Post by Andrea C » January 22nd, 2016, 7:44 am

Simple follow-up questions
- we can isolate the 3730 from the backplane (i.e. to use the 2602 as external source/measure) by opening all backplane relays
- i.e. opening a channel (column/row) relay on the 3730 doesn't auto-open a backplane relay, correct?

ANS: the 96 crosspoints in the matrix are independent of the backplane relays. In fact, you'd have to explicitly open/close backplane relays. They will be open by default.
The 3730 has two DB50 connectors. Connections to the rows on one DB50; connections to columns on the other.
Alternately you could pass the rows through to the DB15 on back of 3706A via the backplane relays, but more typical use for the backplane relays and the matrix cards is for column expansion to additional cards.

- the 3730 row - column cross-point relays allow for use of 2+ (up to 6) unique row / column selection combinations
- i.e. I can use row 1/out column 5, and row 2/out column 2 without shorting on the relay board, correct?

ANS: Yes. The six rows allow for up to six pathways. A pathway could have more than one crosspoint closed: row 1/out column 5 and 6, etc.

croberts
Posts: 3
Joined: January 21st, 2016, 6:39 pm
Country: United States

Re: 3706A switch card advice

Post by croberts » January 22nd, 2016, 7:51 am

Great - many thanks for your help Andrea!

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