HP 4338A Milliohmmeter BNC terminals

[carloscuev]

Hi, I bought this milliohmmeter very cheap from my county's ebay-like site, It didn't had its respective mating cable (HP 16143B). So I quickly ordered this chinese kelvin clips:



But it didn't worked, so I started to investigate. Turned out that the Lcur BNC is electrically isolated from anything else, with just some protection between it and ground (case). All the other BNC terminals share a common ground.



As you can see that Lcur terminal looks very weird, but there are no signs of repair or so, even in the Service Manual they state that this is correct:



Playing with it I connected Lcur ground to the other terminals ground and it worked, the question is: Anyone have this milliohmeter? Could they check coninuity of those BNCs outer shell between them? Anyone have the HP 16143B mating cable? Could you take some pictures from its insides to look what connections it has inside? Thanks.

[Jay_Diddy_B]

Hi,
I am not familiar with this milliohmmeter, but I do the 4274 and 4275 LCR meters. The wiring of the test fixture is shown here:

https://www.eevblog.com/forum/testgear/hp-4274a-lcr-meter-mini-teardown/msg399732/#msg399732

This may work for your Milliohmmeter.

Regards,

Jay_Diddy_B

[testpoint]

it is different as LCR, check here. the left BNC is empty to cable.