RadioBanter - View Single Post - New owner of HP 410LR VTVM - need probes

K3HVG[_2_] · September 4th 07, 12:35 PM posted to rec.radio.amateur.boatanchors

wrote:
Hi,

Just picked up a HP 410LR cheap. It came with no cables/wires besides
the AC cord. That is, no probes. I understand to make full use of this
instrument I will need some special probes. Where can I get a set? I
plan to use it to calibrate my tape machine and to fix tube amplifiers
in general.

Thanks,
Chris

There may have been a cheap and easy way to get your VTVM working, but I
see that your application will (may) require a.c. measurements. The DC,
Ohms, and ground probes can be obtained on Ebay, etc. by buying a couple
of sets of the military general purpose probe kits. Simply cut off the
plug ends and directly connect them to your meter. Some HP 410's have
the probes entering the front panel via small holes, others use a
screw-on assembly on the lower front of the unit. I'm not familiar with
the "LR" version. The problem is the ac probe. On the 410A,B, and C,
(to include several military clones) the a.c. probe has a powered
detector (diode) inside the bullet-shaped probe housing. Although any
of the 410-series probes will interchangeably with the the above
versions, I can't speak for the "LR". If you don't need frequency
response and accuracy up to the rated 600MHz, you could use a simple
detector diode and a resistive divider. You would need to re-calibrate
the a.c function, of course. If, on the other hand, you're going to use
a scope to measure a.c. signal voltages, you would not need the special
a.c. probe.