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

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

HP410LR? That's a new one to me. I am aware of the 410A, 410B, and 410C,
but not the LR. The 410(A,B,C) have their DC/Ohms probes wired directly to
the instrument, and their AC probe has a vacuum tube diode in it, and plugs
in by way of a Stereo Phone Plug.

Can you describe this instrument for us?

-Chuck

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.

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


Chuck is correct... on the "C" model, the a.c. probe uses a 1/4" stereo
plug. The A, B, and MIL models are hard-wired either directly or via a
screw-on terminal assembly.

On Sep 4, 1:30 am, Chuck Harris wrote:

HP410LR? That's a new one to me. I am aware of the 410A, 410B, and 410C,
but not the LR. The 410(A,B,C) have their DC/Ohms probes wired directly to
the instrument, and their AC probe has a vacuum tube diode in it, and plugs
in by way of a Stereo Phone Plug.

Can you describe this instrument for us?

-Chuck

Sorry, it's a HP 400LR, a rack mount version of the 400L.

My unit has binding posts.

wrote in message
ups.com...
On Sep 4, 1:30 am, Chuck Harris
wrote:

HP410LR? That's a new one to me. I am aware of the
410A, 410B, and 410C,
but not the LR. The 410(A,B,C) have their DC/Ohms probes
wired directly to
the instrument, and their AC probe has a vacuum tube
diode in it, and plugs
in by way of a Stereo Phone Plug.

Can you describe this instrument for us?

-Chuck

Sorry, it's a HP 400LR, a rack mount version of the 400L.

My unit has binding posts.


The 400 series meters are AC meters, they do not have
DC or resistance ranges. The 400L is the same meter as the
400D and H other than the special meter movment which
displays the voltage on a logrithmic scale and has a linear
decibel scale uppermost. It does not need any special probes
or accessories. The meter movment is a 1% tracking meter
movement with a mirror scale to eliminate parallax similar
to that used on the 400H. BTW, the only difference between
the 400D and 400H is the meter movement and use of a mirror
scale on the meter. Meters made after -hp- introduced
taught-band meters all have the same tracking accuracy since
each meter was individually calibrated by machine. The only
difference here is the use of a mirror scale on the 400H,
the 400D will also track to 1%.
There were at least three versions of the circuit used
in 400D and H meters so you must get a handbook for the
serial number series you have. The later meters used a
circuit which is substantially different than the early
meters.


--
---
Richard Knoppow
Los Angeles, CA, USA

"Richard Knoppow" wrote in message
...
The 400 series meters are AC meters, they do not have
DC or resistance ranges. The 400L is the same meter as the
400D and H other than the special meter movment which
displays the voltage on a logrithmic scale and has a linear
decibel scale uppermost. It does not need any special probes
or accessories.

Richard is correct. May I add that my HP400H, the model with linear scales,
was full of black plastic encapsulated paper capacitors (sometimes called
bumblebees or black beauties). These capacitors are well known for their
failure rates. There may be a reason you got a good price on your meter.

--Chuck N7RHU

On Sep 4, 12:03 pm, "Chuck" wrote:

Richard is correct. May I add that my HP400H, the model with linear scales,
was full of black plastic encapsulated paper capacitors (sometimes called
bumblebees or black beauties). These capacitors are well known for their
failure rates. There may be a reason you got a good price on your meter.


"Cheap" meaning free is about the best price one can obtain.

Shouldn't be hard to replace the caps, right? Am I missing something
here?

wrote:
On Sep 4, 12:03 pm, "Chuck" wrote:

Richard is correct. May I add that my HP400H, the model with linear scales,
was full of black plastic encapsulated paper capacitors (sometimes called
bumblebees or black beauties). These capacitors are well known for their
failure rates. There may be a reason you got a good price on your meter.


"Cheap" meaning free is about the best price one can obtain.

Shouldn't be hard to replace the caps, right? Am I missing something
here?

Nope, very easy. Just don't use disk ceramics. Something in a polyester,
or polypropylene would do nicely.

"Chuck Harris" wrote in
message ...
wrote:
On Sep 4, 12:03 pm, "Chuck"
wrote:

Richard is correct. May I add that my HP400H, the model
with linear scales,
was full of black plastic encapsulated paper capacitors
(sometimes called
bumblebees or black beauties). These capacitors are
well known for their
failure rates. There may be a reason you got a good
price on your meter.


"Cheap" meaning free is about the best price one can
obtain.

Shouldn't be hard to replace the caps, right? Am I
missing something
here?

Nope, very easy. Just don't use disk ceramics. Something
in a polyester,
or polypropylene would do nicely.


I am curious why you recommend against using disc
ceramics.
BB's are found in a lot of high-quality equipment. They
were supposed to be high-performance deluxe caps when they
were sold but very quickly got a well deserved bad
reputation.


--
---
Richard Knoppow
Los Angeles, CA, USA