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

Richard Knoppow wrote:
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.

Disk ceramics, particularly Z5U, or X7R, are a bad idea in any
signal path. The feature that gives them high capacitance for
their size also makes them highly piezoelectric: meaning they change
physical dimension with applied voltage. This large change in
dimension makes the capacitance non linear with voltage, and also
makes the capacitor's power dissipation change with applied signal.
That means distortion.

NPO's behave ok, but are of such low values that they would never
be able to substitute for a capacitor such as a BB.

I have used Z5U ceramic capacitors in high signal areas and actually
heard them "sing" along with the signal. Not a good thing!

Their capacitance is also extremely sensitive to temperature, which
makes them useless in most timing applications. [I did use one once
as a temperature transducer in a cheapy RF telemetry device...]

They work adequately in logic circuits as power supply bypass.

BB's are actually a pretty good capacitor, but they have a couple
of failure mechanisms that render them useless over time. They
are an oil filled paper capacitor with a black epoxy case. If you
look at the banded end of the capacitor, you will notice the lead
has a bulge where it leaves the case. That is actually a piece of
brass tubing that was used in filling the case with oil. After the
case was filled, the lead was stuck into the hole, swaged to keep
it from falling out, and then soldered shut. The problem comes when
the BB's banded lead is soldered into the circuit. If no heatsinking
is used, the solder seal melts, and the oil spoils the seal. From
that point forward, the oil will seep out of the capacitor, and moist
air will seep in... it's a slow process that takes many thermal cycles,
but we are talking about old stuff here. The other failure mechanism
is the plastic case shrinks over time and breaks the seal around the
leads, and sometimes even splits the case into pieces.

The BB's are all bad by now, and should be replaced on sight, but when
they were new, they were a nice high performance capacitor.

-Chuck