Hi Richard,

You should replace C13 if it is getting hot. You can use three 10 uF 630 volt electrolytics for that. I haven't taken my 200CD down to check the R30/31 situation but it certainly looks like it is normal for them to dissipate quite a bit of power and therefore get hot. I would have thought R30/31 should be wirewound with 10-20 watt ratings.? If the rectifier tube is weak you can replace it with silicon diodes as HP themselves did in the last versions of the 200CD. My copy of the June 1967 manual shows silicon diodes in the power supply but they are drawn backwards!

I'm in Melbourne so hands-on assistance including tube testing (for balance) will depend on whether you can find someone a bit closer.

Regards,

Morris

Thanks Chuck

Its a 10w resistor with about 9w dissipation so I guess it is doing what it was designed to do. As a hobbyist only having worked on a few solid state amplifiers, all you read suggests avoiding such heat in a resistor.?

Richard

On Tue, Nov 9, 2021 at 10:14 AM Frank C. D'Amato - KB2MXV
<kb2mxv@...> wrote:

Thank you Tom

Also, if you really want 14.2, go here:

www.keysight.com/find/iosuite

Click on Previous Versions, and then scroll down to 2006-06-01 Version
14.2.8931.1 and then you can download the 82MB installation file
iolibs_suite_14_2_8931_1_multimedia.exe

Thank you Tom

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Version 15.0 will run on XP.

See

Tom Bryan
N3AJA

Can someone help me find?Agilent IO Libraries Suit 14.2 please.

I need it for a windows XP machine.

Thanks

Hi Mat
Ideal for supporting light instruments such as 2 off 437 power meters but I
wooden risk 2 off 3314 Function generators
But then 2 side supports with a bit of metal spanning them is probably less
expensive
Regards Paul

On 11/8/21 5:58 PM, Matt Huszagh wrote:

Did you make your own supports from angle irons, Dave? It sounds like
getting 1.5 in sq angle irons 1/8" thick and then drilling custom holes
for mounting to the rack could work well here. I expect the trick is
drilling the holes at just the vertical height so that the modules sit
on the angle iron but the flanges still mount to the front panel.

No, I'm too much of a perfectionist (read: snob) (and have too little
free time) to do that. I get proper rack rails, usually Navepoint these
days.

If it's not too much trouble, would you mind sending me a link to the
Navepoint rack rails you get? I think I'm not finding quite the right
thing.

These are the ones I use for most things:



I first spotted them (and Navepoint as a company) on eBay, so I just ended up buying them there.

As I mentioned earlier, they are a bit software than I'd like, but they're otherwise well-made and have been very handy.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

On 11/9/21 8:42 AM, Chuck Harris wrote:

You need to bear in mind that power resistors of the
ceramic wirewound, or metal film, variety are heaters.

They are designed to get very hot at their *rated* power.
200C is typical. Most wirewound resistors can be made
to glow red hot without anything more than a little
discoloration. The wire used is typically nichrome
heating element wire.

For safety issues, engineers usually don't want anything
that hot inside of their chassis, but in cases where
they need bulk power dissipation, sometimes they do.

Assuming that these resistors are DC load, resistors,
measure the voltage across the resistor using a dc meter,
and plug that value into Power = V*V/R, and if Power
is less than the resistor's rated value, you are probably
ok. Engineers typically spec their resistors to run at
about 1/2 the manufacturer's rated power.

There is no point in paying for a large power resistor if
you don't need a large power resistor.

-Chuck Harris

Finally some common sense! (I don't know what kind of resistor
is in the unit, of course.)? Doug--WA2SAY--retired RF engineer

On Tue, 09 Nov 2021 04:04:39 -0800 "Richard Merifield"
<coitboy2000@...> wrote:

Thanks Morris, yes I will transfer it over to 240V.

...Before I did so I noticed R30 was
scolding hot like my other unit. I wonder whether they ever
considered high wattage resistors for R30 ?

On 11/9/21 12:15 PM, Matt Huszagh wrote:

Another question: is there a rule of thumb for when a module requires
support rails in addition to the flange or ear mounts?

There's no real rule of thumb. Some people insist that cantilevered mount via ears alone is never safe, but a lifetime of seeing equipment mounted that way, and having a lab full of some and a computer museum full of more, much of it factory, I say that's BS. "Use judgment".

It also pays to check the documentation, sometimes mounting requirements are covered.

If it's relevant,
this would be for a NavePoint 42U rack:

That looks nice. But you're in the USA in 2021: Companies are going tits-up left and right, and datacenters are being decommissioned and consolidated everywhere. With a little patience and smart snooping you should have no trouble at all finding a good solid rack for free, or very cheap, unless you're really out in the sticks. (which is a separate problem, with a separate solution)

In particular, keep an eye on local GovDeals listings, in particular university surplus if you're near a decent-sized university.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

This has been converted to read the output voltage of a HeNe laser power supply e.g. Voltex Inc S-28-LI unit.

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Another question: is there a rule of thumb for when a module requires
support rails in addition to the flange or ear mounts? If it's relevant,
this would be for a NavePoint 42U rack:



Thanks
Matt

Yes - that is probably the 08640-60193 processor and it is the "modern" version not the cylinder head CPU.

Should be good

Cheers!

Bruce

Quoting RubenRubio <rubenrb2019@...>:

My 'new' 8341A just arrive

The processor board looks alike the modern version, but maybe you can help me identifying that :)

Regards,
R.

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Jim,

The connector looks like the high voltage connector typically used on HeNe gas laser tubes, or on corona wire HV power supplies for laser printers.

The high voltage dropping resistor, the RMS conversion module, and the pink connecting cables also suggest that it was used for measuring a high voltage AC supply.

Dave

I have 2 of these 8642A stacked on top of eachother on my shack table. They are both "feet-less", being ex-rackmount units. Never any problems with temperature rising too much. Mind you, these generators are MILspeced, max speced ambient temp is 50degrees C.
I gave up on working in my shack during last years heatwave, ambient was like 37C or so. The HP's could not care less.

Wilko