?

Hi folks,

mayby I'm stupid, but I need guidance.
I want to make sure my HP85101 is set for 220V before connecting it to mains and powering it up.
The line module seems pretty much standard across the HP equipment of that age.
A lever next to the mains socket removes the fuse. Below the lever there is a little pcb plug that allows to change the voltage setting.
Is there a trick to remove that card? It seems to be stuck. Is there a locking mechanism or do I just not pull hard enough?
I don't want to break anything.

Thanks, Tom

On May 27, 2022, at 1:20 PM, tom_iphi via groups.io <iphi@...> wrote:

?Hi folks,

mayby I'm stupid, but I need guidance.
I want to make sure my HP85101 is set for 220V before connecting it to mains and powering it up.
The line module seems pretty much standard across the HP equipment of that age.
A lever next to the mains socket removes the fuse. Below the lever there is a little pcb plug that allows to change the voltage setting.
Is there a trick to remove that card? It seems to be stuck. Is there a locking mechanism or do I just not pull hard enough?
I don't want to break anything.

Thanks, Tom

?

Hi folks,

mayby I'm stupid, but I need guidance.
I want to make sure my HP85101 is set for 220V before connecting it to mains and powering it up.
The line module seems pretty much standard across the HP equipment of that age.
A lever next to the mains socket removes the fuse. Below the lever there is a little pcb plug that allows to change the voltage setting.
Is there a trick to remove that card? It seems to be stuck. Is there a locking mechanism or do I just not pull hard enough?
I don't want to break anything.

Thanks, Tom

Hi Dmitry

?

Whilst I share your concerns may I say that the HP fault finding guidance is based around having a set of their 8622A or 8623A PCB card extenders available.Under most circumstances using the card extenders will leave the power supply loads in place and limit the extent to which the voltages can rise.

?

?

The biggest problem that I see with most SMPSU repairs is a lack of understanding as to how they work and the limitations placed on their control circuitry.? I would suggest reading the excellent posting by Dave G8KBV in the previous 8622A repair thread, the key point is only one voltage control loop.

On 26 May 2022, at 18:54, Lothar baier <Lothar@...> wrote:

?I haven’t seen any 8478B used as transfer standard ?, we used them with some special option to calibrate the 50MHz reference on 43x series meters , for sensor calibration we used a weinschel system2 , Yes NIST - if you can afford it - ?will calibrate any sensors that are using a self nulling bridge circuit which certainly includes the 8478B as well as the weinschel sensors

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Dave McGuire via groups.io
Sent: Thursday, May 26, 2022 3:31 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP/Agilent/Keysight 8478B thermistor mount

On 5/26/22 16:10, Lothar baier wrote:

i wouldnt call it a transfer standard , weinschel/tegam makes sensors

that use the same principle that are heated (1109/1111)? that are used

with system 2 units to calibrate sensors , they are outrageously

expensive

??They certainly can be, and certainly are, used as transfer standards.
?Further, NIST will calibrate them. (they won't calibrate any other type of RF power sensor, unless something has changed very recently)

???????????-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

I haven’t seen any 8478B used as transfer standard , we used them
with some special option to calibrate the 50MHz reference on 43x
series meters , for sensor calibration we used a weinschel system2 ,
Yes NIST - if you can afford it - will calibrate any sensors that are
using a self nulling bridge circuit which certainly includes the 8478B
as well as the weinschel sensors

-----Original Message-----
From: [email protected]
<[email protected]> On Behalf Of Dave McGuire
via groups.io
Sent: Thursday, May 26, 2022 3:31 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP/Agilent/Keysight 8478B
thermistor mount

On 5/26/22 16:10, Lothar baier wrote:

i wouldnt call it a transfer standard , weinschel/tegam makes sensors
that use the same principle that are heated (1109/1111)? that are
used with system 2 units to calibrate sensors , they are outrageously
expensive

They certainly can be, and certainly are, used as transfer standards.
Further, NIST will calibrate them. (they won't calibrate any other
type of RF power sensor, unless something has changed very recently)

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

I haven’t seen any 8478B used as transfer standard , we used them with some special option to calibrate the 50MHz reference on 43x series meters , for sensor calibration we used a weinschel system2 , Yes NIST - if you can afford it - will calibrate any sensors that are using a self nulling bridge circuit which certainly includes the 8478B as well as the weinschel sensors

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Dave McGuire via groups.io
Sent: Thursday, May 26, 2022 3:31 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP/Agilent/Keysight 8478B thermistor mount

On 5/26/22 16:10, Lothar baier wrote:

i wouldnt call it a transfer standard , weinschel/tegam makes sensors
that use the same principle that are heated (1109/1111)? that are used
with system 2 units to calibrate sensors , they are outrageously
expensive

They certainly can be, and certainly are, used as transfer standards.
Further, NIST will calibrate them. (they won't calibrate any other type of RF power sensor, unless something has changed very recently)

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

i wouldnt call it a transfer standard , weinschel/tegam makes sensors
that use the same principle that are heated (1109/1111)? that are used
with system 2 units to calibrate sensors , they are outrageously
expensive

Hello,


There is one more issue to consider. Long lines give delays. Once I wanted to measure the loss of a coaxial cable on a vna. Was an interesting experience: no response. Until I realized the receiver had already traveled higher up in frequency at the time the response was back. You need to consider a delay in between frequency steps, long enough so as to give the receiver time to read the response. This is a documented feature (of course).

Good luck,

Harke, PA0HRK


On 26/05/2022 20:09, Tom Lee wrote:

Hi Karin,

"Upper limit" is not as hard a cliff as your question presupposes. Whether or not a given length of cable is too much depends on your acceptance criteria. What are you trying to measure, and to what accuracy do you need to measure it?

When you add cable, you get loss, so that loss subtracts directly from your dynamic range. For example, if you are making meaurements at a gigahertz or so, with RG-213 you can expect to lose about 10dB in each direction, roughly speaking. If you aren't trying to measure small deviations from an exquisitely well-matched load, you'll be fine. If you're trying to resolve small changes in the vicinity of a -60dB S11 null, then you may find the measurement challenging.

The other factor to consider with a long length of cable is that it isn't rigid, so stability of your measurement can be affected. And if you are doing a lengthy set of measurements, temperature effects can come into play as well. Whether these are "don't cares" or showstoppers depends on what you can tolerate. If you can tolerate large error bars, your measurement problems become much less severe. If you're trying to make publication-quality measurements, you may find that difficult.

Good luck!

--Cheers,
Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070

On 5/26/2022 09:45, Karin Johnson wrote:

Hello Group:
I have an 8753C and am wondering what the upper limit on cable length would be if I place the cal standards at the end of a cable to do remote measurement of S11.?? In other words I am using SOL, with the cal standards placed at the end of a 100 foot length of RG-213.? Theoretically placing the measurement plane at the end of the cable.? I have already done this and the results seem to be accurate relative to an actual measurement at the that physical place.
I hope I have explained this issue sufficiently.
Regards,
Karin Johnson

BTW: I have had an account on the Keysight forums in the past and have recently tried to login to that site, but It won't let me.? Possibly password have changed, and I cannot create a new account.? I have posted with Keysight support and hope they return the email.

first of you have to consider that the 8478B just as the older 478 series requires a lot of manual assembly steps as it was designed in a time when there was no such thing as surface mount parts or automated assembly . one also has to consider that the QTY of those sold by keysight now is by far less than it was 10 or 20 years back ,? as bruce already pointed out those sensors nowadays are not mainstream anymore but rather used in calibration labs