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Re: 8558B centre frequency wildly unstable above 1250MHz

tcxo
 

Congratulations Dick!

It might be helpful to the rest of us to know the details of how you injected the cleaner. Did you drill a hole into the case? Or???

Cheers!
Greg

----- Original Message -----
From: ferrymanr
To: hp_agilent_equipment@...
Sent: Monday, August 29, 2011 4:23 AM
Subject: [hp_agilent_equipment] Re: 8558B centre frequency wildly unstable above 1250MHz



Found that a new Bourns 10 turn pot is rather expensive so took the risk of injecting a little jungle juice into it. Now the 8558B is back to normal. I love simple faults.
Dick G4BBH

--- In hp_agilent_equipment@..., "tcxo" <tcxoe@...> wrote:

Noisy / Intermittent / Bad tuning potentiometer?

-Greg

----- Original Message -----
From: ferrymanr
To: hp_agilent_equipment@...
Sent: Sunday, August 28, 2011 4:26 PM
Subject: [hp_agilent_equipment] 8558B centre frequency wildly unstable above 1250MHz



I have an 8558B which becomes totally unstable if the centre frequency is set above about 1250MHz at any span setting. If the span is sufficiently wide it is clear that the SA it is covering perfectly up to about 1550MHz or 1600MHz with some loss of sensitivitity at the top end. When the centre frequency is set above about 1250MHz the frequency display becomes random from blank up to some random number. This indicates to me that the control voltage is unstable above that frequency setting. The display looks like it is jumping all over the spectrum (have I discovered 'spread spectrum').
Any suggestions as to a likely cause or common problem before I delve into the murky depths.
Thanks
Dick G4BBH
Are plotters still useful?

 

What do you use to record outputs from HP test equipment?
I have two plotters (7045B single & 7046B dual pen) but I simply use my camera to photograph the screen. The thought of ink and paper is a turn off, and pens are always a problem. Also these analog plotters would not plot a scale; they must be carefully calibrated and the units written in on graph paper.
I also have an HPIB plotter (7475A) that might work with some of my gear like the 8566A spec analyzer or 8505A Network Analyzer, but what about the 4815A Vector Impedance Meter?
Is there an interface to a modern printer?
Re: 8558B centre frequency wildly unstable above 1250MHz

ferrymanr
 

Found that a new Bourns 10 turn pot is rather expensive so took the risk of injecting a little jungle juice into it. Now the 8558B is back to normal. I love simple faults.
Dick G4BBH

--- In hp_agilent_equipment@..., "tcxo" <tcxoe@...> wrote:

Noisy / Intermittent / Bad tuning potentiometer?

-Greg

----- Original Message -----
From: ferrymanr
To: hp_agilent_equipment@...
Sent: Sunday, August 28, 2011 4:26 PM
Subject: [hp_agilent_equipment] 8558B centre frequency wildly unstable above 1250MHz



I have an 8558B which becomes totally unstable if the centre frequency is set above about 1250MHz at any span setting. If the span is sufficiently wide it is clear that the SA it is covering perfectly up to about 1550MHz or 1600MHz with some loss of sensitivitity at the top end. When the centre frequency is set above about 1250MHz the frequency display becomes random from blank up to some random number. This indicates to me that the control voltage is unstable above that frequency setting. The display looks like it is jumping all over the spectrum (have I discovered 'spread spectrum').
Any suggestions as to a likely cause or common problem before I delve into the murky depths.
Thanks
Dick G4BBH
Re: 8558B centre frequency wildly unstable above 1250MHz

ferrymanr
 

Bang on Greg. Slid the plug-in forward and measured the pot as it is very easy to access. Looks as if I will have to locate another. It looks like a standard Bourns 10 turn job but will consult the manual.
Dick G4BBH

--- In hp_agilent_equipment@..., "tcxo" <tcxoe@...> wrote:

Noisy / Intermittent / Bad tuning potentiometer?

-Greg

----- Original Message -----
From: ferrymanr
To: hp_agilent_equipment@...
Sent: Sunday, August 28, 2011 4:26 PM
Subject: [hp_agilent_equipment] 8558B centre frequency wildly unstable above 1250MHz



I have an 8558B which becomes totally unstable if the centre frequency is set above about 1250MHz at any span setting. If the span is sufficiently wide it is clear that the SA it is covering perfectly up to about 1550MHz or 1600MHz with some loss of sensitivitity at the top end. When the centre frequency is set above about 1250MHz the frequency display becomes random from blank up to some random number. This indicates to me that the control voltage is unstable above that frequency setting. The display looks like it is jumping all over the spectrum (have I discovered 'spread spectrum').
Any suggestions as to a likely cause or common problem before I delve into the murky depths.
Thanks
Dick G4BBH





[Non-text portions of this message have been removed]
Re: 8558B centre frequency wildly unstable above 1250MHz

tcxo
 

Noisy / Intermittent / Bad tuning potentiometer?

-Greg

----- Original Message -----
From: ferrymanr
To: hp_agilent_equipment@...
Sent: Sunday, August 28, 2011 4:26 PM
Subject: [hp_agilent_equipment] 8558B centre frequency wildly unstable above 1250MHz



I have an 8558B which becomes totally unstable if the centre frequency is set above about 1250MHz at any span setting. If the span is sufficiently wide it is clear that the SA it is covering perfectly up to about 1550MHz or 1600MHz with some loss of sensitivitity at the top end. When the centre frequency is set above about 1250MHz the frequency display becomes random from blank up to some random number. This indicates to me that the control voltage is unstable above that frequency setting. The display looks like it is jumping all over the spectrum (have I discovered 'spread spectrum').
Any suggestions as to a likely cause or common problem before I delve into the murky depths.
Thanks
Dick G4BBH
8558B centre frequency wildly unstable above 1250MHz

ferrymanr
 

I have an 8558B which becomes totally unstable if the centre frequency is set above about 1250MHz at any span setting. If the span is sufficiently wide it is clear that the SA it is covering perfectly up to about 1550MHz or 1600MHz with some loss of sensitivitity at the top end. When the centre frequency is set above about 1250MHz the frequency display becomes random from blank up to some random number. This indicates to me that the control voltage is unstable above that frequency setting. The display looks like it is jumping all over the spectrum (have I discovered 'spread spectrum').
Any suggestions as to a likely cause or common problem before I delve into the murky depths.
Thanks
Dick G4BBH
Re: Want to buy: HP 3325A attenuator board

 

Hi Dickson,

Yes, my attenuator board has the Rev C part number as you surmised below. However the exposed circuit traces appear to be gold plated.

The serial number of my unit starts with 1748A13xxx, so I think that it was produced fairly early in that product's lifecycle.

Patrick Wong AK6C

--- In hp_agilent_equipment@..., "Dickson" <dicksonfuhk@...> wrote:

I think Patrick's attenuator board is the newer "03325-66523 Rev C" which used the relay made by Aromat (Japan). I think Aromat is being merged with the Japanese giant Panasonic.

It seems to me "Rev C" is a cost down version because it is not longer having the gold plated PCB.
Re: HP436A LED Display Driver IC - HP1820-1361 - 9374DC - Where to get?

 

You might try Tanner Electronics in Dallas. Jimmy Tanner used to carry many of the old logic families, and he might still have some around. I think he still has a website, but you will have to phone or email for part info.

Dave

On 8/28/2011 2:42 PM, mrcschrdrs wrote:
According to the 436 manual, 1820-1361 is a Fairchild 9374DC.
From the schematic it looks like some BCD to 7 segment decoder.
Quite a different beast then the 75491 which seems to be just 4 drivers.

Now where to get one - salvage one from an other 436?

Marc.
--- In hp_agilent_equipment@..., francesco messineo<francesco.messineo@...> wrote:
Hello,

On 8/28/11, m_elec_guy<mm777888@...> wrote:
Hi Group, I've got a HP436A with a defective LED display decoder IC
(A1U1...U4 - all same type of chip). Only 1 IC is bad, the others are fine.
I can't seem to find a replacement or substitute. Does anyone know where
one can get a replacement?
From the cross reference I have, it's reported as equivalent to
SN75491 display driver.

Best regards

Frank


------------------------------------

Yahoo! Groups Links
Re: HP436A LED Display Driver IC - HP1820-1361 - 9374DC - Where to get?

 

On 8/28/11, mrcschrdrs <mrcschrdrs@...> wrote:

According to the 436 manual, 1820-1361 is a Fairchild 9374DC.
From the schematic it looks like some BCD to 7 segment decoder.
ops, then the cross reference floating around on the internet isn't at
all accurate.
You can try the NTE8374 equivalent or try to adapt a CD4511 (which is
BCD latch/decoder/driver, you'd need to make an adapter board I
think).

Best regards

Frank
Re: HP436A LED Display Driver IC - HP1820-1361 - 9374DC - Where to get?

Richard W. Solomon
 

And again ... they are available "over there" !!

73, Dick, W1KSZ

-----Original Message-----
From: mrcschrdrs <mrcschrdrs@...>
Sent: Aug 28, 2011 12:42 PM
To: hp_agilent_equipment@...
Subject: [hp_agilent_equipment] Re: HP436A LED Display Driver IC - HP1820-1361 - 9374DC - Where to get?


According to the 436 manual, 1820-1361 is a Fairchild 9374DC.
From the schematic it looks like some BCD to 7 segment decoder.

Quite a different beast then the 75491 which seems to be just 4 drivers.

Now where to get one - salvage one from an other 436?

Marc.
--- In hp_agilent_equipment@..., francesco messineo <francesco.messineo@...> wrote:

Hello,

On 8/28/11, m_elec_guy <mm777888@...> wrote:
Hi Group, I've got a HP436A with a defective LED display decoder IC
(A1U1...U4 - all same type of chip). Only 1 IC is bad, the others are fine.
I can't seem to find a replacement or substitute. Does anyone know where
one can get a replacement?
From the cross reference I have, it's reported as equivalent to
SN75491 display driver.

Best regards

Frank



------------------------------------

Yahoo! Groups Links
Re: HP436A LED Display Driver IC - HP1820-1361 - 9374DC - Where to get?

mrcschrdrs
 

According to the 436 manual, 1820-1361 is a Fairchild 9374DC.
From the schematic it looks like some BCD to 7 segment decoder.

Quite a different beast then the 75491 which seems to be just 4 drivers.

Now where to get one - salvage one from an other 436?

Marc.

--- In hp_agilent_equipment@..., francesco messineo <francesco.messineo@...> wrote:

Hello,

On 8/28/11, m_elec_guy <mm777888@...> wrote:
Hi Group, I've got a HP436A with a defective LED display decoder IC
(A1U1...U4 - all same type of chip). Only 1 IC is bad, the others are fine.
I can't seem to find a replacement or substitute. Does anyone know where
one can get a replacement?
From the cross reference I have, it's reported as equivalent to
SN75491 display driver.

Best regards

Frank
Re: HP436A LED Display Driver IC - HP1820-1361 - 9374DC - Where to get?

Richard W. Solomon
 

There are two listings for the SN75491 over on the "evil empire".

73, Dick, W1KSZ

-----Original Message-----
From: francesco messineo <francesco.messineo@...>
Sent: Aug 28, 2011 11:54 AM
To: hp_agilent_equipment@...
Subject: Re: [hp_agilent_equipment] HP436A LED Display Driver IC - HP1820-1361 - 9374DC - Where to get?

Hello,

On 8/28/11, m_elec_guy <mm777888@...> wrote:
Hi Group, I've got a HP436A with a defective LED display decoder IC
(A1U1...U4 - all same type of chip). Only 1 IC is bad, the others are fine.
I can't seem to find a replacement or substitute. Does anyone know where
one can get a replacement?
From the cross reference I have, it's reported as equivalent to
SN75491 display driver.

Best regards

Frank


------------------------------------

Yahoo! Groups Links
Re: HP436A LED Display Driver IC - HP1820-1361 - 9374DC - Where to get?

 

Hello,

On 8/28/11, m_elec_guy <mm777888@...> wrote:
Hi Group, I've got a HP436A with a defective LED display decoder IC
(A1U1...U4 - all same type of chip). Only 1 IC is bad, the others are fine.
I can't seem to find a replacement or substitute. Does anyone know where
one can get a replacement?
From the cross reference I have, it's reported as equivalent to
SN75491 display driver.

Best regards

Frank
Re: HP 1725A oscilloscope, first displayed cycle is weird

 

On 08/28/2011 09:35 AM, honolulusnowwhite wrote:
I know that the vertical output has adjustments for frequency response, but wouldn't those adjustments affect all displayed pulses, not just the first?
Only if the pulses are all similar time scale. Not enough info to say.

If the second pulse is after enough time that all has gone back to steady state
quiet, no more current flowing, then the 2nd pulse should look just like the first,
or suspect the scope and path between, not the generator.

John
Re: FS 54701A Probes

 

I guess no one is interested in these, as I've gotten no offers. If I don't sell them here for a small price, later in the week I'm going to list them on ebay. They seem to fetch a rather ridiculous price there.

As for whether they work, as I said, I have no way to test these. However, they came from a shop that was in the habit of tagging defective equipment and putting it in a back room. These probes were not tagged and were in the shop area with the working equipment. Based on this and the fact that all the other equipment in the shop worked, I'd say that these probes are most likely OK.

--- In hp_agilent_equipment@..., "mojoehand" <mojoehand@...> wrote:

I have two HP 54701A 2.5 GHz Active Probes in plastic cases. They look complete and almost new, but I have no way to test these. I'll sell these cheap, so make me an offer. Shipping within the US will be $10 extra for Priority Mail.
For Sale: Agilent 34330A 30A Current Shunt

Steve
 

This is a new, unused current shunt with the following specs:

DC - 1 kHz +/- 0.3 %
1 kHz - 5 kHz +/- 5.0 %
15 amp: Continuous
30 amp: 15 minutes Max

Priced at $ 50 includes shipping within the U.S.
PayPal is accepted - please reply offline.

Steve
For Sale: HP 85672A cards 1 and 2

Steve
 

I have a set of cards 1 and 2 (missing card 3 of 3) of
the HP 85672A Spurious Response Measurement Utility for use with the following spectrum analyzers:

8560A/E
8561A/B/E
8562A/B/E
8563A/E
8564E
8565E

Asking price $ 50 includes shipping within the U.S. - PayPal is OK.
Please reply offline - thanks.

Steve
HP436A LED Display Driver IC - HP1820-1361 - 9374DC - Where to get?

 

Hi Group, I've got a HP436A with a defective LED display decoder IC (A1U1...U4 - all same type of chip). Only 1 IC is bad, the others are fine. I can't seem to find a replacement or substitute. Does anyone know where one can get a replacement?
Re: Looking for probe tips for an HP8405A Vector Voltmeter

 

If you solve this riddle, I would like to get some as well.

Joe

-----Original Message-----
From: hp_agilent_equipment@...
[mailto:hp_agilent_equipment@...]On Behalf Of m_elec_guy
Sent: Sunday, August 28, 2011 12:08 PM
To: hp_agilent_equipment@...
Subject: [hp_agilent_equipment] Looking for probe tips for an HP8405A
Vector Voltmeter



Hi Group, I was wondering where I could get some probe tips for an HP8405A
Vector Voltmeter? I would like to 3 if possible. Any ideas?
Looking for probe tips for an HP8405A Vector Voltmeter

 

Hi Group, I was wondering where I could get some probe tips for an HP8405A Vector Voltmeter? I would like to 3 if possible. Any ideas?
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