Topics

Tektronix 492BP


 

Hi, I recently adquire this unit I had a diplexder and WG so to be able to increase the 21GHz frequency but this unit does not go over the 21GHz limit. It does not appear to have any options but it does has the external mixer connector and 1st and 2nd LO. Is there any way I can increase its limit?
thanks.
KE6OJE.


John Miles
 

What happens when you try to enter a frequency higher than 21 GHz?

-- john, KE5FX

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Mike Yepes
Sent: Wednesday, January 13, 2021 7:28 AM
To: TekScopes@groups.io
Subject: [TekScopes] Tektronix 492BP

Hi, I recently adquire this unit I had a diplexder and WG so to be able to
increase the 21GHz frequency but this unit does not go over the 21GHz limit.
It does not appear to have any options but it does has the external mixer
connector and 1st and 2nd LO. Is there any way I can increase its limit?
thanks.
KE6OJE.



 

Frequency not in rage ignored. Also I cannot move the band higher than 15-21GHz. When I press the buttom external mixer it said: UNDEFINED FUNTION.


John Miles
 

Check the DIP switches in the CPU section for continuity, as well as the ones on the Z-axis board. Sounds like one or more of them may have failed, and the instrument thinks it doesn't have the external mixer jack.

-- john, KE5FX

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Mike Yepes
Sent: Wednesday, January 13, 2021 10:19 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tektronix 492BP

Frequency not in rage ignored. Also I cannot move the band higher than 15-
21GHz. When I press the buttom external mixer it said: UNDEFINED
FUNTION.



 

Check the DIP switches in the CPU section for continuity, as well as the ones
on the Z-axis board. Sounds like one or more of them may have failed, and the
instrument thinks it doesn't have the external mixer jack.
I only have the operators manual. Let me see if I can find the schematics in pdf format somewhere.
I will revise that , thanks a lot.
So all units with the external mixer jacks must provide extended range? Becasue I was told there is an option that eliminted the extended range and this unit had erased the tag for the options so not sure if it may had that option.


 

The only boards with dip switches are the memory board and the vertical digital storage board. I have no idea which ones supposed to be on or off.


Thomas S. Knutsen
 

Start by giving what version no. Your SA gives when starting up. The dip
switches changes between the software versions.

If there is sockets on the front, and the correct cabling inside your SA
has external mixers. There was a different front panel for those without
it, and there is no pushbutton hole nor hole for IF in.
The only strange version is the 75ohm version that has some of the coaxes
inside re-routed and an 75ohm:50ohm transformer with BNC that goes into the
hole where IF input should have been.

BR.
Thomas.


tor. 14. jan. 2021 kl. 17:54 skrev Mike Yepes <theamberco@hotmail.com>:

The only boards with dip switches are the memory board and the vertical
digital storage board. I have no idea which ones supposed to be on or off.





--
With Best regards, Thomas S. Knutsen.

Please avoid sending me Word or PowerPoint attachments.


 

9.1 and 1.1 panel ver.


 


Thomas S. Knutsen
 

That is the same as my 492BP.
If I remember it, I will take the cover off and note the switch settings. By flipping the switches you can get any model no. And any version. Often the switches fails after years and need replacement.

Thomas.

Sendt fra min iPhone

14. jan. 2021 kl. 19:05 skrev Mike Yepes <theamberco@hotmail.com>:

9.1 and 1.1 panel ver.





John Miles
 

It's not a question of them being set incorrectly, it's a question of whether their contacts actually match their settings.

The DIP switches used by Tek in this era are extremely failure-prone due to aging. But normally they are OK until they're toggled on or off for the first time in 20+ years. You can rule out the switches by checking them with an ohmmeter to see if the ones that are in the 'OPEN' position are actually open (i.e., med/high resistance across the contacts.) Likewise for the others, with ~0 ohms expected across the contacts for the switches that are closed.

-- john, KE5FX

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Mike Yepes
Sent: Thursday, January 14, 2021 8:54 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tektronix 492BP

The only boards with dip switches are the memory board and the vertical
digital storage board. I have no idea which ones supposed to be on or off.



Tom Lee
 

I've had the same experience as John, and not only with Tek's instruments. HP gear of that period also seems to suffer from the same affliction. That likely implies that you'd find this in the products of other manufacturers as well.

-- Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 1/14/2021 11:27, John Miles wrote:
It's not a question of them being set incorrectly, it's a question of whether their contacts actually match their settings.

The DIP switches used by Tek in this era are extremely failure-prone due to aging. But normally they are OK until they're toggled on or off for the first time in 20+ years. You can rule out the switches by checking them with an ohmmeter to see if the ones that are in the 'OPEN' position are actually open (i.e., med/high resistance across the contacts.) Likewise for the others, with ~0 ohms expected across the contacts for the switches that are closed.

-- john, KE5FX


-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Mike Yepes
Sent: Thursday, January 14, 2021 8:54 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tektronix 492BP

The only boards with dip switches are the memory board and the vertical
digital storage board. I have no idea which ones supposed to be on or off.






 

Thanks a lot for hte help but the dip switches on those boards are ok. (Vertical digital storage and memory board)


Thomas S. Knutsen
 

You want to check those dip switches again, the alternative may be that the
EPROM is losing its memory, and that's not a fault you want to have.
Could it be that the switches have been fooled with by a former owner?

BR.
Thomas.


tor. 14. jan. 2021 kl. 21:56 skrev Mike Yepes <theamberco@hotmail.com>:

Thanks a lot for hte help but the dip switches on those boards are ok.
(Vertical digital storage and memory board)





--
With Best regards, Thomas S. Knutsen.

Please avoid sending me Word or PowerPoint attachments.


 

May have been unit has been opened before, but works fine up to 21GHz. But what switches do you refer to on what board? Where can I find where the switches suppose to be?


 

I think option 8 remove the extended frequency. This unit may had that as the options tag has been erased as it is old probably 90s.


d.schilling.net@...
 

I dropped i photo here
https://groups.io/g/TekScopes/album?id=259372

Photo says the external mixer enable is on the Z-Axis board S1010-2

<Fingers Crossed>


 

Now I can heard a relay clicking and the external mixer lights glows. But I cant change the bands higher than the 15-21Ghz band, How can I get it to display the higher frequencies?


 

Hi, but now when I do reseat the noise floor is bellow the screen I cant see it and the 100MHz cal signal is -57dBm instead of -20dBm hence I cant do the runtine calibration as it said not cal signal detected. What could of happened?


John Miles
 

You've checked your logamp board for capacitor leakage, right? That's always a risk with the later-model analyzers with post-B030000 serial numbers. If it looks like the photo on page 18 of http://www.ke5fx.com/49x_notes.pdf you have some heavy cleanup work to do.

-- john, KE5FX

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Mike Yepes
Sent: Friday, January 15, 2021 5:33 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tektronix 492BP

Hi, but now when I do reseat the noise floor is bellow the screen I cant see it
and the 100MHz cal signal is -57dBm instead of -20dBm hence I cant do the
runtine calibration as it said not cal signal detected. What could of
happened?