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E4406A Input Attenuator

 

Hi All,

I'm back from vacation and I had a chance to check out the attenuator in the front of the unit - It tests out fine, as does the N Type jack/

I tried wiggling the hard line to see if that made any difference and it didn't but that really doesn't mean much - I don't have anything of the type that connects tot he RF board so I can't swap it out.

U38 is the relay that switches from the Input to the 50MHz cal signal - it's marked as a 1GG7-4128 but my search-fu is weak and I can't find anything out about it. Anyone happen to know if there are replacements available?

Any other suggestions? Am I barking up the wrong tree?

Thanks,

TonyG
Tom Miller
 

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This would have been the first place I would have looked at. I have seen these Gaas switches lose level in the 20 dB range on one port before. Try to save the original part if possible in case that is not the cause.
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This is the exact part. Will run you about $25 or so.
?
This is very close but is only speced to 3 GHz. I bet it will work just fine. Only about $5. If you install this part and the low frequencies work fine, then you can replace it with the better part.?
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----- Original Message -----
Sent: Friday, July 28, 2017 9:14 PM
Subject: [hp_agilent_equipment] Re: E4406A Input Attenuator

?

Hi All,

I'm back from vacation and I had a chance to check out the attenuator in the front of the unit - It tests out fine, as does the N Type jack/

I tried wiggling the hard line to see if that made any difference and it didn't but that really doesn't mean much - I don't have anything of the type that connects tot he RF board so I can't swap it out.

U38 is the relay that switches from the Input to the 50MHz cal signal - it's marked as a 1GG7-4128 but my search-fu is weak and I can't find anything out about it. Anyone happen to know if there are replacements available?

Any other suggestions? Am I barking up the wrong tree?

Thanks,

TonyG
 

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Thanks Tom – I bought a couple of the low end versions (just in case one doesn’t work) – I’ll swap it out and see.


Thanks again for the help.

?

TonyG

?

Sent from for Windows 10

?
 

As a follow-up, I removed the relay from the RF Board and then just bridged the Cal & RF input pads using a piece of wire. The unit passes its self-tests with the wire bridging AT1 (pad 2) and the 50MHz Cal pad (pad 8) , it also shows the RF input very close to what the signal generator is putting out (only 50Mhz as I'm using a piece of wire held in my hand).

The one strange thing was that the control voltages for U38 were +/- 9V rather than +5v & 0V, I'm not sure if that is indicative of problem further up the chain that could have been causing the relay to fault.

TonyG
 

Hi All.

In the continuation of the repair of our E4406.... I have a problem with the?front panel control?and the PS unit. The?repairing?experience of measurement instruments already exists, but there are no E4406 schemes.?While I found only RF unit clip.?Can someone help with the others?clips?

Alexander
 

Hello,

I have replaced the input switch on a E4406A by a MGS-71018 but I got the same problems as described on Youtube in the different steps of a E4406A repair :

https://www.youtube.com/watch?v=C864ibb65YI&t=1015s

I found that the control lines NEED to provide -5V for the MGS-71018 instead of the -8/9V on the original GG7-4128. To solve the problem , I have installed one 3,9V zener diode on each line between the resistors R333 & R334 and the two control pins of the MGS-71018

I found also that there is another BIG difference between the MGS-71018 and the GG7-4128 : the control lines on the E4406A must be crossed for the MGS-71018 .

So the final wiring is :

R333 - 3,9V zener diode - pin 1
R334 - 3,9V zener diode - pin 3

73s Eric
 

Hi all,

I'm sticking my nose in this one since I have an E4406A with the same problem.? Does this repair have staying power?? How difficult is this to perform?

I'd like mine to work properly so any help is appreciated.

Thanks
 

I'm not an expert on this, but keep me updated on the results. If it
is one of the standard attenuators, it can be repaired (carefully) but
if it is sealed, probably a big problem. Send me a picture of the
attenuator and I can give you more information.

Cheers!

Bruce

Quoting "mill_glen_chevy via groups.io" <brstpr@...>:

Hi all,

I'm sticking my nose in this one since I have an E4406A with the
same problem.? Does this repair have staying power?? How difficult
is this to perform?

I'd like mine to work properly so any help is appreciated.

Thanks

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