Repair attenuator switch
I/P & O/p are 50Ohms.
It has switches which controls attenuation. Switches has damaged & OEM don't support.
Please find image attached for the details about switches & attenuator.
Also anybody suggest me how should I proceed in repairing this attenuator?
If I use any ordinary toggle switch what care should I took?
Any specific switch recommendation?
Any supplier recommendation?
Any suggestion will be helpful
Thanks.
Abhishekabs
I don't think the internal switched attenuator is controlled directly by the mechanical switches showed in the image (these switches do not work at higher frequencies as 2GHz). Definitely they bias and control some PIN diodes. You need to follow the schematic (if you have one) and find the fault.
If the attenuator use PIN diodes, can be used any kind of similar mechanical switch to replace the broken one.
Because this equipement is not profesional any DPDT that is small enough is OK.
Hi Vfone.
Its not PIN diode. The switches used here are made by OEM themselves.
The switch ( slide) from one pad to other pad. there is a sprint inside.
Its really nicely built mechanical attenuator.
Hello Borber,
Can you please tell me any supplier name who supply good quality & low loss DPDT switch.
Added after 6 minutes:
Just want to add.
The attenuator & switch is professional make.
They are not soldering the switch to PCB.
So my concern is if I solder any DPDT switch to board. How I am going to close the enclosure!
I am thinking may be I have to make change in hole of cover or make my own new cover,
Try to find one between these:
http://si.farnell.com/jsp/search/bro...0002%2B1003465
I doubt, that the attenuator will still achieve 2 GHz bandwidth after replacing the switch with a standard DPDT device.
The series inductance must be expected considerably higher, the switch elements hardly have a trace width like the
shown contact slider. Sorry.
Agreed... in my experience with all those styles of switched attenuators they are really good for HF DC - 50MHz, start getting additionally lossy at 150MHz and by 300-400 MHz almost totally useless as the the additional losses inserted by the switch contacts often equates to more than what the lumped resistances equals.
This results in the fact that the attenuation amounts indicated on the unit for each switch position is almost totally irrelevent and unreliable.
for reliable results particularly above 1GHz this is the sort of attenuator you need....
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by all means repair the one you have but dont expect any accurate results for UHF or SHF :)
take care
Dave
VK2TDN
From your post, it's not clear what's exactly defective of the original design.
Are you sure that it can't be reconstructed?
FvM you may look here:
http://lea.hamradio.si/~s53mv/spectana/sa.html
Analyzer and tracking gen works up to 1.75GHz. Input and output attenuators are made with togle switches. Attenuator precision is in range of .5dB. Resistors are standard 5%.
I assembled this project about 10 years ago.
Hi!
For some sceptical people:
You can apply a newest miniature Reed switch_its as I remember ca 5-8mm "long"_ and the toggle does only move 1 or 2 small magnets...
You can order by Farnel, Schuricht... small one magnets from 1.8x1.8x ca10mm...
BTW; very fine toggle switches are from APT, C&K and some other Japs as NKK, most are by Farnell & like "Distis" to order...
K.
Wow guys
Thanks for the replies.
Hello Borber,
I have studied the design made by Mr Matjaz ( S53MV)
He does says that it is possible to go up to 2GHz but it is very hard to find good quality & low loss switches.
That is why I posted asking about supplier.
Hi FVM
The switch spring is broken so it not working.
We want to repair it. We searched a lot but the similar switch is not available in market. Its custom made I guess.
Hello Davenn
See the attached image
they are claiming that it is DC to 2GHz.
Also FVM forgot to add one thing
If you check the link provided by mr. Borber
you will find that S53MV has added capacitor to compensate the losses.
I am thinking of doing the same but dont know whether it will work or not since its not my design
At least for the direct way, no capacitor can cancel the switch inductance.
I hope however, that Borber is right. Replacing only one switch means less losses than using miniature switches for the complete attenuator.
The design description also tells about additional ground planes to reduce the switch inductance.
In any case, only a precise measurement will reveal the actual bandwidth.
S53MV switch is available:
http://b2c.hte.si/article.asp?ArticleID=6093
Switch block measures are wxlxh 9.3x8.3x7.
If you decide I can send you few pieces.