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Author Topic: Who had problem with VHF(S-AV17 or other type) 144Mhz hibride module?  (Read 2107 times)
HG5AZR
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Posts: 0




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« on: January 25, 2013, 11:34:38 AM »

Hi!

1.I like to know that module problem(S-AV17) or not if module has only 40W at 13.5V if hi power set pot is in max position?

I heard the module broken inside and will be no power output.I dont interesting for comment when modul totally dead because it is 100% module problem.I am interesting only when module damaged a little and dont work 100%.Who realised that?

2.Who had this kind of failure when modul has only 10W or 20W or 30W or 40W instead 60W total on 144Mhz band?
My module is not broken inside!



Thanks
               Zoli
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K9YLI
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Posts: 865




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« Reply #1 on: January 26, 2013, 05:59:43 AM »

I found the internal  schematic on line.
There are  2 transistors   in the module..

maybe one is fried,,

experiment.   open the circuit to one and see if  the output changes..
then do the other one..
seperate and  substitute  is how  to fix things...

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HG5AZR
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« Reply #2 on: January 26, 2013, 06:40:36 AM »

Hi!

I opened covers of final module !

My S-AV17 result with multimeter in diode position:
 
3. Tranzistor 1 :
>
> Bazis und Ground is  .021
> Ground und Bazis is  .021

> Bazis(black) und Collector(Red) .878
> Bazis(red) und Collector(black) .639

> Collector(black) und Ground(red) .639
> Collector (red) und Ground(black)  .852



> Tranzistor 2 :
>
> Bazis und Ground is  .017
> Ground und Bazis is  .017


> Bazis(black) und Collector(Red)  from  .350 until 1.750 increase and after stop
> Bazis(red) und Collector(black)   from .350 until .490 increase and after stop

> Collector(black) und Ground(red)   from .350 until .470  increase and after stop
> Collector (red) und Ground(black)  from .350 until 1.750 increase and after stop
 
If you have time please send me your test result for S-AV17 modul.If module died no problem,maybe only broken trace and transistor is works and possible to control with multimeter.
I like to know that my module test is normal value or not?

Thanks
                Zoli
 



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WN2C
Member

Posts: 454




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« Reply #3 on: January 26, 2013, 07:10:35 PM »

Zoli, it has been reported that some times the trace will lift when it gets hot.  Usually at full power.  Some times lower power (5 watts or 10) will work, but when you go to high power(50 watts) then there is no power out. Check the trace under a good magnifying glass, it may be cracked.  If it is, solder it up, put it back in and try it.  Saw this in a Hints and Kinks article.
The SAV-17 may not be produced any longer.  RF Parts has a replacement part number.  I put that info in your other thread. 
Good luck and let us know how you make out!

Rick  wn2c
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WB6BYU
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Posts: 13288




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« Reply #4 on: January 26, 2013, 08:33:01 PM »

I have had a VHF module break and successfully repaired it.

What had happened was that the ceramic substrate (beryllium oxide most likely) had
cracked due to overheating.  The symptoms will depend on the exact location of
the crack:  in my case it passed through the main RF trace, but it could go through
any part of the circuit, making either an open circuit or an intermittent or high
resistance connection.  If it goes through a transistor there probably isn't much
chance of repair, but that might cause a problem where only part of the transistor
is operating, etc.

So the first thing is to look for cracks in the ceramic.  If you find some, follow them
and see where it may have affected the circuit.

Note:  it is very difficult to solder on the ceramic because it is such a good conductor
of heat.  (Especially don't try holding it in your hand when you solder!)  I was able
to bridge the break with a small piece of wire and solder it on either side, and it
has been working for 15 years.
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