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Author Topic: IC-271H,IC-471H SSB SQL does not work  (Read 1684 times)
HG5AZR
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Posts: 0




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« on: May 26, 2013, 11:18:08 AM »

Hi all!

Problem:SSB SQL not work propely in my IC-471H.SQL circuit is same than IC-271H,E.

At IC-9A on pin1 voltage is 1.0V after same minutes 1.15V.
On pin 4(IC-9B) -9.31V after same minutes -9.41V.
Pin 2(IC-9A) is always higher than pin3 (pin2 is 1.37 pin 3 is 1.28) SQL open.
In my IC-471H difference between pin2 and 3 is 0.09V,to much.

Other problem SQL sometimes closed at 3 clock position but not suddenly,means open 2 clock,close at 3 clock.
I like sql closed at 9 clock,but not possible to set with R224.

If I rotete SQL pot right totally on front side,SQL alway open.
R224 ssb sql calibration pot,if this pot in totally left ,sql closed at 3 clock.


In my IC-271H where SSB SQL working fine:
I controlled normal difference between pin2 and pin3 of IC-9A is 0.03V.(pin 2 1.35V,pin3 1.32V if SQL open)
If SQL closed pin2 is higher than pin3,difference is around 0.03V.
SQL open and close suddenly at 10 clock position.
At pin 1 is 0.98V,pin 4 is -9.25V ,not changing.

Why is so much difference 0.09V between pin2 and 3 at ic-471H?

Thanks
Zoli
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KE3WD
Member

Posts: 5689




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« Reply #1 on: May 26, 2013, 02:29:51 PM »

Hi again, Zoli,

Before doing anything else, have you cleaned and lubed the Squelch Control? 

Deoxit or any other good electronics tuner cleaner/lubricant, into the control and rotate the control several times from pin to pin. 

These radios are getting rather old, and I've been run around in circles due to the potentiometers drying out.  Even if the control does not sound scratchy, the center wiper brush can sometimes create all sorts of problems, much like you describe.


73
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HG5AZR
Member

Posts: 0




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« Reply #2 on: May 26, 2013, 02:47:19 PM »


I measured but 500 ohm value is ok.,cleaned earlier.

Problem:SSB SQL doesnt work properly.
If I try to rotate SQL pot on front side but  SQL doesnt close.
IF I rotate R224 SSB  SQL calibration pot in radio totally left,SQL begin to work and on front side around 1 clock position SQL  is closed but after 2 minutes at 12 clock position closed,after 5 minutes 11 clock position,later at 10 clock.
SQL not suddenly closed, example:9  clock position opened and 11 clock position closed.
Sometimes :9  clock position opened and 3 clock position closed,sometimes never closed.
 
I realised that main problem that voltage on pin2 of IC-9A is always higher than pin 3,difference is around 0.07V.IF I set on front side SQL pot to right,voltage increase on pin 3 but also on pin2.
 
I have IC-271H ,same SQL circuit,working 100%, SQL closed suddenly: at 10 clock closed and open,I can calibrate with SSB SQL  R224 pot in radio if I like on front side SQL example at 8 clock or 10 or 3 clock close.

At 5-2 page is in ic-271H service manual how working ssb sql.
Any suggestion?

Thanks
          Zoli



 
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K9YLI
Member

Posts: 863




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« Reply #3 on: May 31, 2013, 08:33:37 AM »

 I checked and the 271 is an  all mode rig..
 I would just    adjust the  squelch  for the  FM   mode and foreget it..
 There is usually  enough  background noise on SSB mode  to keep the squelch  open all the time.    Only on FM  mode do signals  jump up above the noise to make squelch  usefull..



 I did not think anyone  used  squelch on SSB...
 I have squelch on my  yeasu   FT980 ,  but it is basically an  FM mode  function.

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