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Radio Question for Mark Bitterlich

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tamara_b(at)telus.net
Guest

Posted: Mon May 07, 2007 1:15 am Post subject: Radio Question for Mark Bitterlich

Hi Mark,

  

 first of all I would like to thank you  very

 much for all your valuable contributions  

 on this list.

  

 Thanks to you my hangar neighbor up

 here in Western Canada (won't the rain

 ever stop) gets his electrical problems 

 solved and doesn't get rid of his Yak  52.

  

 Since last week his PTT button on his

 original radio doesn't work any  longer.

 All the wiring seems to be fine and  the

 switches are working.

  

 I could be wrong but I remember that you  

 mentioned that problem once and you suggested 

 to have have the transistor in the radio  replaced

 what pulls the PTT to ground.

  

 Your opinion and help is always much  appreciated.

  

 Thank you in advance.

  

 Regards

  

 Elmar (C-FTKL)

   [quote][b]

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mark.bitterlich(at)navy.m
Guest

Posted: Mon May 07, 2007 1:28 pm Post subject: Radio Question for Mark Bitterlich

Thanks for you kind remarks Elmar.  I was not the one who mentioned

exactly what transistor might be bad.  In fact, I could probably figure

that one out with some time and study of the Russian Schematics, but I

do not have it off the top of my head.  What you might do right now is

to find out whether there is a VOLTAGE on the PTT switches in the

cockpit.  The RADIO supplies a voltage that goes out to the PTT

switches.  The PTT switch itself pulls that voltage to ground when you

close the switch.  This is what causes the radio to transmit.  If you

read the wires going to the switch with the radio turned on, you should

have GROUND on one wire, and a voltage on the other.  If that voltage IS

THERE, then something other than the transistor that you mention is bad.

Mark

 



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dsavarese(at)elmore.rr.co
Guest

Posted: Mon May 07, 2007 2:20 pm Post subject: Radio Question for Mark Bitterlich

I've been looking through the Yak 52 schematics and found the VHF PTT switch 

applies a ground to relay P116 in the Sound Warning Box.  In other words, 

when you press the PTT switch you should hear the relay click on in the 

Sound Warning box, which is at your right elbow in the front cockpit.  P116 

contacts which are closed by pressing the VHF PTT switch, go to the Intercom 

Amplifier (SPU).

Dennis



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mark.bitterlich(at)navy.m
Guest

Posted: Mon May 07, 2007 2:46 pm Post subject: Radio Question for Mark Bitterlich

Yeah, what he said.  Never trust what someone tells you who doesn't own

one.  I don't own a YAK-52.  I do own a YAK-50 which of course does not

have an intercom or a Balken -5 radio!    You can however open the

canopy and yell at anyone you want to.    



That said, you have a good line of troubleshooting to start with, thanks

to Dennis.  If you do not hear the click that Dennis is talking about,

once again... Go to the PTT switch and check for voltage on one wire and

a ground on the other.  If there is no voltage, it is likely that the

P116 relay coil is bad.  If there is voltage and there is a "click" ask

Dennis to look up what in the SPU ends up sending the ground over to the

radio's actual PTT line.  My guess is that the wire goes straight

through the SPU to the Balken -5 R/T itself.  



Another point of fact... Even if you hear the relay CLICK in the Sound

Warning Box that Dennis mentions, that does not mean it is good.  On

every relay I have seen that has failed in a Russian product, the relay

coil itself worked just fine (meaning that it made the CLICK noise).

What failed were the relay contacts themselves.  What this would then

mean is that you would have to open up the Sound Warning Box, locate the

relay that clicks, then figure out the wiring arrangement on the relay

based on the diagram that is printed on the relay.  Note:  The Russian

28 volt relays are easily replaced by American made versions.   



Mark

 



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tamara_b(at)telus.net
Guest

Posted: Tue May 08, 2007 3:14 am Post subject: Radio Question for Mark Bitterlich

Hi Mark, hi Dennis,

  

 thank you very much for your valuable

 informations, you guys are great.

  

 I will forward your trouble shooting  guide

 to David (there are only 2 Yak 52 in  entire

 Canada) as soon as possible.

  

 I wil keep you posted.

  

 Regards

  

 Elmar (C-FTKL)

   [quote][b]

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tamara_b(at)telus.net
Guest

Posted: Tue May 08, 2007 3:18 am Post subject: Radio Question for Mark Bitterlich

Hi Mark, hi Dennis,

  

 thank you very much for your valuable

 informations, you guys are great.

  

 I will forward your trouble shooting  guide

 to David (there are only 2 Yak 52 in  entire

 Canada) as soon as possible.

  

 I wil keep you posted.

  

 Regards

  

 Elmar (C-FTKL)

   [quote][b]

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Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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