| Author |
Message |
    
Ikei
New member
Username: Ikei
Post Number: 2
Registered: 3-2007
| | Posted on Friday, March 16, 2007 - 12:54 am: | 
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Might sound like an funny concern, but...
I just got my Magnum S-980 from Copper. Hooked up to power/swr meter and antenna. Hears fine, but..
All my other radios, Kenwood, Cobra, Uniden and good old J.C. Penny, when you unplug the mic, the rcvr cuts out. I know according to the schematics in the other radios, the rcv circuit is protected from xmit by the switch in the mic. The switch in the mic cuts out the receiver while xmitting. The Magnum S-9 rcvr is on when the mic is out. Can't follow much in the mic audio because the echo board does'nt show what's happening there. How is the rcvr protected from the xmit side? I havn't keyed up yet until I can understand what's going on in the circuit. Never seen a schematic that has so many circuits leaving and entering as many times as the Magunm. Sure isn't a good old USAF T.O.
Thanks |
Tech237
Moderator
Username: Tech237
Post Number: 723
Registered: 4-2004
| | Posted on Friday, March 16, 2007 - 8:42 am: |
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It is most likely internally switched during transmit using diodes or transistors. Most radios use the same amplifier for received audio as they use for the mic amp.
Remember most of the other radios you mention are older non-cpu style radios adn therefore based on old technology.
Simon
Tech237
KD7IEB
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Tech833
Moderator
Username: Tech833
Post Number: 1625
Registered: 8-2002
| | Posted on Friday, March 16, 2007 - 10:57 am: |
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Let's go even further back in time to the tube days. ALL radios would receive without a mic plugged in! Relay switching, never fails. Almost. |
Tech237
Moderator
Username: Tech237
Post Number: 724
Registered: 4-2004
| | Posted on Friday, March 16, 2007 - 6:45 pm: |
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Tech 833,
Tell that to my FT-227RH. Grin. A solid state relay is starting to look good.
Simon
Tech237
KD7IEB
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Tech833
Moderator
Username: Tech833
Post Number: 1627
Registered: 8-2002
| | Posted on Saturday, March 17, 2007 - 10:52 am: |
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Sounds like someone underengineered the relay requirements in your radio. Tima to re-engineer. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2457
Registered: 9-2004
| | Posted on Saturday, March 17, 2007 - 11:18 pm: |
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ikei,
your radio is supposed to be like this.
yes, the past generation of solid state radios all cut the receiver audio out when the mic was unplugged.
these new radios are designed to leave it on even if no mic is plugged in.
nothing wrong, just a new convenience.
later,
matt
anyone wanting a "clean signal", just look to the left and build one of these!!!
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Tech237
Moderator
Username: Tech237
Post Number: 725
Registered: 4-2004
| | Posted on Sunday, March 18, 2007 - 9:16 am: |
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Paul, you are right. A look at the FT227 group on Yahoo shows that this is a common problem. The symptoms of which are 1) some times no tx but tx lits up, 2) some times no tx and no lights, some times it tx after a delay and 4- rarely - it works correctly.
Simon
Tech237
KD7IEB
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