This link explains that the resistor needs to be cut, good luck...Clint vk2acm

http://www.mods.dk/view.php?ArticleId=2782

You might want to give this link a try he has alot of homebrew projects on his site....73 de Clint vk2acm

http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=3666

Look at this link under the alinco section click on the manuals section you should find a service manual on the ems57 mic there it is a zipped file...Clint

http://www.mods.dk/

There seems to be a jumper onboard that enables you to change the input voltage, check out the link below

http://www.rys.nl/sec1223.htm

Does this happen with the microphone connected or not connected, just in case there is an issue with the microphone scan up and down buttons...Clint

Try this link, look under yaesu and go down to the md100abx it shows the pinouts....73 de Clint vk2acm

http://www.mods.dk/downloadmanual.php?File=MD-100A8X_Manual.pdf

Gabriel,
Does your radio have an inbuilt TTL converter,let me know as i dont know the layout of the ft747 check your user manual...Clint

Try this link it might help you make your own interface...Clint

http://planeta.terra.com.br/lazer/py4zbz/tutsstv23.htm

I normally use an optoisolator for solid state rigs to isolate the grounds from the radio and computer ground,as the other gentleman advised you using grid block keying method of using a reed relay is advisable.
Try this link below to get some examples of using a optoisolator then add a reed relay,i homebrewed one for a ts520 and it worked like a charm,let me know if you need any more information.

73 de Clint vk2acm

http://www.angelfire.com/oh3/k8be/cwkey.html

Look under manuals for Yaesu the ft 707 manual.zip is listed there...Clint

http://www.mods.dk/view.php?ListManuals=yaesu

Martin,
You might try this link below it has the schematic in the manuals section...73 de Clint VK2ACM

http://www.mods.dk/view.php?ListManuals=kenwood

Try some of these service notes i found on mods.dk it might point you in the right direction in finding the faulty device...Clint

http://www.mods.dk/view.php?ArticleId=735

Randy,
Try RF PARTS they have for alot less than you mentioned check out the link below...73 Clint

http://www.rfparts.com/mototran.html

Try this link below....73 de Clint vk2acm
Look under Icom then look under the manual section.

http://www.mods.dk/view.php?ListManuals=icom

73 de Clint vk2acm

I am not sure if this is the information your looking for try this link.

http://www.radiohound.com/d7zpinfo.htm