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  • brandon lind's Avatar
    Today, 05:23
    brandon lind replied to a thread Base Radios ICOM -725 - fault after storage in Icom
    Do you mean it works out of band, but not in band? That's really odd...
    1 replies | 39 view(s)
  • brandon lind's Avatar
    Today, 00:41
    brandon lind replied to a thread Mobile Radios Mic Pin-out Icom IC 735 in Icom
    I altered the picture you sent me in a photo editor to show the proper wiring and emailed it back. I tried to post the picture here but I am out of storage space on this forum (hoping the admins can help with that). Just be sure to have the positive side of the capacitor facing pin 1 (the cap - stripe facing the mic) or the capacitor will very rapidly turn into a bad version of a resistor and damage the dynamic mic's coil. EDIT: via email, it sounds like JTD's mic is working now. Aside from a desire to post the wiring, this issue is resolved.
    8 replies | 184 view(s)
  • brandon lind's Avatar
    Today, 00:21
    Is there a way for the admins to allow a bit more attachment storage on this site? If we post a schematic, picture or other useful thing, our 4 or 5MB limit is rapidly consumed. This means we must delete prior attachments before adding new ones and this kills the old thread attachments that others might find useful.
    0 replies | 57 view(s)
  • brandon lind's Avatar
    Yesterday, 15:45
    brandon lind replied to a thread Mobile Radios Mic Pin-out Icom IC 735 in Icom
    The problem with using wire colors and terms like that is that it creates the possibility for us to mislead you by accident. For example, audio could mean audio out or audio in, the radio's mic jack supports both. RX could mean a variety of things based on microphone. Some radios require an RX pin to be grounded for the receiver to function ,whereas some radios consider RX at the mic jack to be audio out for a speaker built into the mic. Either way, I doubt it means ground for the TX (PTT) switch. The way you to describe the situation leaves too much ambiguity. The difference between microphones is as follows. A dynamic mic is one that most closely resembles a speaker ~ it has a diaphragm, pickup coil and magnet... a speaker in reverse. A condenser microphone is essentially a large surface area capacitor with an external voltage applied between the plates. When pressure waves from sounds in the air hit one of the plates, the capacitance changes superimposing an ac voltage on the DC plate voltage. An...
    8 replies | 184 view(s)
  • MikeAlex's Avatar
    Yesterday, 13:05
    MikeAlex started a thread Base Radios ICOM -725 - fault after storage in Icom
    Hi, Recently powered up my trusty (it was) IC-725 after it has been in storage, at room temp. in my indoor shack, now I find that it is not functioning within the limits of the bands of Region One - Europe, CIS & Africa. After performing a full test (on dummy load)I see that it not functioning to either Region 2 or 3 either but transmitting over a broader range than the ham bands. My first thought was that the diode D5 was probably open circuit - this I recall was the mod known as the 'MARS mod' which has been around awhile. My rig has never been modified - I bought it new to UK spec. However D5 is perfect, tested in situ it shows a typical forward resistance of 435 ohm with a suitably high reverse. I know that manufacturers often used a diode matrix to determine the market destination of equipment and wonder if that is the case with the IC-725 or are the band settings pre-determined in the microprocessor. I note that there are three other diodes associated with the microprocessor and three blank spaces...
    1 replies | 39 view(s)
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