Friday, August 21, 2015

Kenwood TM-D710 reboots at transmit/deaf possible fix!

The D710 was the radio I bought when I got my Tech license in the fall of ' it is about 6 years old.

I haven't really had any trouble with it, but starting a year or two ago on VHF at High power the radio would reset/reboot when I keyed up.  If I lowered the power to Medium then it would not reboot (I assumed some sort of low voltage condition).  More recently I noticed that it was getting deafer, unable to hear repeaters that should be in range.

I probably wouldn't have done anything, but I found a couple of websites describing a design flaw of this radio (and maybe it's sister the D700) having to do with some filters.

Here are the links I found.

I ordered mine from PacParts for $25 with shipping.

I followed the directions on the previous links on how to disassemble the radio but I didn't feel comfortable attempting to disconnect the center antenna pin from the main board...luckily all I had to do was rotate it 90deg and I could access both sides of the board to remove and replace the filters.

Note, my mainboard had the filter name silkscreened to the board to make it harder to put the wrong filter in.  Also note, the actual filter name is only the 50G, 50E, 55G, and 55E...the part number on the replacement makes it a bit more confusing than it needs to be, but not difficult.  I have the vacuum powered desoldering system, so removing the filters (5 tiny pins) was not difficult.

Fast forward.  I got it all back together and tested a local VHF repeater using High power, worked fine and radio did not reboot.  I did not get a chance to test the UHF part until I drove home from a radio meeting last night.  I had the radio scanning the 'local' repeaters for my drive and I picked one up that sounded clear so I joined in the middle of a net checking...oops I had not heard the net part.  But they kindly gave me a signal check and said audio was clear but a bit scratchy...then after I told them my position they told me I was 65 miles from the repeater, and due to the terrain, not line of sight...So apparently the UHF is fine, and also the propagation was good last night.

If you have an older radio, and any symptoms like I listed, I would swap out those filters.

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