There are a few reports about the Kenwood TH F7E transceiver that stopped working off an external power source and also stopped charging the battery. The transceiver is working ok on the battery.
In my opinion, this is a consequence of an "bad design" made by Kenwood engineers. Why?
Please read the following scenario:
You are using an external antenna and an external power supply on TH F6. Your antenna ground is common with the ground (minus) from your power supply. This may be done from your grounding system or from an second transceiver using the same power supply, or jus by an accidental touch between the antenna’s shield and the case of your secondary transceiver.
Now, the best part: when you are using the external power supply jack on your TH F6 A, the transceiver’s connector internal switch will disconnect the battery’s minus from the transceiver’s ground. This way, the battery will remain in the charging circuit and the transceiver will be powered by the external charger/power supply.
Having the ground ALREADY connected to the transceiver (from the antenna’s shield), your toy will be powered from the external power supply BEFORE the battery is disconnected.
This way, momentary, the battery will be DIRECTLY connected on 12.0-16V, depending on the external voltage ;-) . It will eat A LOT more current from your power supply and the F2 Fuse will open.
Hopefully the battery is internal protected ;-).
When charging/using an external power supply, FIRST connect the jack to the transceiver, THEN plug the charger/power supply into the wall (this sequence is also described in the user manual, without telling WHY ;-) . When charged, first unplug the charger/power supply from the wall then unplug the power jack from your transceiver.
1) Send the transceiver to your local Kenwood service.
2) Send the transceiver to your local Kenwood service.
3) DO IT AT YOUR VERY OWN RISK !
Well, if you live in Guyana (like me) and don’t have a local Kenwood service, then you may fix the toy for your self ;-). You will need some $2000 soldering devices ;-). If you don’t, you may use your old soldering gun. I’ll not tell you how, you must have the proper skills. If not, find someone with. If can’t find, go to step 1).
Now get the schematics. Locate the F1 and F2 fuses in the C2 area. I do not have the PCB schematics, so you must find the fuses: The F1 fuse is located on the same face with the power jack, close to the plus (+) battery contact. Is having “F” on it (at least mine). On the other side of the PCB you will find the F2 fuse, close to the power jack connections. F2 is having the same dimensions like F1, but is having an “S” on it. This fuse must be open. If it is, replace it. I was unable to find one, so I just used a piece of 1.5cm of thin wire, which will do the job. I also used a soft pack from an CPU computer cooler, just to prevent the heated cupper to spread all over the transceiver in case of “huh, id did it again” :-( .
Good luck! Waiting for “I did the job” reports ;-)