If you’ve been following my latests posts, you’ll know that during the last V-UHF contest I detected reduced output power on the 70cm band in my FT-817ND. The output power was only about 60% of the maximum 5W in SSB and CW, but in FM mode it reached 5W. This problem only happened on the 70cm band. On all the other bands, the radio reached 5W output power in every modes. After spending some time studying the service manual, I came to the conclusion that the problem was that TX gain in the UHF band was too low. This is a software calibration parameter, so, in the end, fixing this problem has been rather easy.
On last Saturday’s V-UHF contest I observed reduced output power on the 70cm band in my FT-817ND. I spent the next day poking inside the radio with the oscilloscope trying to see where the problem was. While doing this, at some point I completely lost output power in all bands. I found that the problem was that F1002, an SMD fuse, had gone open. Here I describe said fuse and the replacement procedure, which I found much easier than I thought.
The Hardrock-50 HF is a very nice kit for a 50W amateur HF amplifier covering the 160m through 6m bands. It supports interfacing with the FT-817. With the proper cable, the amplifier can be connected to the ACC jack on the FT-817 in order to do PTT keying and read the BAND DATA signal from the FT-817 to select the proper band in the amplifier’s low pass filter automatically. The connections required are shown in the Hardrock-50 Tech Site. Yesterday, I prepared the cable to interface my amplifier to my FT-817ND. However, I have found a problem in my amplifier that prevents automatic band switching from working properly. Apparently, this problem has been fixed in the newest units and can be fixed with an easy modification in the units which are affected.
Today I’ve been installing the G4HUP PAT kit on my FT-817ND transceiver. This kit is essentially a buffer amplifier that allows one to tap the IF of a transceiver, in order to send it to an SDR. Then, the SDR can be used as a panadapter. This kit is intended as an entry level SMD project and it can be fitted to many popular amateur radio transceivers. In fact, this has been my first SMD project, and I have found it quite easy to solder using the right tools and technique.