It used to sit in the corner of my desk, my Kenwood MC-60 microphone. Although it has a suburb audio it also has so much RFI which makes it useless. On my to-do-list: search the internet to fix this problem so I can use this nice mike.
Finally I found the easiest fix there is for the RFI-problem with the Kenwood MC-60! Open up the bottom plate and just solder a 10NF capacitor between the blue wire and on the connector which connects to the rig (see picture). And done you are! No more RFI. If only I had knew this issue was so easy to fix, I could have start use the MC-60 a long time ago!
Tag: Technical
Aligning a FT-817
My precious FT-817 still is lying around in the shack unable to transmit. I’ve studied the service manual and did some measuring around in it. Regular readers of my blog know that a while back suddenly my Yaesu broke down due to shortage. It seems like a capacitor on the voltage input blew and took something with it. I let the input fix by a local service shop but that alone cost me already 75 euro’s. So now the Yaesu is able to receive again, but still no transmit.
My intention is to fix that myself. The local repairman told me it’s probably due to blown finals that the rig isn’t transmitting. That would make me a member of the “Blown Finals Club”. But I’m not quite convinced by his story. When only the finals are blown, you should get a very faint signal as output. But there is absolutely no signal at all. Not even when I take another receiver and poke around with that antenna in the transmit line of the Yeasu, no signal at all. So maybe the oscillator or driver stage must be (also) broken to get this behavior.
This would be my very first big repair job, there for I’m not in possession of various measuring equipment. The only measuring device I have is a multimeter. That won’t bring me very far in this case. Fred, PA3YH has a Multimeter which can measure HF-signals. A RF-millivolt meter, such as referenced to in the service manual. But it has a maximum reading frequency of 100 KHz. The RF-millivolt meter reads like 2,6 volts AC on the output of the oscillator (the service manual says it should be 66mV). But the output signal from the oscillator has a frequency of 65.875 MHz. So it’s logical the meter is not reading the correct voltage.
Okay, so I don’t know if the output of oscillator is correct, but I DO know that the oscillator has output! So I guess now I should look to the first driver stage.
But I think I’ll look for someone with a good scope first. It’s easier to check all the checkpoints in the service manual and also check if they have the correct value.
If anyone has good tips on how to find the problem, let me know!
Installing TCXO-SO-2 in Kenwood TS-850
Some time ago I’ve bought the TCXO-SO-2 option (Temperature Compensated X-tal Oscillator) from Joerg, DL6IB. Although I was very pleased to have the option, I postponed the installing because I wanted to figure out a way to measure the stability improvement before and after installing. Since I don’t own (yet) a frequency counter, I didn’t know a way to check.
A few days ago Joerg again send me a message asking me if I already installed the option in my Kenwood TS-850. I was a little ashamed to reply I didn’t. Promised him and myself to do this as quickly as possible. At this new years day I’m a little tired anyway, didn’t feel like anymore work around the house. So I sat down and opened my TS-850. Before I started with installing, I googled around to find a story of installing this option. Didn’t find anything. Okay, it is a pretty simple install but it gives me confidences to read about it. Seems I have to post the first story about installing this option… Continue reading