PA1JIM » Technical

Aligning a FT-817

PA1JIM — Tue, 04 May 2010 07:22:25 +0000

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

PA1JIM — Fri, 01 Jan 2010 19:49:06 +0000

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…

To install the option you need two things: a Kenwood TS-850 (or other Kenwood, but this article is about the 850) and this little ‘bug’ TCXO-SO-2.

First unbox the little bug and read the manual on how to install.

Then open your rig upper cover, be careful to disconnect the speaker cable as soon as you lift the upper cover. The speaker cable isn’t that long.

Unscrew the screws around the CAR-board on the left (enjoy my revised CAR-board

Lift up the CAR-board with the metal plate underneath. Now you’re in the oscillator department of your rig. Disconnect all cables from the oscillatorboard en unscrew. You can lift out the oscillatorboard.

Now gently solder the SO-2 into place and brake both jumpercables W1 and W2.

Your SO-2 is installed! Now build everything in as it came out and you can test your new installed option. Joerg supplied me with a neath little trick to check if the oscillator frequency is okay without a counter: tune on 10 or on 15 MHz. You can hear a signal. When you switch between USB and LSB the tone height must be the same on both USB and LSB. When it’s not you have to adjust the SO-2. You can do this adjustment by breaking the label on the SO-2. Right underneath the “K” from Kenwood there is hidden a little screw. With this screw you can adjust the bug.

After installing the tone height on mine sounded pretty okay to me. Listen for yourself, the file contains a one minute sound. Recorded on 15 MHz. Switching between USB and LSB every 5 seconds starting with USB.

If you want to build in this option, it is a piece of cake. Only the building out and building in of the oscillatorboard is taking the most of your time. Enjoy and good luck!

Voice Keyer part 3

PA1JIM — Tue, 30 Jun 2009 13:10:12 +0000

Okay, it took a while but I’ve finished the voice keyer project! The last article about this voice keyer I’d receive the wrong package. The second time I did receive the correct PCB but the programmed GAL-chip was a 20-pins one instead of a 16-pins. After receiving the correct GAL-chip there was another problem. When I put on the keyer, all the leds where on and when I pushed one of the buttons, the led went out. Exactly the other way around from what should be… Another good look at the circuit learned me that you never have to trust a part list on its own. Always double-check with the circuit before ordering parts. The 5 transistors in this keyer should be (according to the part list) the NPN BC547. But at the end the circuit told me otherwise: 4 of them should have been a PNP BC557.
So after re-ordering the new transistors, the keyer works great! The sound is good, the handling is just perfect! I’m really happy with the result. I don’t know if the casing in the pictures will be the final one. Maybe I build or buy something nicer. But for now it’s fine! The next contest I can relax and listen!

It is a really simple and cheap to build voice keyer. For something around 40 euros you’ve got it up and running (of course without casing).

I will write an article about this building project for our club site soon. There will be circuits and PCB-layouts attached. But first I have to get permission from the original designer. Will announce here when it’s published.

Digital Power & SWR meter

PA1JIM — Tue, 04 Nov 2008 12:46:31 +0000

Since I am a relative new amateur, I don’t yet own many devices where I can do measuring with. Of course I have a multimeter and some old analog CB swr meter. But I like to have a better equiped shack. When I take a look in the online shops or at the flea-markets, I’m shocked about prices for a good SWR-meter or a simple frequency counter!

It must be possible to find a good but cheaper solution, I figured and fired on my favorite browser. After a few minutes of surfing I did find this very interesting link:

Digital Power & SWR meter from OH2NLT.

After reading this article I’m very interesting in building this device. So I went on part hunt. Most of the parts are easy to buy but the display is very hard to get a hold on. The solution appeared very easy: just send an e-mail to Matti OH2MH and he did send me a display in about 2 days!

So now I need to collect the last parts and start building… I’ll keep you posted!