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!

PA1JIM » TCXO

Installing TCXO-SO-2 in Kenwood TS-850