I’ve been up to a bunch of fiddling lately and haven’t bothered to do an update here so for posterity’s sake…this is what I’ve been doing.

I’ve always been curious about repeater operations and recently got the opportunity to play with a 440 repeater a friend bought. Boy has this been an eye opener.

We started out with it on a 40’ home Rohn 25 tower and just wanted a low profile machine to cover the local township. Well, we couldn’t use it at a distance of just a few miles. So we found another tower location at 100’ and figured….”now we’ll be in business”. The 100’ spot at 20W output got us maybe 7 miles. Fast forward and we found some people who had a 275’ location and a decent amp and pre-amp as well. Now we’re cooking.

There is a lot of work behind having well balanced link system audio with repeater systems. A lot more than I realized. We’re in good shape now and it’s been an interesting learning experience for sure. The machine is now linked into five others and it’s a lot of fun having a nice wide coverage area.

So on to the IF tap on the TS-2000. What is it? Well, an IF tap brings out the intermediate frequency at the mixer level of a receiver so you can use it for external processing. In my case specifically it’s the 10.7MHz 2nd IF that I’m feeding into my QS1R SDR receiver.

This lets me tune using the Kenwood TS-2000 and use all the filtering benefits and spectrum display of my SDR. This also gives me 2m and 440 coverage via the SDR which I didn’t have before doing this mod. The SDR does 500Hz to 52MHz or so natively.

I used a kit that Andy made up WA5UP that makes it nice and easy. It’s a JFET buffer. The purpose of the add-on board is not only to tap in to bring the IF out, but to prevent any oscillated interference from my receiver from getting back into the HF rig.

The concept for this is hardly my own and I used the document that K4DSP produced that I have kicking around over here. Thanks to both of those guys for making this simple for me.

The whole thing worked out fairly smoothly. I had to bypass the output attenuation in the kit to get a strong enough signal for my receiver, but once I got that figured, things were working well. The TS-2000 shows me about 7kHz of spectrum above where I’m tuned on SSB and about 16kHz below where I’m tuned. This is far narrower than the QS1R generally shows me, but I can now see 2m and 440 on my panadapter and use all the SDR filtering for receive that I have available.

Basically this gives me yet another option as to how to use my SDR rig in the shack.

All in fun and I managed not to burn anything up with all the fiddling too.

blog comments powered by Disqus


23 January 2010