CT-30 CTCSS tone board build

This is a brief review and test of the CT-30 Tone PL Tone board by Repeater Builder.  W3KKC designed this board basically from the application note from the FX-465 tone chip.  The board comes in assembled and kit form with everything you need.  I opted to build it from a kit.  The W3HZU 53.97Mhz repeater will be using this board in conjunction with the new HAMVOIP AllStarLink controller that we'll be installing soon.

The build is straightforward and well documented.  Even the greenest aspiring repeater owner can put this together and start using it.

Here's the initial test of the board proving it operates correctly.

Here's a walk through of using the board for Tone Decoder operation.

Software Defined Radio - Another Use

Sometimes you have to make do with what you have.  That means using tools that we have on hand differently than they way they were intended.

For instance this weekend I had to do an alignment procedure on customer's older rig that had a master oscillator and secondary oscillator that were out of calibration.  The frequency counter in the workshop just didn't have the amplification required to pick up the low amplitude signals associated with those circuits.

It occurred to me that an SDR (Software Defined Receiver) has tremendous accuracy and ability to concentrate on a small bandwidth.  This seemed ideal.  So I hauled the laptop down to the workshop and connected a spare 'scope probe to the test point in the radio that needed the alignment.  I didn't even have to connect the antenna terminal to the scope probe.  I just wound the lead around a rubber-duck antenna on the SDR.  The signal coupling was good enough to pick up a distinct hump on the spectrum.

It was easy to zoom into the signal and see when the oscillator was right on target for calibration.  A little tweak on the calibration adjustment in the customer's rig and everything was back in tolerance.

There's no excuse for anyone to be without an SDR these days considering the price.  The next step will be to get more familiar with GNU RADIO.  Tools like this would allow a user to create more useful applications than just the standard SDR tuner.  Why not a service monitor?  Why not a deviation meter?

We will get one of our software developers on that right away....

73 and happy hacking...

Antenna Switch repair

Here we have a rather nasty coaxial antenna switch.  It seems to operate alright when the contacts actually make contact.  This switch gave us trouble on Field Day, and I'd like to keep it in the arsenal. 
This is something we can fix.

Taking the back off the switch the internals are clearly visible.  The nuts are soldered on, so a little de-soldering is needed to get them apart.

The concept is to re-enforce the contacts with some helper-springs behind it.  I made the helper springs out of some stainless steel.  It has a good spring quality to it and will help hold the contacts down.

The whole thing was then re-assembled with the springs pushing down on the contacts.  The nuts were tightened back up and some solder re-applied to keep them from loosening.