Wednesday, 17 December, 2003

Firing up the Collins

I spent some time over the weekend fiddling with my Collins 75A-4 amateur radio receiver (see March 12, 2003), making sure it fired up okay and trying to get familiar with the controls.  Since Jeff Duntemann (K7JPD) had it working a year ago, I figured it'd come up with little trouble.  Even so, this old gear can be temperamental if it's unused for a while so I borrowed a Variac from a helpful member (Steve, KI5YG) of the Williamson County Amateur Radio Club and brought it up slowly.  I dug in the closet for my old flying headset, attached a too-short piece of lamp cord for an antenna, and was able to receive a few signals.  I need to attach a better antenna, preferably running outside or stretched in the attic, and then go through the calibration and tuning process to make sure the radio is functioning perfectly.

A bigger problem is that somebody apparently modified the radio years ago to receive military communications.  The 15-meter and 11-meter bands, and half of the 10-meter band have been hijacked.  The long-term project for this rig is to remove the modifications and put it back to original working condition.  I need to improve my soldering and schematic-reading skills before I tackle that one, though.  There's also a BNC antenna connector on the back that I think was an after-purchase modification.  I rather prefer that kind of connector, so I'll probably just leave it the way it is.

I'm fortunate in that I have the original manual for the receiver, including good documentation for the modifications.  That old manual is getting pretty ragged, though.  A search of the Web of infinite delight revealed the Collins Collectors Association which has, among other wondrous things, the full 75A-4 receiver manual in PDF format.  Time to download and print that, then put the original manual in a ziplock bag.