RF Chain Details

This is the First Local Oscillator and IF Mixer. The POS-200 VCO is the large silver box on the right. Notice that I had forgotten to add an input RCA jack for the VCO control voltage coming from the timing base. I had to move the feedthrough capacitor almost all the way to the floor to make room for the added RCA jack. I ended up having to use solder wick and solder to build up the space between the two because the original hole now became the space between them.

I also forgot to put an output RCA for the VCO RF output sample, used by the Tracking Generator. Fortunately, the TG is just on the other side of the floor from this section, with a couple of inches of overlap. I put an RCA jack in the floor, and then per Wes, W7ZOI, carefully shielded it using a piece of brass tubing and some coax shield.

It was in putting this circuit board into its compartment that I realized that 1 inch is simply not enough clearance for the height of the RF chain enclosures. Were I to do it over again, I'd make it at least 1.5 and possibly 2 inches. Fortunately, I had found some right angle header pins at a local surplus store. I had to improvise in a couple of places, because of parts placement on the board. The VCO Sample header, for example, had to sit at an angle around the TUF-1 mixer, and just barely has clearance below the compartment cover. Also, note what I had to do with +15V and ground lines (OK, technically, there are enough places in contact with ground to have a good DC ground, but better to be safe than sorry). There was simply no room, so I ended up cutting the header in half and pointing one pin one way and the other the other way.