TenTec 1320 QRP Rig Thoughts

When I read something in print or on the internet I generally take it with a grain of salt. When somebody says that this or that is either wonderful or terrible, I try to keep in mind that it is, after all, somebody's opinion. So take whatever I say with a grain of salt please.

I purchased the TenTec 1320 rig a little over two years ago just prior to the first Flight of the Bumblebees. My wife Karen (AB4VE) and I drove up to Seveirville one Friday, toured the factory and afterwards happily departed with a couple of small T-Kits and the 1320.

I stayed up for several of the following nights assembling my new kit. The first thing I did was inventory the parts. The quality of the parts and the pc board is excellent. I was missing one non-critical capacitor (quickly supplied by TenTec). The manual is pretty good but I would have preferred a larger format (8-1/2 X 11). All the T-Kits seem to use the same small manual layout including the 2-Meter kit I built. Someone has pointed out that complete alignment instructions are scattered throughout the entire manual. One page in the back containing that information would be helpful.  Included with the manual was a page of corrections, most of which did not apply to me since I had the newer board (The original boards used in the TenTec QRP rigs did not use plated thru holes). The large schematic on a separate sheet was very difficult to read and requires a magnifying glass of some sort.  At each stage of assembly I performed the tests and was rewarded each time with success... with one exception. After winding L3 the frequency would, with barely a bump, jump 400 kHz up or maybe 400 kHz or so down. It was difficult (it seemed impossible) to tell if I was going to be in the ballpark once I glued the toroid to the board. Even after final assembly I rewound that coil 4 or 5 times. Still the frequency was all over the place. Unfortunately, I ran out of time to get the rig ready for the Bumblebee event and put the 1320 on a shelf for a later time. That later time turned out to be 2 years later (about 3 weeks ago). Recently I received my K2 and decided that there was no way I could start it until I resolved the 1320 problems. How could I start on the sophisticated K2 when the little (seemingly simple) TenTec rig had bamboozled me. I was determined! I was out of the specified #28 enamel wire but had plenty of #26. After again rewinding L3 about 4 more times to get the leads to come out right and still give me some ability to either compress or expand the windings I wound up with 1 fewer turn than specified. I glued the toroid to the board with some silicone (non-corrosive Dow-Corning 3145 - I think that's the number). After it cured, I took some clear nail polish and coated one-half of the windings. When the polish dried I was able to get the VFO coverage set at 14.001 up to above 14.060; not bad. Next I coated the remaining windings with the clear nail polish. After it dried and after adjusting L14 the coverage was from 13.997 up to about 14.066. A 10-turn pot would be a helpful addition.

The first two calls to two DX stations calling CQ resulted in two contacts.  It puts out about 2 watts when using a 12 V Gel-cell. I didn't check the power when using a higher voltage. I'm still not so sure the QSK is what it should be. The AGC doesn't seem quite right either. I actually prefer the way the receiver sounds on my Small Wonder Labs (non-AGC) SW80 rig. I haven't really tested the VFO yet for stability over time. It appears that about 30 minutes is required for
things to settle down. The winding of some of the toroids seems kind of unconventional. Placing windings over 25% or less of the core rather than 60% or more just didn't seem an ideal approach. But I'm not an engineer. The case is certainly rugged. Taking the pc board out for repair is a little aggravating.

I know it shouldn't have been so hard to get on frequency... but it was. I just don't quite know why.  I'll try to add a complete review here once I get it tweaked.

I have made enlargements of each section of the 1320 PC board.
If you would like to view any of 8 different sections start by clicking on the image below.