Issues found when building a Ten-Tec 1320 QRP Rig
I built a Ten-Tec 1320 20 Meter QRP Transceiver in May and June of 2005.
I had a few issues building it, I hope my experience will make your experience
- The VFO coil is very touchy. It changes frequency very easily. I ended up
following some advice I got on the internet and hot-glued the toroid core down.
It is still touchy, so check the rig's frequency calibration often. It does not
seem to drift during operation, however.
- Instructions for the front panel installation are incomplete. I suppose the
writer thought this was all obvious, but hey, I'm mechanically challenged.
- It does not say which part is the front panel.
- It does not say which way it does (it goes flange backward).
- The only instructions are in the "optional" section, not before step 8-3
- Step 8-2 should be down before step 8-1
- The screw holes for the front subpanel and rear heatsink are sloted in the
main chassis, but all are at the end on the slot. This makes putting the screws
- Step 8-4 uses two 1/2 inch 4-40 screws. Step 7-22 also uses one 1/2 inch 4-40 screw.
The kit only includes two 1/2 inch 4-40 screws.
- Step 8-5: SO-239 connector with cable attached does NOT fit into the space
between the back panel and heatsink. I should have put it in earlier (or you
have to unsolder the cable).
- Step 8-18 should also connect the speaker, at least temporarily. Steps 8-20
to 24 all listen to the speaker, but it isn't hooked up.
- The speaker mounting plate fits over the speaker. It's almost the last step
and the speaker is already soldered to the headphone jack. I had to unsolder
the speaker wires to install it without pinching the wires.
- There is a very loud clicking/poping in the transmit sidetone. N5ESE says
to change C1 to 0.1 uF (I still have not tried that).
- There was a very slight hum modulation of the TX signal.
- When I tried the transmitter on my 20 Meter antenna, I heard a frying sound
from the radio. The 100 MHz scope showed significant half harmonic energy (every
other peak of the sinewave was much smaller)! N5ESE's mod to the PA output to
stabilize it did not completely work. I had to push the output RF tranformer
towards the output filter toroids to get stability. I assume this reduced input
to output coupling on the PA transistor.
- I reversed the cover so the speaker wires don't fall near the RF PA.
In spite of all my issues, the final product works pretty well. I only got
2 Watts output, but your mileage may vary. I still worked California, not bad
for 2 Watts on 20 meters with a ground plane vertical antenna. Just think how well
it would work with a six element Yagi.
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page last modified Jan. 30, 2006