Ten Tec 1320

The Ten Tec 1320 is a 14 MHz (20m) CW transceiver. It covers about 60 kHz of the band you choose from 14.000 to 14.150 MHz (this is set by the winding of the tuning inductor). The RF power output is 3-4 Watts so it's a QRP rig and good fun to build and operate, a really good introduction to building and operating.
This is a very poor picture but you get the idea...
I have now sold the 1320 to pay for the HB-1A but I did like it - analogue is much nicer than digital!

I won't do a review of the build or list modifications here, you can see those on many excellent sites of the internet. What I will do is try to give an overview of what I think of the kit and whether it is worth the money.
I've looked at many QRP (low power) kit offerings and the Ten Tec 1300 range are very popular with some people making complete stations from buying all the models in the range. Some people may want a multiband rig - this is not the kit your you - and to be honest I think it is worth sticking to the one band for a start. I would probably have gone for the 40m (1340) - 7MHz version in hindset as the band is open a lot more then 20m [sunspot minimum]!
The kit is all good quality (PCB, components, case etc.) and the instructions are very good. They could do with updating and better presentation in line with other suppliers but I found them to be easy to follow for the build stages. There are suggestions on other sites on torroid winding which are worth reading but these are the things I would advise a builder to consider:
  1. Make sure you add a fuse and idiot diode to the power leads - during construction there is plenty of opportunity for error and you should protect your investment
  2. Have a really good desoldering tool - an electric desolder pump (Maplin N37CH £12.99) is a great addition to your tools and is actually needed! It's suggested you solder some spare wire onto the board then tack L3 onto them to get the tuning correct. Removing those wires is a real pain but with a proper desolder tool it is easy.
  3. Get a hot-melt glue gun to hold the coils firm when completed.
  4. Read the mods suggested by N5ESE first and do them! The kit is no good without them.
When completed and aligned there are three things you must do.
  1. Replace the phono sockets for external connections and replace them with a proper power socket and plug and a proper mono 3.5 mm socket for the key.
  2. Put an 'idiot' diode in the power supply line (if you haven't already), whilst you now have a good power connector, get it wrong at the battery and it will be smoking!
  3. You must carry out the Audio modification suggested by N5ESE, it is essential to stop the hiss from the LM386 adio amplifier chip and makes a huge difference. Also the change of C1 value to 0.1uF
Once that is done you are ready to use the rig:
  • The receiver is very sensitive and selectivity is pretty good with a 4-pole crystal filter, a simple 600 Hz audio filter might help buyr is not really needed.
  • Tuning takes a bit of getting used to after using a rig where you can adjust tuning rates but that's part of the fun and very simple after a while.
  • One of the big 'Wows' for me was the full break-in (QSK) so I can receive whilst sending CW (It switches to receive between sending the dahs and dits but it's so fast it feels like you are receiving all the time). On my IC 718 this is controlled by relays, which are quite noisy, but at this low power level it's all done with diode switching and is excellent. If you haven't used break-in before it's a revelation and well worth having.
  • Volume is good
  • The sidetone is a little bit of a concern, the frequency 'ramps up' for each key and you don't get the on/off sidetone we are all used to so I'll have to look into that to make sure I'm transmitting a clean signal.
Some ideas:
As the case is so large I reckon I could add:
  • An internal PicoKeyer
  • An internal ATU with absorbative SWR indication or even a power/swr meter
  • Frequency meter
  • Remove the speaker and add a battery pack like others have
All for another day
As an aside - This was purchased quite a while ago and built in a day. It never worked on transmit and all efforts to fix it failed so it went on the side for over a year! Like many kit builders, I learnt a great deal from trying to repair it - the biggest lesson was to check your test kit! I eventually found that it wasn't the 1320 at fault at all. The lead I had to connect it to the dummy load and power meter had an intermittent short and it was one of those things that it only shorted when I keyed the Rig, it blew the PA, I tested everything and all readings were fine, replace the PA and again it would fail.
After all this time fault finding and testing I have written some guidance on alignment as I am fed-up of thumbing between pages of the manual to align it, feel free to download from below and let me know if there are any problems or corrections.
Good kit for the price. Lots of space for future expansion and experimentation - isn't that what it's all about?!

More on the Sidetone

I've added files of the QUCS simulation of the TX/RX switching and images of the output of the switching are shown below. The Blue trace is the receiver (R) supply line to the IF mixer and the Red is the T line which feeds the RIT and IF Mixer mute (Td and the TX mixer supply follow T very closely).

There is a 10ms delay between TX off and RX on but the value of C1 does not allow the TX to fully switch off before the receiver kicks in. 

As you can see with C1 at 4.7uF the TX is still winding down when the Receiver is full on - one almighty overload and horrible sidetone at 'key-up'.

Reducing C1 to 1 uF makes a large difference in the simulation - no TX when RX is switched on.

And reducing to 0.1 uF makes a larger difference but this may affect the output waveform too severely.

Martyn Jones,
27 Nov 2009, 07:09
Martyn Jones,
1 Oct 2010, 03:13
Martyn Jones,
1 Oct 2010, 03:13
Martyn Jones,
27 Nov 2009, 07:09
Martyn Jones,
27 Nov 2009, 07:08