A Tentec 1420 for fieldday use


From time to time I like to take some ham gear out in the field, and call it a one-person-fieldday. As a setup I typically use a fishing pole that holds a 20m vertical with some radials, a manual MFJ tuner and a Tentec 1420 homebuild (kit) transceiver. As a power source I use a 12 Volt gel battery. The pictures below give a rough idea of what the entire setup looks like. As you can see I can take the entire setup with me in a backpack for a bikeride.

Aligning the Tentec 1420

As the settings of the Tentec 1420 were set a long time ago, with limited equipment, I recently decided to redo the alignment of this transceiver. Part of this alignment was to get the pitch of the morse signal during sending to 700Hz which I've got used to with my Yaesu FT-950 at home.

The procedure used for this alignment is given below (derived from the TenTec 1420 kit manual), as it may help others going through the same procedure. The transceiver is designed to operate from 13.8 volts DC for maximum output and receiver volume. When designing battery packs for portable operation, be mindful that “slightly” lower voltages (such a s 11-12 Volt) will result in considerable reduction in RF output.

  1. Measure power consumption
  2. Align RIT control to make sure VFO operates at the same frequency at Receive and Transmit
  3. Side tone pitch. To make sure you are transmitting on the same frequency as stations you are hearing, L14 must be adjusted using a reference signal which can be heard on both the Model 1420 reeiver and a second receiver. The reference signal can be actual 20 meter CW activity or a source such as an RF signal generator. In my case I've used an ancient Advance B4A signal generator, which took a warming up period of 1 hour before it was stable enough to to this measurement.
  4. General Receiver alignment
  5. Transmitter Power check
  6. Sidetone Adjustment

The pictures below indicate my setup for measuring, while the paint tin contains a dummy load and some cooling oil (paraffine) to absorb the produced RF energy.

40 Volt peak-peak into 50 ohm, appears to be exactly 4 Watt. After all the alignments were done, I've created a new table that cross reference the frequency dial reading with the actual frequency in use.

dail frequency (MHz)
1 13.997
2 14.007
3 14.031
4 14.038
5 14.045
6 14.052
6.5 14.055
7 14.057
7.5 14.060
8 14.063
9 14.068
10 14.071

As an end result I consider my Tentec transceiver much more fun to work with, and I'm still impressed by the quality of this product (which is still available for sale, 2015).