Series Three Episode Four - Building TenTec 1330 pt 1

Series Three Episode Four of the ICQ Podcast has been released. The latest news, your feedback, upcoming Events and Martin (M1MRB) discusses building the TenTec 1330.

  • Canadian PLT Report

  • 'Hams' communicate in Haiti

  • New Icom Receiver

  • Lightship houses radio exhibits

  • Chesterfield Rally cancellation

  • 70 MHz in USA?

  • Annobon Island DXpedition

  • WARC Century Club Formed

  • Rockets powered by RF

  • Sunspot Chart on the up

  • NI's first D-STAR 'hot spot'

  • 2M yagi performance table

Building TenTec 1330 - Part One

Once your TenTec arrives you realise you have made a good choice. The package was well packed for shipping by the UK suppler and arrived undamaged. On unpacking the shipping box you find the whole is contained within a large plastic bag. This means thing do not get lost during shipping.

On opening the large plastic bag you will find an A5 manual which has a number of sections. The main sections are:-

  • Reference

  • Assembly

  • Useful information

The Reference section covers the radio specification and parts list. There is also an overview of the various sections of the radio giving you a better understanding of how this Radio works.

The Assembly Section is split into eight phases. Each phase completes a section of the radio and concludes with a tests to confirm you work is correct.

The back page has useful information for all radio amateurs.

The bag also contains an A3 circuit diagram and component layouts. This is very useful when you start construction because you don't have to keep changing pages during construction.

Because this kit has been out some time component go out of stock, equivalents are supplied for some items. There are supplementary sheets outlining this information.

Getting started

Please read the manual before starting, this will save you time in the long run. I also made changes in pencil from supplementary sheets so that the information was in one place.

The first thing you need to do is to unpack the radio and do an inventory to insure you have all the parts before building.

The package before opening

The radio comes shrunk wrapped with all the components inside the case. Unwrap the case and using the Reference section of the manual perform an inventory sorting, components ready for building.

A view of the circuit and shrunk wrapped radio

Components sorted after completing the inventory

The small components sorted and layed out on some polystyrene

This will take you over an hour if done properly but this sections is like laying down the foundations.

At the end of each section you are given details of how to test your work. Sometimes you are given a number of different ways of achieving the same results depending on what equipment you own. If you have test equipment, use it. If not use the other options.

Phase 1: The Keying Circuit

This is probably the easiest part of this kit and very you should have no problems with this section.

This phase builds the RX/TX switching. Install components in the order they appear in the manual. Tick the manual after installing each component to ensure you don't miss any.

Testing is easy, just follow the instructions, test voltages and the keying circuit with a multi-meter

The Keying section

The Keying section built and ready for testing

Phase 2: Transceiver VFO

The construction and testing of the VFO is easily an evening project by it's self . Allow time to complete and test this phase and don't rush. This is the heart of the projects performance.

Install components in the order they appear in the manual. Tick the manual after installing each component to ensure you don't miss any. The manual explains how to wind the VFO toroid and you should have now problems completing this phase.


The frequencies for you VFO are listed on the circuit. If you have a frequency counter this will make like easier. The VFO is running all the time . If you don't have a frequency counter you can do this set up with another receiver and listen for the radiation from the VFO

The VFO should cover 50khz and on the 30 metre band this is the whole of the allocation.

When you are happy you have completed this set up you can then move on to the next Phase.

The VFO running under test

Phase 3: Transmitter Mixer and 10.1Mhz Bandpass Filter

Completion of this phase will give us a low-level transmit stage after the VFO. Once complete you will be able to hear the output on another radio in the 30 metre band.

Ther are not too many components in this phase and it can be completed in about 30 minutes. Take care when installing the mixer IC u4 (NE612) to get it the correct way round.

Phase 3 complete (Transmitter Mixer and 10.1Mhz Bandpass Filter)

Phase 4: Receiver IF Stages

14.31818 Mhz Receiver IF Stages

The Receiver IF is made with 4 * 14.31818 Mhz crystals configured as a four pole crystal filter. Care must be taken when constructing this phase because there is no testing procedure for this phase.