This is the Nautel Radio Section of
The Broadcast Archive

Maintained by:
Barry Mishkind - The Eclectic Engineer
Last Update 12/12/09

Ampfet Transmitters

The first transmitters delivered by Nautel, when they entered the broadcast field were custom units for the CBC and New Zealand. However, starting in 1982, with the Ampfet 10, Nautel shook up the broadcast industry with a solid-state product that was dependable, lightning resistant, and just plain worked. Station owners could hardly believe that they could install a transmitter and it would run and run and run, requiring virtually no maintenance. It was true - and the industry has never been the same. 

The name Ampfet refers to the MOSFET (Metal Oxide Silicone Field Effect Transistors) that were at the heart of the transmitter, replacing the tubes that had served as the Power Amplifier in every previous rig.

Ampfet 10 - (10 kW) 1982

Ampfet 10 

First unit to CJFX, NS. Still in service in NC.

Ampfet 5 - (5 kW) 1982

Ampfet 5 

First unit to Cook Islands, NZ. Still in service. 

Ampfet 1 - (1 kW) 1983

Ampfet 1 

First unit to WDCR, Dover, NH. Still in service.

The Ampfet 1 broke the traditional transmitter mold in several ways:
        1. No PA or Modulator tubes.
        2. The whole transmitter was barely three feet tall.
        3. Most stations had to build a table on which put the transmitter.
        4. The VSWR circuits were so good the transmitter could run into an open or short circuit without damage.

Its major drawback was the lack of redundancy. Modules were not hot-swappable, and the power supplies were 72 and 15 Volts, not easy to replace if something happened locally. In those days, it could take two days for parts!

Ampfet 2.5 - (2.5 kW) 1984

Ampfet 2.5 First unit to 1YX, NZ

Ampfet 10S - (5 kW) 1984

Ampfet 10S 

Ampfet 25 - (25 kW) 1985

Ampfet 25 
First unit to CKQR, Castlegar, BC. Still in service at CKWW.

Ampfet 50 - (50 kW) 1985

Ampfet 50  
First unit to CBA, Moncton, NB. 
At last report: still in service.
CKST, Vancouver BC


Thanks to Nautel for providing some of the information and pictures on this page.

Would you like to know more about  

Or, just need to get BACK TO THE MAIN PAGE?

Thanks for visiting ... I hope you find the site interesting!

Copyright 1993-2008, 2009  by Barry Mishkind. This material on this site should not be reproduced or reposted in whole or part without express approval.

It would be a kindness if you'd take a moment and let me know who you are and what interests you have. If you can share some information, or even a picture, that would be great! Just use the address below. Thanks. (Please note: Due to the huge amount of spam on the internet, it would be extremely helpful if you would use something like [Oldradio] in your subject line, so the filters don't get in the way.)

An important note about this resource:

We have used many sources, including FCC files, university lecturers, historical publications and more, and have tried to be as accurate as possible, not repeating many of the myths of the industry (such as the Uncle Don Story) nor histories "manufactured" by promotion departments. However, I am not perfect, and may well have overlooked something. If you do see an error or omission, please let me know.

The accuracy and expansion of this resource depend upon our SHARING our efforts.

        Barry Mishkind