Fusion Message Board

In this space, visitors are invited to post any comments, questions, or skeptical observations about Philo T. Farnsworth's contributions to the field of Nuclear Fusion research.

Subject: Re: Off subject: TWT (Travelling Wave Tube)
Date: Apr 17, 3:35 pm
Poster: Richard Hull

On Apr 17, 3:35 pm, Richard Hull wrote:

>A TWT (also called a TWTA (A=Amplifier) when combined with a matching power supply, as is usually the case) is, as Richard pointed out, a microwave amplifier. They are not always broad band, however (particularly the "coupled cavity" variety).

>Not too complex in theory, mind bendingly complex to make work in practice as everything interacts with everything. Typical NRE time to make a new design (from "stock" parts and designs in an existing tube) is probably >12 months.

Jim has given the idea of complexity and with that comes cost.

I have a couple of surplus, mint condition TWT's from hamfest buys. A third one was shot and I dismantled it over a period of a week or two. These pupies are a nightmare to factory align. I removed over 70 small, hand placed mini magnets along the length of the long glass helix tube after carefully de-potting the silicone compound which sealed the assembly up in a gold plated mount and assmbly housing. (SMA connections for ins and outs.) I can only igamine the pick, place, and test on the small magnets at the factory. I am sure many of the designers and techs who work on this stuff are in looney bins in a few years on th' job.

According to our resident physicist at NRL, these babies start in the low thousands of dollars and rise to the $50,000 per device range based on power and frequency. A micro power TWT is about $3500.

Richard Hull