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Author Topic: Recommendations for a custom setup?  (Read 1148 times)

Posts: 2

« on: May 31, 2004, 12:01:18 PM »

Greetings. I searched the site and couldn't find the answers, so here is a new post -- any help would be most appreciated for this specialized application of a transmitter (or transceiver) for use in a cyclotron.

Which model?
Tube vs. transister (or some transition thereto)?
Auto-tuner built-in or aftermarket?
Anything else?

I'm building another custom cyclotron for laboratory application, and need to alternate the charge plates (Dees) with approximately 100W push-pull at either 21.2250 or 21.6500 MHZ (within the 14.1245m/15m and 13.8472m/13m bands respectively), or 19.5000 or 38.9000 MHz (15.3740m and 7.7076 m respectively).  However, no equip. is readily available on the latter two frequencies and they have subsequently been discarded as viable options.

The 21.2250 MHz appears to be the best option using readily available Ham equip. and allows me to use the largest Dee's with a relatively weaker magnetic field, so this is ideal. (Typical 28MHz will not work in this case due to magnet constraints.)

The unit is well shielded and no actual transmission over the airwaves occurs.

The Dees act as the "antenna" within the cyclotron, and in vacuum tend to act as a capacitor yielding high VWR (sometimes 3:1 or higher) for periods up to 1 minute.  I will tune the Dees with inductors and resistors to get it in the ballpark, but do need a durable auto. antenna tuner because the quantity of protons will result in the need for continuous tuning of the system.

The cyclotron is isolated from the system ground on a 12v center tapped system, so the xmtr needs to be run on DC (actually a bay of center tapped 6 volt batteries).

To recap, system needs are:
12 volt DC, run off center tapped batteries
xmt. 100W over SSB/CW
21.2250 MHz (14.1245 m)
durable - capable of brief large reflection
auto. antenna tuner
a 100W amplifier to accomodate my RF oscillator's low output.

My hunch says to get a tube based system (though probably with solid state tuning), or a completely tube based system if it can be coupled with an aftermarket auto. antenna tuner.  What about a low powered transmitter with a beefy amplifier?

On the straight amplifier application, I could also just use one of my RF oscillators (output 1w) if I could get an amplifier which worked on 21.2250 MHz and which could be modified to accomodate the oscillator's low output.  This is actually a more ideal setup since my oscillator is spot-on accurate.

cf. for more details if interested.

Many thanks for any advice/help offered.

M. Gray


Posts: 5882


« Reply #1 on: June 01, 2004, 10:25:59 AM »

Amplifier Research is the first source that comes to mind:

Alpha amplifiers used to make custom commercial stuff too, though I'm not sure if they do custom anymore:

Mark K5LXP
Albuquerque, NM

Posts: 2

« Reply #2 on: June 02, 2004, 10:49:24 AM »

Hi Mark, thanks for these. I looked 'em over & was pleased at the prospect -- until I saw the prices.

Small research budget may make such a purchase out of my range for now and the equipment will most likely need to be used.

I've been looking at the Kenwood TS 440SAT and TS930SAT, ~$400-500 sounds more like it, but wondered if they'd fit my application -- or if another would be better.

Your thoughts on this?

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