[Moon] How to build a Wave Guide high power dummy load?

[James Malone]

I guess a wave guide transition (WR-137 to Type N connector) then to a 50
ohm dummy load would work also .. 

also a horn with low gain might be a good load too ..  if you have access to
metal work. and don't mind the radiation  ;-)

Jim WA3LBI

-----Original Message-----
From: Moon [mailto:moon-bounces at moonbounce.info] On Behalf Of
charlie at sucklingfamily.free-online.co.uk
Sent: Sunday, March 12, 2017 3:05 PM
To: Anders, <anders at la8lf.com>
Cc: moon at moonbounce.info
Subject: Re: [Moon] How to build a Wave Guide high power dummy load?

Hi Anders

How much power do you want to dissipate?

Normally such loads have some kind of ferrite inside them, usually tapered
to get good impedance matching.

You will not be able to use the WR90 one unfortunately, as the WR90 is cut
off at 5.7GHz and will look like a pure reflection.

I have made loads (for 10 and 24GHz) by glueing lossy rubber to the
broadwall, but these don't handle more than a few watts (the rubber burns!).

I have seen references to making waveguide loads using water eg

http://www.microwavejournal.com/articles/5210-a-water-dielectric-load-assemb
ly-for-testing-radar-transmitters

It would be "fun" to make one - probably doesn't have to be a cone, just a
simple wedge.  You could flow water through it using a fish tank pump or
similar.

73

Charlie G3WDG


73

Charlie

> Hi all,
>
> I need to build a dummy load for my 6CM TWTA.  Reason I want to build 
> one myself is that I have not found any WR-137 high power dummy loads 
> on E-Bay that match my budget.
> Can somebody tell me what goes inside a wave guide to make it a dummy 
> load?
>
> As I have a WR-90 high power dummy load, I wonder if I can use it on 
> 6CM TWTA via a 30CM long wave guide transition with WR-137 termination 
> at one end and WR-90 termination at the other end?
> If possible, I would probably have to add some screws along one of the 
> wide sides of the wave guide transition to improve return loss?
>
> Or, maybe sombody here has a WR-137 High power dummy load for sale at 
> a reasonable price?
>
> 73, Anders LA8LF
> anders(at)LA8L.com
> _______________________________________________
> Moon mailing list
> Moon at moonbounce.info
> http://lists.moonbounce.info/listinfo/moon
>


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