[Test-Equipment] Waveguide question

[Dave Brown]

Although waveguide to coax transitions are not difficult to make and 
adjust you may be better to just buy one, paticularly if you want to 
use it over the full range of your source/amplifier setup. You want an 
old HP X281A (or B) or similar. Other manufacturers did (and do) make 
them.   But the X281A is probably still fairly common. I have a couple 
here I use reasonably often.

The X281A has a type N female coax connector -the B suffix will have a 
stainless type N or maybe an APC-7 or ??--- I think they were special 
order versions. So assuming you want type N then stick with an A 
suffix  if you can't establish the connector type prior to purchase.
 I see an H281A on ebay just now- but thats for H band, not X. Beware 
the prefix!

Cheers
 Dave B, NZ





----- Original Message ----- 
From: "Scott Schappert" <sschappert at balboa-instruments.com>
To: <Test-Equipment at mailman.qth.net>
Sent: Saturday, January 21, 2006 5:54 AM
Subject: [Test-Equipment] Waveguide question


G'day to the list.

This may be slightly of-topic, but I have a question about coupling an
RF amplifier to a waveguide transition:

I have an 8-12 GHz solid state source to an 8-12 GHz wideband, solid
state 1 W amplifier.  I want to launch the RF directly from the output
of the amplifier to a WR90 waveguide transition.  All connections on
instruments are 50 Ohm "N" type connectors.

I am concerned for the amplifier because the Z-zero is 50 Ohms output
into the infinite Z-zero of the waveguide.  I have used other 
amplifiers
where the output is directly coupled to a waveguide flange, but never
tried it on my own.  I do not want to damage my amplifier from 
mis-match
on the output.

I would be very grateful to hear from someone who might be able to let
me know how to approach this situation intelligently.

Best regards to all,

-Scott






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