[time-nuts] Semi-OT: Hardware for WR-90 waveguide sections?

[shalimr9 at gmail.com]

Robert is obviously correct, however you would be very hard pressed to be able to measure the difference between shoulder screws and regular screws in practice, either through insertion loss, VSWR or power handling.

So much so that I have never seen shoulder screws used on rectangular waveguide, even on very high power and very low noise equipment. Double ridge waveguide is a different story.

I have seen occasional waveguide arcs on very high power equipment starting at the junction between components or sections of waveguide, but not sufficiently or often enough or consistently enough to be able to pin it to the use of regular screws. 

Maybe I have been doing it wrong all along :)
Thanks for the reminder!!!

Didier KO4BB

Sent from my Verizon Wireless BlackBerry

-----Original Message-----
From: "J. Forster" <jfor at quik.com>
Sender: time-nuts-bounces at febo.com
Date: Sun, 19 Sep 2010 03:50:07 
To: Discussion of precise time and frequency measurement<time-nuts at febo.com>
Reply-To: jfor at quik.com, Discussion of precise time and frequency measurement
	<time-nuts at febo.com>
Subject: Re: [time-nuts] Semi-OT: Hardware for WR-90 waveguide sections?

The shoulder screw is an interesting idea, but I've seen (and taken apart)
lots and lots of waveguide over the decades, including brand new stuff
from major manufacturers and mil contractors.  I've never seen a shoulder
screw used.

FWIW,

-John

=================



> Hi,
> Not strictly true. Material is not important apart from environmental
> (corrosion) issues, but that is not the only concern. WG-16 (British) / WR
> 90 flanges are not dowelled. They rely on the fastners for alignment. The
> correct fastners are 5/32" shoulder screws (0.1557" dia 6-32 thread). The
> precsion shoulder locates the flanges. 5/32" bolts (a bolt has a plain
> shank) are a good second choice but you will probably have to pack them
> with washers as the grip length won't match ;-) If you have to use screws,
> at least align two diagonal holes with 5/32" dowels while nipping up the
> first two screws.
>  
> Robert G8RPI.
>
>
> --- On Sun, 19/9/10, jimlux <jimlux at earthlink.net> wrote:
>
>
> From: jimlux <jimlux at earthlink.net>
> Subject: Re: [time-nuts] Semi-OT: Hardware for WR-90 waveguide sections?
> To: "Discussion of precise time and frequency measurement"
> <time-nuts at febo.com>
> Date: Sunday, 19 September, 2010, 4:13
>
>
> k6rtm at comcast.net wrote:
>> Not completely OT, as stable and accurate timebases are very useful in
>> microwave systems...
>> What's the proper hardware to use for connecting WR-90 (10GHz) waveguide
>> sections? I figure 8-32 brass or stainless, avoiding anything magnetic.
>>
>
> whatever fits through the holes in the flanges.
>
> #8 requires a 0.187 hole, #6 requires a 0.156, #4 is 0.125, #2 is 0.109
>
> One reference I have says WR90 has 0.169" holes, so that's #6 hardware.
>
> Whether it is magnetic or not doesn't make any difference.
>
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