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

ernieperes at aol.com ernieperes at aol.com
Sun Sep 19 13:34:17 UTC 2010


Hi,
 In many military Russian locator and other eqmnt, also from the east block microwave units/chain used the shoulder screw to have perfect alignment between wave guides...
I was the same with the  Czech Republic  radars too.....
I have been operated many above mentioned units.........
Rgds Ernie.





-----Original Message-----
From: shalimr9 at gmail.com
To: Time-Nuts <time-nuts at febo.com>
Sent: Sun, Sep 19, 2010 2:49 pm
Subject: Re: [time-nuts] Semi-OT: Hardware for WR-90 waveguide sections?


Robert is obviously correct, however you would be very hard pressed to be able 
o measure the difference between shoulder screws and regular screws in 
ractice, either through insertion loss, VSWR or power handling.
So much so that I have never seen shoulder screws used on rectangular waveguide, 
ven on very high power and very low noise equipment. Double ridge waveguide is 
 different story.
I have seen occasional waveguide arcs on very high power equipment starting at 
he junction between components or sections of waveguide, but not sufficiently 
r often enough or consistently enough to be able to pin it to the use of 
egular screws. 
Maybe I have been doing it wrong all along :)
hanks for the reminder!!!
Didier KO4BB
Sent from my Verizon Wireless BlackBerry
-----Original Message-----
rom: "J. Forster" <jfor at quik.com>
ender: time-nuts-bounces at febo.com
ate: Sun, 19 Sep 2010 03:50:07 
o: Discussion of precise time and frequency measurement<time-nuts at febo.com>
eply-To: jfor at quik.com, Discussion of precise time and frequency measurement
   <time-nuts at febo.com>
ubject: 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)
ots and lots of waveguide over the decades, including brand new stuff
rom major manufacturers and mil contractors.  I've never seen a shoulder
crew 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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