[amsat-bb] Measuring SMA relays at UHF

[Norm n3ykf]

Forgot to mention:

The procedure to recover real "length" of what you're trying to
measure is arcane. Due to it's zanity, I thought I'd post it.

Imaging a number line where you're located at Zero.

Ahead in a positive manner proceeds zero to +180. At +180, it changes
to -180 and decreases to 0. Thus completing 360 (two pi, whatever) of
datum.

When a negative number is seen reported by the coverted return loss
data, to get an actual length, the reader must determine how many
degrees it's passed +180. Add or subtract, depends on how you'd like
to play with the signs.

Then add that number to +180, assuming less than one cycle.

More than one cycle, add N times 2pi plus pi.

In human speak:Nx360+180+your result.

Given that number, start subtracting. Lets use an example from the
data I just posted.

Ex: https://www.flickr.com/photos/n3ykf/30182713518/in/dateposted/

Start with -97 (Marker 2, 436.8 MHz) and work your way back: 281.3 degrees.

NOWHERE is the procedure detailed. I found the clues over in the
programming manual.

What a way to spend a day.

Norm n3ykf
On Wed, Aug 15, 2018 at 10:47 AM Norm n3ykf <normanlizeth at gmail.com> wrote:
>
> Hi all!
>
> Playing with my toys, trying to create a CP 10x2 UHF antenna
>
> Using an Anritsu S113b which does not have direct voltmeter readout.
> These numbers were calculated by making a return loss measurement and
> converting it to relative phase with their Line sweep tools software.
>
> Converted data here:https://www.flickr.com/photos/n3ykf/
>
> I have a Times T-100, using a similar procedure, very similar, almost
> identical numbers were returned.
>
> Setup: S113b has an N female. To make SMA, I added an  N male to male,
> then a N female to SMA female.
>
> Used a calibrated SMA OSL kit.
>
> Test pieces: two Transco SMA 24V relays and an SMA jumper, consisting of two
> elbows and some straight pieces.
>
> Coax to be used in final device is RG-142B/U. (El Cheapo on the bay)
>
> Did use a 5/16 wrench to snug up all the connections.
>
> First order of business was to calibrate all the test gear. Noting how
> long the adapters attached to the N connector were as well as noting
> the length of the test cable.
>
> Got some interesting results:
>
> RYA NC: 232.2 degrees
>
> RYA NO 231.8 """"""
>
> RYB NC 231.3""""""""""
>
> RYB NO 231.0 """"""""""
>
> SMA jumper to connect Common->NC to NC->common 281.3 degrees.
>
> Does this look correct? How does such a small package contain such a
> lengthy RF path?
>
> I went through this whole process (took about 5 times longer) prior to
> my trip to 5J0 and realized that mistakes had been made. Skipped the
> CP attempt, Took the pair of crossed linear 10 elements, diddled by a
> Tohtsu spdt 12v instead
> Worked like a charm from AOS to 5-7 degrees above the horizon so that
> I could switch polarities. What a blast. Used my homebrew rotator.
>
> https://www.youtube.com/watch?v=1sDP6lAiWGw
>
> Please ignore my 2yo little monsters. They can and do make s9+ noise.
>
> Trying to get the coax for a cp antenna correct this time. Waste no more coax..
>
> Currently in the field. I'm wondering if there's something inside the
> relays making them look longer. Coax seems to be realistic lengthwise.
> SMA jumper is maybe 6cm long. Measures slightly longer than 3/4
> Lambda, though.... Will make some measurements to a test article,
> disassembly and photos.  Stand by, pussycat!!
>
> Norm n3ykf