[arm-allstar] RPi GPIO COS/PTT

[no1pc at yahoo.com]

Josh,

I kind of get the RF-in-shack issue, but we know about these things.  

My first exposure to RF-in-studio was with a new hand-built solid state recording studio board in a building adjacent to a local 1500w AM station/tower mid-70s.  The studio guys 'invented' their magic shielded ground line to the board to 'cool' it down. We've all learned a lot since.

I trust, as an 'EoC', the entire setup and environment you are in has all the requisite proper station ground and measures to keep RF out of the environment?  External to shack entrance panel and ground by-pass?  Home run grounding conductors from each gear item to a single ground node?  

Easy and necessary to address the basics, as the NEC and many electrical codes prescribe for structures with antenna systems.  http://www.no1pc.org/radio/groundref.htm

Most of the Pi/whatever dongle/wall wart constructs are wholly neglected as high-impedance/floating victims of local RF.

The ONLY thing that sets off/confuses USB or similar in my shack now are the poorly engineered "Chinese comb generators".   My BF-888 porta-node began with re-packaging that little noise box in a solid aluminum shell, shielded everything in and out. 


   2. Re: RPi GPIO COS/PTT (Josh W4ZZK)

Message: 2
Date: Wed, 25 Jan 2017 11:33:19 -0600
From: Josh W4ZZK <w4zzkjosh at gmail.com>
To: ARM Allstar <arm-allstar at hamvoip.org>
Subject: Re: [arm-allstar] RPi GPIO COS/PTT
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    <CABKLMaNA7OuN2tpByjjTAA1GPDfxoxV4FkOv7jaYAsYbAKEU3g at mail.gmail.com>
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Just a note about the Behringer UCA222
I'm an Audio Engineer and Production Manager in AL/MS/TN market, and
have "played" with these little boxes for several years.  The newer
222's are quite better in manufacturing than the older ones.  Hard to
believe, but since Behringer had been bought up by Music Group, their
QC has went up some in this device's pro-sumer market... even by leaps
and bounds in the commercial/professional sector.

Do note that these 222 boxes are VERY susceptible to RFI. For example,
I attempted to use it as a "receiving" sound card for a few Online
Streams at a local EMA office.... typical install scenario....
computer, radios, and this box all were in a rather active RF
environment. (HF VHF and UHF).  I don't know if I simply had a unique
scenario on my hands, but there would be some times where it would
"lose sync" with the computer, like I had disconnected the USB cable.
That meant restarting the streaming app to regain sync.  Remoting in
to the PC again and again to resync the device got old pretty quickly.
Perhaps there were more RFI choking and eliminating I could have done,
but I exhausted all feasible, and "affordable" options before going
with individual $3 CM108 Cards, which work GREAT.  Maybe some way to
bleed off transient voltage from active RF environments would work...
I don't know.  But, in their normal operation, the little 222 boxes
are halfway decent. Very simple audio interface. Would love to see a
schematic of it, and know how we could go in the future with using
that box.

Josh Hatton W4ZZK
Muscle Shoals, AL
w4zzkjosh at gmail.com