Maximizing the Art of Experimentation: Part 3

My involvement w/Amateur Radio has always involved experimentation, from refurbishing an
early 50's Heathkit AT-1 transmitter (at 7.5w), achieving Worked All Continents (WAC) on 40-meters, all the way to the current Stereo-Cw / Stereo-Ssb tricks I play with receive audio.  I have written about the audio experimentation side of things in past Blog entries on experimentation:

• [X] - WQ6X-Sound Processing: Maximizing the Art of Experimentation.
• [X] - External Audio Filtering: Maximizing the Art of Experimentation - Part 2.
• [X] - The DR. Validates Cascading Audio Filters
• [X] - More Lessons Learned from Listening to the DR.
• [X] - When in Doubt: CHEAT (but within the rules)

On the antenna end of things, 8JK phasing Cobra dipoles and raising a full-sized wire-based
Log Periodic array for 80- and 40-meters during Field Day atop Mt. Abel in Southern California
(8250' ASL) represent how far out experimentation can get.

One of my operating axioms is to take something (be it vintage technology or contemporary)
and leverage the benefits of that technology towards the goal of maximizing operating efficiency.  Toward that end, to open 2022, a Yaesu FT-2000 (dual-RX) transceiver has been moved into the
Main operating position of my WQ6X portable (it's on wheels) operation from Concord (in the East Bay - EB - section).

Utilizing analog IC-chip technology (the Autek QF-1A from the 70's and the MFJ-752 filters from the 80's and 90's) to the digital (DSP-chip) technology of the 90's (MFJ-784 and JPS NIR-10 & NIR-12 external DSP filters) to the DSP facilities built-in to the FT-1000mp (audio-based) and the FT-2000
(IF-based).

Originally, these individual technologies were not really intended to be run cascade, the way I do
with the Stereo Cw/Ssb techniques.  Of course, there is always a risk that one filter in a cascaded audio-chain can inadvertently generate ringing (negative-feedback) or create unintended ground loops (A.C. hum).  Then again, a 15-band (per channel) audio-equalizer can specifically filter out
an offending hiss or hum; again, maximizing the Art of Experimentation.  

As each iteration is made, I turn to a weekend radiosport event to test the configuration under live operating conditions.  I guess it could be said that this is yet another example of my operating
axiom: "When in Doubt: CHEAT (but w/in the Rules)".

Cascading audio also feeds my need to twiddle knobs; more units bring a near-infinite arrays of
knobs to twiddle.  Knob contributes to the psychological feeling of being more in control of how a given operation is run.  When audio is "properly" balanced between Left and Right, a more pleasing audio aesthetic effect is created.  

Bottom-line: if a given setup is more enjoyable to operate, I will spend more time in the operating chair looking for weak/obscured signals that I might have given up on w/o the signal enhancements.  A properly run Stereo-Cw operation creates an ARC of calling stations, from the Left, mid-center and, to the Right.  This creates a pleasingly special effect add an increasing-level of comprehension,
which is part-aural and part-psychological.

In between operating shifts during the CQ-160 Cw contest, time was spent working on the issue
of properly splitting and processing Left and Right channel audio snaking its way thru a myriad of analog-IC and DSP-chip-based filters, before the Rockville mixer and generic switch box which sends the processed split audio to 1-of-3 speaker arrangements or a 1/8th" patch panel feeding whatever headphone arrangement is 1/8" compatible.

Overall, I prefer using Own-Zone wireless headphones allowing listening to the final-processed audio anywhere in the vicinity of the little wireless (hockey puck-like) transmitter.  Then again, it's frustrating to be doing my bizniss in another room and hear "QRL?" followed by a "CQ Test".  Because I have no way to send "QRL QSY" from the other room II [temporarily] lose the frequency; altho all too often after 5 minutes of no callers they move on, and I have the Run Frequency back.

A downside to the Own-Zone wireless approach is its propensity for being BOMBARDED by stray-RF from the ladder-line feedline to the 8JK Cobra array, primarily used for the 160 to 15 meter HF bands.  For 10-meters a 3-element Long John yagi gives rotatable directionability.  It has also been noted that rotating the yagi (even if it's not being used) can sometimes change the RFI overload in the wireless headphones.

With such a high-concentration of radio waves in such a small space, even tho the power levels never exceed 100 watts, signal collisions are inevitable.  Frustrated by a lack of signal output levels, a 20-watt mini amplifier was returned to the operating position with reasonable success.  That it "just fit" into the cubby-hole just above the 4-channel Rockville sound mixer adds to overall flexibility.

 

 

As I've mentioned in previous blogs on stereo audio processing, with 7+ devices variously interconnected "ground loops" are also inevitable.  

 

 

 

Then again, back to my "When in Doubt CHEAT (but w/in the rules)" edict, sending the audio thru a 15-band/channel audio equalizer can eliminate any after-the-fact artifact, with little-to-no degradation of signal intelligibility.  

 

Part 4 of this Blog series will focus specifically on the world of audio equalization.

Stay TUNED!