[Boatanchors] OT: A question about using an 'audio mixer' in a ham set-up

[Phil]

Hi All,
First, sorry about the OT post, but I really don't know where else to 
ask this question, and I suspect that 'some' of you may use audio mixers 
and other advanced techniques in your ham stations. Especially if you're 
into using BCB AM transmitters etc.

The first part of this message is general info, at the end are a couple 
questions.

My 'receiving post' has expanded greatly over what it once was, with the 
ability to simultaneously use multiple receivers, make overnight 
recordings of a wide spectrum (192kHz) of the LF band, etc.

The antenna routing is taken care of with the antenna/rig select witches 
and 4 port receive multicoupler, but the audio routing is quite 
primitive, a single 5 position switch to select which receiver feeds the 
audio filter/headset/speaker etc.

In addition, routing the computer audio (when listening to the 
recordings) complicated matters.  In addition, the computer sound card 
feeds my "Fender Passport 150 Pro" stereo PA system (75W/channel) and 
with it's decent sized speakers and 150W sub-woofer serves as my 
"stereo" system

Well, I just ordered a used Timewave DSP-599zx filter to augment the 
homebrewed audio CW filter (440Hz CF 8Hz Wide).  So that complicates 
things further.
************************************

Then while I was working on the churche's mixing board (Behringer 24 
channel) it hit me.  What I needed was a smaller version of the board 
for my receiver interfacing and general audio routing!

An Amazon search for mixers turned up this unit which seems to be ideal 
for my application.  Yes, it has special effects which aren't useful for 
ham radio, but I'm also a (church) musician who plays guitar and 
piano/synth.  SO it just might get some music use in addition to the 
ham-shack.

http://www.amazon.com/Behringer-Xenyx-1202fx-Mixing-Console/dp/B000J5Y214?ie=UTF8&psc=1&redirect=true&ref_=od_aui_detailpages00 


I figure that I'll use channels 1-4 for receiver inputs (using the 'Hi-Z 
line' input of each channel for the receivers).  That will let me "eq" 
the receivers, limiting the audio response to reduce any hum or hiss etc.

The computer sound card will feed one of the stereo inputs.  There 
aren't any "eq" functions on those inputs, but it's not needed, the 
computer media player has eq built in, though I normally leave it pretty 
much 'flat'.

The Effects "send" control on each of the channels will let me route the 
receive audio to the effects output where the two audio filters 
(cascaded) will be connected, then routed back into the board.

When I want to use headphones the "Control Room" feed will feed the 
headphone output of the board.  When I want speaker audio the "Main" 
output will feed the Fender System.

I'm sure it'll take a bit of playing around to get everything routed and 
set up just the way I want it, but it'll be a HUGE improvement over what 
I've been doing. . .
***************************************
I didn't even think to check eHam reviews until after I'd already 
ordered the board, and I was a bit surprised to see that some people ARE 
using this exact board in their Ham station, with generally favorable 
reviews.
***************************************

QUESTIONS:
While this unit will be used for RECEIVE ONLY, not in the transmitting 
chain, the receive audio from my Transceivers (IC-7200 & IC-735) WILL be 
routed through it and in use on the occasional QSO's I have (I listen 
far more than I transmit).

1.  How susceptible is something like this to transmitted audio getting 
into the system (I only run 100W, no real power)?

2.  I have a large number of QUALITY 1/4" TRS plugs (shielded) on order 
to make up patch cables between receivers and board, audio filters and 
board, and the Fender Amplifier and board.  I wonder if it'd be 
worthwhile to put an "RF filter" comprised of a small series resistor 
(maybe 1/4W) and capacitor to ground on the board end of EACH patch 
cable as well as the input end of the cables going to the Fender. If so 
what would be suitable values for resistor and capacitor?  I think that 
with small enough parts they'll fit right in the plug,   Something like 
this.  Please excuse the crude ASCII graphics, it's not something I do 
often. . .

Input >----^v^v^v---v-------> To board input
              Res    l
                   ------
               Cap ------
                     l Ground
                     V
                     v

Several things I REALLY like about this board (or think I will ;-)

1.  It's fairly compact, NOT like the 24 Channel one we have at church 
that's nearly 4 feet wide, and which barely fit on my workbench when I 
worked on it (XLR mic connectors had broken solder joints to the PCB as 
well as scratchy controls).

2.  The Cost, it's REALLY quite economical (though Behringer doesn't 
have the greatest rep for reliability in rough use).


-- 
73 From "The Beaconeer's Lair"
Phil, KO6BB
http://www.qsl.net/ko6bb/  (Web Page)

PRESENT HF/LF RADIOS:
Grundigs: S-350 (~2006), G6 (2011) & S450DLX (2014).
HOMEBREW: 7 Tube+Rect 1v3 Regenerative RX for LF (built 2015)
Icom:    IC-735 Transceiver (~1990).
Icom:    R-75, Cascaded 250/125Hz CW-Filt, Panadapter. (~2009)
Icom:    IC-7200 Transceiver (~2015).
R-Shack: DX-380 digital portable (~1990).
SDR:     Softrock Ensemble II LF (built from a kit 2015).
Zenith:  Royal-7000 Transoceanic Portable (~1968).

ACCESSORIES: HOMEBREW LF-MF Pre-Amp, MFJ-993B HF Auto-Tuner.
              HOMEBREW 8 Hz Audio Filter.

ANTENNAS:  88 foot Long Ladder-line fed dipole, 35 feet AGL for MW/SW.
            Active Mini-Whip, 36 Feet AGL for LF/MW/SW.
            37 foot "Low Noise Vertical", 11 feet AGL for LF/MW/SW.

Merced, Central California, 37, 18, 37N   120, 30, 6W CM97rh