RigBlaster/K2 & PSK31/PropNet^31

[Mark J. Schreiner]

I just sent out a note to the list and commented that I planned to use RigBlaster with the K2.  I have Heil microphones so have already changed R14 to increase the gain and that seems to work well.

Two issues.  First, I noticed RF on 160m to 40m when using the microphones into the Rigblaster.  I performed the ground modification of the 8 pin microphone connector and that solved the problem on all bands when the microphones are plugged directly into the K2 front panel, however if I have them plugged into the RigBlaster and then use the 8 pin modular connector (RJ-45?) cable to the 8 pin mic connector on the K2 I still have RF issues on 160 & 80m (at least one try on 40m it was okay).  I did a similar mod to the 8 pin mic connector on the front panel of the RigBlaster but it didn't help at all.  I'm thinking that the cable from the RigBlaster to K2 may not be well shielded, or at least not well grounded at the back panel of the RigBlaster.  Anyone else have this experience as well?  I was thinking of using a braided shield removed carefully from some RG-8 to slide over the top of that cable and connect to the metal microphone outer shell and if necessary to a ground lug on the back of the RigBlaster.

Second issue.  With the mod on the SSB board of R14 from 1k to 10k for increased gain for my Heil microphones I'm concerned about overdriving the input from the soundboard output.  Maybe I should put in a voltage divider dedicated in the cable assembly from the audio out of the sound board to the RigBlaster.  Any thoughts or experience out there with that?

I was thining of setting up PropNET^31 to use the K2 for a "smart beacon" during potential E-skip openings on 10m.  Since I'm away from home more than I can be home to operate, it would put the K2 to work for some benefit to all even while I'm at work.  I know that PropNet is fairly new, but anyone else out there doing this with their K2 yet?

Thanks!

Mark, NK8Q
K2 #4786
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[Jim Brown-10]

On Wed, 27 Apr 2005 10:50:58 -0500 (CDT), [hidden email]
wrote:

>Two issues.  First, I noticed RF on 160m to 40m when using the
>microphones into the Rigblaster.

Most ham gear, including the K2, has what is known in the pro
audio world as a pin 1 problem at its mic and control inputs. I
don't know about the Rigblaster, but I would be surprised if it
doesn't also have the problem.

The RIGHT place to connect the shield of any cable is the chassis,
not the circuit board (often called "mic ground" or "control
ground"). See my website for applications notes about this.

http://audiosystemsgroup.com/publish.htm

Also see AES48, an international standard that addresses this
issue, and includes a tutorial annex (that I helped write).

http://www.aes.org/publications/standards/courtesy.cfm?ID=44

I have fixed the pin 1 problems by doing three things. First, I
have added a short jumper between the mic jack and the chassis,
and extended it to the shell of the headphone jack. Second, I make
all of my shield connections to the shell of the mic connector.

Third, I've replaced the "stock" RS232 cable with shielded CAT5.
That shield, AND the returns of all the control lines, go to the
shell of the DB9 connectors at both ends (the computer end and the
K2 end), and NOT to pin 5. Before I made this change, my computer
would lock up at 10 watts. Now I can use the K2 drive my Titan at
1 kW with no problem.


Jim Brown  K9YC


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[Pete, AG7C]

I have used the Rigblaster Plus with several other rigs for some time. I
found I needed to use ferrite cores
on several of the cables to quiet down rf  problems.  Since those were
already in place, I did not have any problems when I connected the K2.

For PSK, I use Digipan and for ssb, the mic is an ICOM SM-8.  All very
good clean reports so far  on PSK31, MFSK16 and ssb.

Pete    AG7C
K2  s/n 4847
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