[Elecraft] Question about mike performance

Mon Jul 28 12:07:00 2003

Highly recommend the 2.5KHZ mod to the KSB2. It not only makes the audio
more pleasant to listen to, it makes copying easier. Sure is a lot easier to
install this mod while building the board.
N2TK, Tony
#3481

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Ron D'Eau Claire
Sent: Monday, July 28, 2003 11:08
To: 'John MacKenzie'; 'Elecraft Mail list'
Subject: RE: [Elecraft] Question about mike performance

The K2 was designed with "tight" audio bandwidth on purpose. It gives the
SSB a little more "punch" by keeping all the RF in a smaller bit of
spectrum. But that's always a bit of a trade-off that is affected by the ops
voice characteristics as well as subjective judgment by the listeners.

Typically, K2 SSB filters roll off just over 2 kHz. Your Kenwood probably
rolled off several hundred Hz higher.

It sounds like this is the source of your audio issue. Yes, the K2 uses OPT1
FL1 for transmit, no matter what you have set in receive.

You might try playing with the OPT1 FL1 BFO settings a bit as described in
the SSB option book. I hooked up a separate receiver to a recorder to hear
what I sounded like. You can bet a fair idea by putting on some phones and
then select SSBA, BAL, then exit menu. Do NOT touch the PTT switch. Speak
into the mic, an you'll hear your voice. That'll give you a rough indication
of what you sound like on the air for the purpose of making BFO adjustments.

IF your OPT1 filter  bandwidth sounds too tight after tweaking your BFO
settings, John Grebenkemper KI6WX, came up with mods to increase the
bandwidth of the OPT1 filter a bit to provide a little better audio
fidelity. See info at John's web page at
http://home.pacbell.net/johngreb/KI6WX.html or check out Sverre, LA3ZA's
fantastic page of Elecraft mods at http://www.qsl.net/la3za/K2/mod.html.

Finally, on your original experiments with gain level, one way to check to
see if you have adequate gain is to put the bar-graph display in ALC mode.
It reads "backwards" right to left. If ONE bar is flashing on voice peaks,
you have plenty of audio gain. That bar means that the ALC is "kicking in"
to turn down the gain, so once that first bar flashes the RF has hit "max".
After that, more audio won't increase the output and too much audio from the
mic can over-drive the audio system as you discovered.

The amount of audio you need depends upon the gain of the transmitter RF
stages n the K2. The lower the overall transmitter gain, the more audio
needed. On most K2's the point of lowest output and gain is on 10 meters. So
check to see if you get one bar of ALC flickering on 10 meter SSB with the
compression level you want. If so, you've got plenty of mic input for all
the bands.

Ron AC7AC
K2 # 1289

-----Original Message-----

I talked to a freind on 80M CW & SSB late night to mainly to see if my
transmit and recieve were in the same place. That was FB.

But audio quality was decribed as hairy. Maybe overdriven audio, so I turned
off mike amp switch at bottom of my Kenwood MC-60. That fixed that. My audio
was then said to be communication quality, futher describe as lacking high
end and low end.

I really don't know what I should expect out of the MC-60, but I have got
good audio reports using it with Omni-D. This brings me to my question, Is
this just a lackluster mike or might I be clipping my SSB signal with
transmit filter on the K2 end? I belive transmit uses FL1 OP1, what would be
the most practical way to determine which is the case? Is there a way to
look at mike AF range without running it thru the K2?

John n1sjz

PS this QSO with an in state friend was first CW I had done with good old
3596. I got very good reports on my signal,(tone and power.) The straight
key wasn't so bad after all.

_______________________________________________
Elecraft mailing list: [email protected]
You must be a list member to post to the list.
Postings must be plain text (no HTML or attachments).
See: http://mailman.qth.net/mailman/listinfo/elecraft
Elecraft Web Page: http://www.elecraft.com