[Elecraft] SSB Microphone Question

[Ron D'Eau Claire]

Jeff, VA3JFF wrote:

I hope I can solicit some advice on SSB and microphone selection.  I have
the SSB board already installed and working.  I have had QSOs with the K2 on
SSB both domestically and DX, but something always seemed a bit amiss.  When
I recently repaired the finals on my FT817, I was able to do side by side
tests.  On CW I choose the K2 everytime for receive and transmit.  On SSB
while I would take the K2 for receive, I work stations giving me solid
reports with the FT817 that can not hear me at all, or can only barely pull
out one letter of my callsign with the K2.  Seems to me that I don't have
something optimized properly yet.  I have all of the most recent SSB
upgrades installed.

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Here's a few things you can check Jeff:

1 - Mic bias. If you're using an electret mic that requires an external d-c
voltage supply, make sure it's getting the proper bias voltage from the rig.


2- Audio Level. It's easy to check to see if you're getting full output on
SSB. First switch the bargraph from RF output indication to ALC by
pressing/holding the DISPLAY - RF/ALC button. The LCD will say ALC briefly
to indicate you're now in ALC monitor mode. Key the mic and speak. You'll
see bars light up on the display. It reads backwards (right to left) to
remind you you're in ALC and not RF output mode now. Set your POWER output
to maximum and speak into the mic. At least one bar on the right end should
flash. IF it does, that means you have all the audio the K2 can use. That
flashing bar means that the ALC is now turning down the gain because you are
making full RF output. If you aren't getting at least one bar, the first
thing to check is to see if you have the audio attenuator switched in at the
K2 mic input. You do that by checking the SSBA menu setting. It should be 2
or 3. Those produce full audio. SSBA 1 inserts 10 dB of attenuation for use
with amplified mics to help keep them from over-driving the K2. If you have
your mic input set for SSBA 2 or 3 and aren't getting enough audio, check
the ALC action and BFO as described below before adding a preamp. A problem
in the ALC or a bad BFO adjustment can also cause problems. 

3 - Check to be sure the ALC is working properly by switching the display
back to RF (press/hold DISPLAY - RF/ALC and note that RF appears in the LCD
momentarily), keying the mic and speaking again. With the POWER set to 10
watts (K2) or 100 watts (K2/100) you should see the right hand bar flash
momentarily on voice peaks. If so, your K2 is making full output. The power
monitor is a peak-reading device. If it isn't showing full power output,
there's  something amiss in your ALC circuit that's causing it to act too
soon. Keep in mind that your voice peaks are very brief. You'll see only
flashes of full power. Be sure to set your compression (SSBC 1-1, 1-2, 1-3
or 1-4) to the level you want (1-1 no compression, 1-4 max compression)
before you check. The K2 needs more audio input for higher compression
levels. 

On various bands and power settings, more or less ALC bars will flash,
depending upon how much the ALC must turn down the gain to hold the power to
the requested level. Typically the K2 has the last RF gain at 10 meters, so
there you may only see one bar flash on voice peaks at 10 watts output. On
40 meters, it's common for several bars to flash at 10 watts output. And, if
your reduce your RF POWER setting, more bars will flash as needed to hold
down the RF level to what you've requested with the POWER control.  

4 - BFO setting for FL1. FL1 is used for transmit regardless of what filter
you are using for receive. So the BFO setting for FL1 is critical for
transmit audio quality. Using Spectrogram is often not close enough for
optimum audio on transmit. A lot depends upon your voice and our mic. I
recommend listening to yourself 'on the air'. Since you have two rigs, that
shouldn't be too difficult. Just load up the K2 at very low power in to a
dummy load and listen to yourself on  the  FT. One thing I've learned is
that it often doesn't work to simply talk into the mic while listening to
your voice in the headphones. Audio transmitted from your mouth to your ears
via bone conduction will fill in a lot of spectrum that may not be being
transmitted, so what you hear may be a lot better than what you are
transmitting. 

I recommend using the "listen while you speak" system to be sure the second
rig is tuned it exactly right, then recording your voice from the second
rig. If you don't have a recorder, you can usually use the sound card in
your computer and the recorder built into Windows. Then play it back and see
how clear and clean your voice sounds.

If all of the above looks fine, and you still don't get at least one ALC bar
flashing when transmitting, then an external mic preamp might be called for.


Ron AC7AC