DW,
When adjusting the carrier balance, you are adjusting for minimum
transmitted carrier - you want that to be at the lowest level possible.
Yes, if you have something sensitive enough to measure a low RF output
level - then run the K2 into a dummy load and connect the sensitive RF
meter across the dummy load - I use an oscilloscope set to the highest
input sensitivity, the RF voltage level at the correct adjustment point
may be somewhere between 50 and 100 millivolts so your 'meter' must be
able to respond to a signal that low (an RF Probe is not likely to be
sensitive enough on the low end of the scale). An external receiver
(set for SSB or CW) can be used to detect the residual carrier signal -
you ae using it as a 'meter' to tell when the K2 output level is at its
lowest.
You want to transmit only the SSB carrier and not any sidebands. Yes,
you can do as the manual indicates and simply push the PTT button, but
do not speak into the mic (yes, try to keep it from picking up noise
too) - any audio into the mic will be converted to RF too and confuse
your measurement. You can do it even easier if you remember that the CW
DOT paddle line and the K2 PTT are one and the same signal - just plug
your paddles into the K2 and close the DOT paddle (you do not have to
connect a microphone).
You may have to compromise a small amount between USB and LSB - adjust
for the smallest residual carrier first in LSB, then switch to USB and
see if you can make a small adjustment to improve it - re-check LSB and
bounce back and forth between LSB and USB several times (press the REV
button to switch sidebands, it is easier than using the MODE button)
I would try it with the stock adjustment trimmer - I do not have any
trouble adjusting with it and I think a multiturn pot would be overkill
in this application.
73,
Don W3FPR
DW Holtman wrote:
Hello,
I'm trying to align the SSB board on a K2. The manual on page 19 says to do the fine carrier balance adjustment using an external receiver.
It says "If you're tuned to a setting that allows you to hear the voice signal,
you'll be at the zero-beat frequency of the carrier and will not be able to her a
tone."
What exactly does this mean? Is the receiver tuned to the opposite sideband?
Does it matter what sideband the external receiver is on? What is being
adjusted? The level of rejection for the opposite sideband? It wants a balance
between USB and LSB with as low a signal as possible. Will ambient noise in the
room (window air conditioner) be picked up by the mic and affect the readings?
Should this be done with the mic disconnected and a jumper to short the PTT pin
to ground?
I ordered a trimmer from Digi Key that will fit in the space of R1, it will
have 5 turns to increase the resolution.
Is there somewhere I can put a high impedance RF Voltmeter and adjust R1
without having to use an external receiver? How would this be done?
Thanks in advance for any help. I'm a little confused. I know this is a lot of
questions, hopefully someone will have some of the answers. The reason I
started the alignment is with the 100 watt RF Module installed, when I transmit
in LSB, there is power out without talking into the mic?
Thank you,
DW Holtman
WB7SSN
_______________________________________________
Elecraft mailing list
Post to: [email protected]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
No virus found in this incoming message.
Checked by AVG - http://www.avg.com
Version: 8.0.138 / Virus Database: 270.6.5/1620 - Release Date: 8/19/2008 6:04 AM
_______________________________________________
Elecraft mailing list
Post to: [email protected]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
