[Elecraft] K2 ALC Problem?

[Gary D Krause]

I've had this problem for a while and forgot about it since I work mostly CW. 
 Thanks to everyone that answered my KPA100 message.  The ALC works fine on 
the bands above 40 meters but, on 40 it isn't very aggressive.  I will get 
four or five bars on voice peaks and then the audio will cut out a little at 
10 watts as the bars go back down.  If I increase power to 15.2 watts, the ALC 
becomes more aggressive and only shows a max of two bars.  It's a little 
better on 80 meters.  What bothers me is the audio cutting out while there is 
a delay as the bars dissappear.  Is this normal?

Thanks,
Gary, N7HTS



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[Elecraft] K2 ALC problem

[Gary D Krause]

Hi,

I've noticed that my power output on 40 meters LSB is a lot higher than 
expected.  I get four to five bars or more on the peaks in the ALC mode.  I 
even got a high current reading last night and I then turned the power back 
from 12 watts to 10.  I get 4 to five bars even at five watts.  It didn't make 
much difference and I've found that I need to hold the mic further away. I 
switched to USB on 40 meters and it looks fine.  It looks good on the higher 
USB frequencies also.  I've noticed that it is around 2 to three bars on 80 
meters LSB which is normal according to the manual.


I'm wondering if it could be a carrier balance adjustment?  Any ideas would be 
greatly appreciated.  Everything else appears normal.  I've checked all solder 
connections on the SSB board several times and re-flowed the connections I 
considered suspect.


Thanks,
Gary, N7HTS



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Re: [Elecraft] K2 ALC Problem?

[Don Wilhelm]

Gary,

The K2 is different than the K3 in this respect.  On the K2, if you have 
*any* ALC bars showing, that is enough - driving the ALC harder will not 
result in additional output, it will just cause RF compression, which 
may be undesirable - it is better to set the menu SSBC parmeter for a 
higher compression ratio.
Normally, the Transmit Gain of the K2 is higher on 40 and 30 meters, so 
I wonder about your K2 performance if you do not see more ALC bars on 40 
than on other bands.  You might want to check the alignment of the 
bandpass filter for 40 meters.

73,
Don W3FPR

Gary D Krause wrote:
> I've had this problem for a while and forgot about it since I work mostly CW. 
>  Thanks to everyone that answered my KPA100 message.  The ALC works fine on 
> the bands above 40 meters but, on 40 it isn't very aggressive.  I will get 
> four or five bars on voice peaks and then the audio will cut out a little at 
> 10 watts as the bars go back down.  If I increase power to 15.2 watts, the 
> ALC 
> becomes more aggressive and only shows a max of two bars.  It's a little 
> better on 80 meters.  What bothers me is the audio cutting out while there is 
> a delay as the bars dissappear.  Is this normal?
>
> Thanks,
> Gary, N7HTS
>
>
>
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Re: [Elecraft] K2 ALC problem

[David Woolley (E.L)]

Gary D Krause wrote:


I've noticed that my power output on 40 meters LSB is a lot higher than 
expected.  I get four to five bars or more on the peaks in the ALC 
mode.  I even got a high current reading last night and I then turned 


The number of bars in ALC display mode does not indicate the output 
power; it indicates the transmit chain gain (more accurately the excess 
gain over that needed to achieve the demanded power).


The K2 does have more or less maximum gain on 40m.  I suspect that the 
gain drops with increasing frequency because the transistors' gain 
reduces with frequency, and it drops with decreasing frequency because 
the coupling transformers are less effective.


The ALC is greatest on 40m to stop the output power being greater.

the power back from 12 watts to 10.  I get 4 to five bars even at five 
watts.  It didn't make much difference and I've found that I need to 
hold the mic further away. I switched to USB on 40 meters and it looks 
fine.  It looks good on the higher USB frequencies also.  I've noticed 


That's weird.  Any difference between USB and LSB should switch between 
USB and LSB on the higher frequency bands.


that it is around 2 to three bars on 80 meters LSB which is normal 
according to the manual.


I'm wondering if it could be a carrier balance adjustment?  Any ideas 


A severe carrier balance problem would result in their being ALC bars 
lit when there was no audio.  As the carrier is also suppressed by the 
filter, I'm not sure that you would get enough leakage to trigger this, 
though.


If the sideband switched at higher frequencies, I would suggest the 
problem was that your filter 1 wasn't correctly aligned for one of the 
sidebands, but if it is always the one sideband that needs more ALC, I 
have difficulty in imagining a mechanism that would cause that.


would be greatly appreciated.  Everything else appears normal.  I've 
checked all solder connections on the SSB board several times and 
re-flowed the connections I considered suspect.



--
David Woolley
"The Elecraft list is a forum for the discussion of topics related to 
Elecraft products and more general topics related ham radio"

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Re: [Elecraft] K2 ALC problem

[Don Wilhelm]

Gary,

I would expect two possible causes.
One is the carrier balance adjustment.  Use a band below 21 MHz when 
adjusting and adjust for LSB first.  If you have an oscilloscope, the 
procedure is easy - connect a dummy load to the K2 and connect a paddle 
or straight key to the key jack.  The oscilloscope is to measure the RF 
output voltage, so connect it across the dummy load with a 10x probe and 
set the vertical sensitivity to its greatest setting.  In LSB mode, 
close the key (which activates PTT) and adjust the carrier balance for 
minimum RF.  That setting should occur close to the center of the 
trimpot.  Then check USB  If the USB carrier is greater than that for 
LSB, adjust the pot a very small amount to see if you can reduce  the 
carrier.  You may have to make some compromise to get the amount of 
carrier the same between LSB and USB.  Note, if you use this method, do 
not connect a microphone to the K2 and you do not have to set the menu 
for "SSBA bal".  You can use a separate receiver to detect the minimum 
carrier in place of the oscilloscope as indicated in the KSB2 manual, 
but I suggest using the key to activate the PTT circuit rather than 
plugging in a microphone.  A mic with its PTT button pressed can pick up 
residual noise and cause a false indication.  This is easier done than 
to write about it.


The second possible problem is alignment of the SSB filter.  Use 
Spectrogram and set the BFO to position the OP1 filter passband between 
300 Hz and 2600 Hz markers (use 300 and 2300 if you have the 2.1kHz 
filter width or 300 and 2800 if you have the 2.6kHz filter width).  
Center the passband between the two markers.  Check both LSB and USB.


If you moved the SSB passband in the step above, re-visit the SSB 
carrier balance adjustment.


If those steps do not correct the imbalance between LSB and USB, you may 
have some fault on the KSB2 board.  A very small difference may exist, 
but not to the extent that you have indicated.


73,
Don W3FPR

Gary D Krause wrote:

Hi,

I've noticed that my power output on 40 meters LSB is a lot higher 
than expected.  I get four to five bars or more on the peaks in the 
ALC mode.  I even got a high current reading last night and I then 
turned the power back from 12 watts to 10.  I get 4 to five bars even 
at five watts.  It didn't make much difference and I've found that I 
need to hold the mic further away. I switched to USB on 40 meters and 
it looks fine.  It looks good on the higher USB frequencies also.  
I've noticed that it is around 2 to three bars on 80 meters LSB which 
is normal according to the manual.


I'm wondering if it could be a carrier balance adjustment?  Any ideas 
would be greatly appreciated.  Everything else appears normal.  I've 
checked all solder connections on the SSB board several times and 
re-flowed the connections I considered suspect.


Thanks,
Gary, N7HTS



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[Elecraft] K2 ALC problem on 40m

[[EMAIL PROTECTED]]

Hi all,

i would like to decribe a problem I am faced with my K2. Every evening I
reconized a AGC problem on 40m band. My signal meter shows S8 to S9 and
it sounds like RF-Gain is turned counter clockwise. If i use ATT to
reduce the signal level it does not help. The signals will drop down but
it still sounds like AGC is to high.

I assume it is related to the big signals from broadcast band here in
europe. 

However, further I am not sure if my ALC is working correct. I
recoginized following :

If I disconnect my antenna from K2 and turn AGC ON/OFF I hear a
recognizable difference. I tried to adjust R1 to get the same level. In
my case I got the same level if R1 is set to the minimum value. If I do
so it looks like the RF- Gain pot has no effect anymore. I assume this
is not the intention.

I turned it back to the recommended value to get 3.8 volts now.

Any comments where I can investigate are welcome.



73 de Joerg (DL3QQ)




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RE: [Elecraft] K2 ALC problem on 40m

[Don Wilhelm]

Jeorg,

Yes, I would first look carefully at the AGC section for unsoldered
components and incorrectly placed components.  Let the schematic be your
guide in identifying the components involved.

The BC signals can take over the receiver IF and cause strange results.  I
recommend that you check the AGC action on a band other than 40 meters - if
it is OK on other bands, then you should look at changing the 40 meter
bandpass filter to provide a more narrow response on 40 meters.  There is a
'European' mod to the 40 meter bandpass that may help you - it is an
application note at the Elecraft website, look for it at
http://www.elecraft.com/Apps/eu_40_meter_narrow_bandpass_filt.htm

73,
Don W3FPR


> -Original Message-
>
> i would like to decribe a problem I am faced with my K2. Every evening I
> reconized a AGC problem on 40m band. My signal meter shows S8 to S9 and
> it sounds like RF-Gain is turned counter clockwise. If i use ATT to
> reduce the signal level it does not help. The signals will drop down but
> it still sounds like AGC is to high.
>
> I assume it is related to the big signals from broadcast band here in
> europe.
>
> However, further I am not sure if my ALC is working correct. I
> recoginized following :
>
> If I disconnect my antenna from K2 and turn AGC ON/OFF I hear a
> recognizable difference. I tried to adjust R1 to get the same level. In
> my case I got the same level if R1 is set to the minimum value. If I do
> so it looks like the RF- Gain pot has no effect anymore. I assume this
> is not the intention.
>
> I turned it back to the recommended value to get 3.8 volts now.
>
> Any comments where I can investigate are welcome.
>
>
>
> 73 de Joerg (DL3QQ)
>
>

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