K2 receive volume

[Ron ZL1TW]

Hi
     I have read the thread about the lack of volume in the K2 that some
chaps have reported, and personally I find it hard to imagine any problem
in that area.
During our last Field Day, we had a Tropical Cyclone running down us on the
East, and a deep depression to the West, and the wind and rain was of
Tropical proportions. To make matters worse our FD "shack" for 80m was a
metal sided horse float, and the din from the rain was extreme. I used my
K2 in that mix without headphones and had no problems at all.
Incidently.....I also notice reports on headphones to use with the K2 and
the associated answers on what to use.
While I have no argument with the headphones suggested, I used a bit of
"bush engineering" to make a set of headphones that work exceedingly well
with my K2 ( when required)
I bought a set of nice headphones from a local junk sale for a few cents,
and found one side was open cct. ( not surprising)  I then cleared both
inserts out and put in two 8ohm speakers out of old computers,and wired
them in parallel. I certainly have no volume problems with those clamped on
my lugs...... The niceties of frequency response and whatever makes for
good listening went out the window the day I signed up to work in Telephone
exchanges in the 50's !!
Cheers......Ron ZL1TW

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[Bill W4ZV]

ZL1TW wrote:
 >I have read the thread about the lack of volume in the K2 that some chaps
have reported, and personally I find it hard to imagine any problem in that
area.

         I agree Ron.  On my #4119, normal AF Gain into both
a Heil Pro-set and Radio Shack PRO-50MX is at 9 o'clock and
normal for the internal speaker is at 10 o'clock.  12 o'clock on
both is quite uncomfortable to my ears with either headphones
or the internal speaker.  Max at 5 o'clock is actually near the
threshold of pain using headphone and sounds like it may be
near the distortion point for the internal speaker.

         Perhaps there are some differences in how our AGC
Threshold is set.  Mine is set to 3.70 volts versus the 3.80
default suggested in Elecraft's alignment procedure.  I set
mine using #1 in the following application note:

http://www.elecraft.com/Apps/RX_Gain_application_note.htm


1. If the AGC circuit is limiting the receiver's output even on very
low-level signals, you can change the resting AGC threshold. First, switch
to a band that has VERY low atmospheric noise (and no indication on the
S-meter). Then turn the AGC OFF (by holding the PRE/ATT and AGC buttons
together). If the noise is significantly louder when AGC is OFF, the K2 may
be turning on the AGC too quickly. The threshold can be changed by making
R1 on the control board smaller. Try putting in a pot at R1 and see where
you need to set it to get the AGC threshold you prefer. The value should
not be reduced by more than about 30%. If you choose a new resistor, you'll
have to reset CAL S HI and CAL S LO to recalibrate the S-meter, and the
numbers for S HI and S LO will be very different from the defaults. Values
of R1 that are too small may result in an inability to set up the S-meter
correctly.

                                 73,  Bill  W4ZV

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[N2EY]

One point:

We need to distinguish between "volume" and "gain".

I've never noticed any K2 being short of "volume" - meaning the ability to
deliver room-filling audio without unacceptable distortion, *given a big enough
signal*.

But some K2s have more gain than others, meaning total overall amplification
from the antenna terminal to the speaker or headphones.

73 de Jim, N2EY
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[Don Wilhelm-2]

Jim and all,

I have worked on about 5 K2s since I acquired my XG1, and I can state that
the gain of a properly aligned K2 from the antenna through the IF amplifier
is very close from one K2 to another.  Filter alignment will account for
huge variations.

Also, since I have been experimenting with my fixed audio output board for
the K2, I have found that the audio level at the volume control (VOL1 and
VOL2) is also close across the board - but some do sound louder than others
to my ears (given a similar AF gain setting).

I have long wondered what the difference may be and am at the point of
concluding that it is due to differences in the LM380-N audio amplifier gain
(but the parts should sufficiently consistent from batch to batch than the
differences I hear - and my own SN 00020 is one of the 'weak' ones.  I am
not inclined to blame it on speaker differences because I have tried several
speakers in my K2 and all produce about the same level.  One of these days,
I might investigate further, but it is not really important enough to persue
at the moment - more a curiosity than anything else.

73,
Don W3FPR

Life is what happens when you are making other plans

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

> One point:
>
> We need to distinguish between "volume" and "gain".
>
> I've never noticed any K2 being short of "volume" - meaning the ability to
> deliver room-filling audio without unacceptable distortion, *given a big
enough
> signal*.
>
> But some K2s have more gain than others, meaning total overall
amplification
> from the antenna terminal to the speaker or headphones.
>


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