[Elecraft] K2 Volume

[Tom Hammond]

Hi John:

>I have been reading this thread and other similar ones in the past. I have 
>a problem with volume,  on 20M and possibly 17M. 17M is dead right now, so 
>I can't double check. Volume has to be almost all the way CW to be of use. 
>Since I built K2 #3596 I have not heard any reasonable signals on 15M, 12M 
>or 10M. The volume knob sits in the 9-10 o'clock region with plenty of 
>volume on 80M, 40M and 30M.

The fact that you DO have reasonable volume on SOME bands and not on 
others, tends to exonerate the AF section itself. It's not gonna be good on 
some bands and not on others.

This having been said, what you report DOES tend to implicate a problem on 
the higher bands... but not necessarily anything the fault of the K2 itself...

1) Propagation on 10/12/15 meters has not been all that great... in many 
instances (e.g. for the larger part of each day) it's been NONEXISTENT... 
period. I don't know what you are using for an antenna, but if it's the 
least bit 'questionable' then that, too, adds to a possible problem of not 
being able to hear much on the higher bands.

2) 20M and 17M might be problematic with regard to propagation as well, 
depending upon the time of day you're listening to signals. Elecraft 
recommends the use of the built-in PREAMP for the bands 20M and above (thru 
10M). You might consider using the preamp on 30M as well, but I've 
generally found it not necessary. Again, antenna considerations will help 
receive on these bands as well.

3) There's always a possibility that you DO have a problem with your K2 on 
10/12/15 meters... check your bandpass filter first! Since everything along 
the signal path, and the left (IF side) of the BPF is COMMON to all bands, 
this pretty much eliminates that part of the circuitry. So any 
problem-child is probably gonna be between the ANT INPUT and the output of 
the BPF.

>I have R1 set at 3.80v. I read 8.06v at 8v regulator.
>
>AGC on or off may change volume slightly, but don't fix it.
>I have set and reset 20M filters on transmit and the numbers look good 
>(yes I did cal pll and fil correctly after). C21 and C23 do not seem to be 
>at their max when power out peaks. I think that means increasing the value 
>of either of them would probably not improve volume??

The paragraph above tends to imply that your 20M BPF is probably NOT the 
culprit either. Again, this leads toward listening to 20M at the wrong 
times of the day, or possibly with a less than adequate antenna... or both.

Try to obtain access to a signal generator (or even a broadband noise 
generator such as that shown on the Elecraft web site). Anything that'll 
give you the ability to inject a signal (single frequency or broadband will 
both work equally well) into the ANY INP of the K2 and then check out the 
upper bands. If you can copy the signal (approximately) equally well on all 
bands, then either propagation or the antenna are you limiting factor(s).

If you find a band where the signal/noise drops off SIGNIFICANTLY, then 
it's probably either tuning in the BPF or possibly a poorly soldered 
connection in the BPF.

>I don't think what I am getting out of my radio is right. I don't want to 
>side track the main flow of the thread, but I would like some more ideas 
>of ways to get 20M behaving like the other bands. It is my favorite band.

With sunspots on the wane, 20M isn't NEARLY as productive as it was even 
6-8 months ago. There are many periods of time where few signals are heard, 
even with really good antennas and a known-working K2 (other rigs as well). 
But even 20M has some fits of brilliance now and then. Listen on 
weekends... there's generally at least one or more contests on. Regardless 
of whether you like contests or not, they ARE still a good producer of 
signals on many bands... even bands considered to be 'dead' by many. This 
isn't to say that signals received will be strong... they may not be. But 
you SHOULD be able to hear them... if you hear signals weakly, call your 
buddy across town and ask him what he's hearing on that frequency. If he 
hears them loudly, while you're barely hearing them, AND if you both have 
similar antennas, then there may be a problem with the K2. But, if he's 
hearing about the same thing you're hearing, then chances are your K2 is 
A-OK on THAT band...! Pick another band to check out the same way.

Good luck,

Tom Hammond    N0SS