XG1 Results with K1 s/n 1018

[Clark Macaulay KE4RQ]

Hello everyone!  My first post to this august group.
   
  I've always suspected my K1 receiver to be a little weak because of very weak audio fro the speaker although headphone volume is fine.  Not knowing whether it was an audio or RF problem, an XG1 was ordered and here are the results @ 7040Khz using the 1 microV setting and measuring the AC voltage at the speaker terminals per XG1 instructions:
   
  --XG1 ON: 104 mV
  --XG1 OFF: 12 mV
   
  Using the formula in the XG1 instructions:
  --R(atio) = 8.2
  --  Log R = .9
  -- 20 x Log R = 18 db
  -- MDS approximates -107- 18 = -125 dbm
   
  which is a little off the -130 dbm identified in the XG1 instructions.
   
  My questions are:
   
  1) Are my results within range of what should be expected? When an antenna is attached, the noise rises significantly indicating to me that the receiver is working, but that is hardly an objective measurement.
   
  2) Should I stop trying to figure out why the speaker volume is so and low and just use headphones?  When I touch pin 1 of mixer U2, I get a loud blast from the speaker, so I'm convinced the audio chain is fine.  I'm just not sure if the RF level into it is high enough.  I have the K1-4 filter board and am sure I've peaked it for best results.
   
  BTW:  I do have the internal battery option, so when I say speaker volume is very low, I'm referring to the speaker and top cover being in place.
   
  73,
   
  Clark Macaulay
  KE4RQ
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[Ron D'Eau Claire-2]

Hi, Clark:

It sounds like you are dealing with two different issues: Minimum
Discernable Signal (MDS) measurement and raw audio power.

The MDS that you are measuring with the XG1 should not be associated with
how much racket you get in the speaker or phones. A very poor receiver can
make a lot of noise! It all depends upon the amount of amplification the
receiver has, which is quite different from the sensitivity.

First, are you using a bandwidth of 500 Hz for the MDS measurement using the
XG1? The MDS you get will depend a lot upon that bandwidth. Since you are
measuring the receiver's response to an unmodulated signal and comparing it
to the noise with no signal, the narrower the bandwidth, the less noise
energy you will detect with the XG1 turned off, so the better the calculated
MDS. CW receiver MDS is commonly calculated using a receiver bandwidth of
500 Hz so we're comparing apples and apples when comparing two rigs.

All that aside, the audio level is a wholly different problem. I do not own
a K1 so I'll leave it to K1 owners to suggest remedies for that.

Ron AC7AC

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[Peter Zenker]

>   2) Should I stop trying to figure out why the speaker
> volume is so and low and just use headphones?  When I touch
> pin 1 of mixer U2, I get a loud blast from the speaker, so
> I'm convinced the audio chain is fine.  I'm just not sure if
> the RF level into it is high enough.  I have the K1-4 filter
> board and am sure I've peaked it for best results.
>    

Mark,

Did you ever try another headphone? It must have the correct impedance and
there are diffences of > 40 dB between different headphones.

72/3 de Peter, DL2FI
www.qrpproject.de


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