[Elecraft] Thanks re 817 & K2 audio

[Tom Hammond NØSS]

>Thanks for feedback on the K2 and 817 audio question. Your comments
>clarify things for me, but give rise to another question. If I wanted to
>compare MY K2 audio to the the audio produced by a perfectly built K2
>(ie let's say Gary built it), what would be used as a baseline
>comparison? How do you compare audio output from one rig to another? How
>would a builder be able to confirm for himself that the audio output
>matched with the disigner's intended audio output? How can it be
>measured in our simple "home labs"?  Kind of an interesting question to
>me?

Assuming a modest number of 'test' devices at hand, e.g. no signal 
generator available, but at least (borrowed) access to an o'scope of modest 
means (say, 5-10MHz bandwidth), I'd consider using using a signal source of 
known (or at least FIXED LEVEL) output to provide a constant input level to 
the K2s and then begin to compare signal levels along the RX and AF curcuits.

You could use an external transmitter, into a dummyload, with a 30db-40dB 
pick-off (or a step attenuator) between it and the rig under test. Or, an 
xtal oscillator with direct RF output (again thru an attenuator) to the rig 
under test. Heck, even one of the noise sources many have used for aligning 
the K2s filters would suffice, though you might have to reduce the level of 
the noise being generated with a bit of fixed signal attenuation. Just 
about anything that generates a fixed-level signal that can be tuned in by 
the k2s.

Then, connect BOTH K2s to the signal at the same time, thru a "T" 
connector, so you ensure that each sees an identical input level, and go to it.

Turn the AGC of the radios OFF, so it doesn't want to reduce receiver gain. 
And ensure that each rig has the same parameters set (band, mode, filter 
bandwidth, preamp OFF, RF GAIN level fully CW, AF GAIN set at the same 
point, etc.).

Use the scope's probe in the X10 position so as to not severely load down 
the circuit under test. And start comparing reading between radios.

I think I'd expect to see +/- 25%-30% differences between the two rigs as 
more or less normal.

73,

Tom Hammond   N0SS