[Elecraft] Testing how loud it is!

[Tom Hammond NØSS]

Good morning folks:

Sorry for the delay in replying, but I was out of town this weekend and 
just returned home Sunday evening.

>You are correct about the variations in side-tone level for the same
>setting, I figured the last measurement would filter that out.  I guess we
>could find the right test point and have Ron and Tom give us a measurement
>at a setting of 128 or maybe even 200 and then we could all try to match it.
>A more complete test would be to measure things at high, low, and medium
>level inputs but I wanted to keep the test simple.  I guess we need to
>decide if the problem is not enough overall gain or maybe non-linear gain
>such that only the loud or weak signals are not amplified enough.

Here's what I'm planning on trying... today, if time permits... and I think 
this may fly... at least for the AF section.

I think that merely setting ST L to an arbitrary NUMERICAL setting may 
still not allow us to have confidence in our measurements. BUT, for those 
of us who have o'scopes which we believe to be relatively accurately 
calibrated, we should be able to set the output of the Quad, 8-Bit DAC 
(U8), to a certain measurable peak-to-peak level and THEN proceed with 
performing our output level tests for the rest of the AF chain.

I think it would probably be appropriate the begin by setting the P-P 
output of the DAC by measuring the sidetone level at the drain of Q5 
(2N7000). I've not done this yet, but I'll try to provide a usable level a 
bit later today. I DO think we should attempt to first use a P-P voltage 
somewhere in the lower to mid range of the volume level control. Probably 
somewhere below a DAC count of 100, and probably closer to 50.

I recently bought a new (for me) o'scope, so now I'll finally actually have 
a REASON to put it to some good use. I will be using the X10 probe, just to 
help to ensure that I'm not 'loading' any possibly high-impedance part of 
the AF circuit during my testing.

>The question I am looking to answer is what percentage of us have an Rx
>problem and how many have a simpler audio problem?  This would be a starting
>point so that those with an audio problem do not waste time looking in the
>wrong place.  I figured that finding a way for us all to inject a matching
>signal into the antenna to trace down an Rx problem will take a while.  This
>seems like a place to focus efforts while the experts work out an approach
>for the more complex possibility.

Once we can/cannot vindicate the AF chain itself, THEN we can focus on the 
RF chain.

Results later today.

73,

Tom  N0SS

PS

Just as Fran has 'fessed' up, I shall as well (as I've done before). I have 
NO formal electronics training. Whatever small amount of 'knowledge' I have 
has come from several (44) years of hands-on experience, and having done it 
WRONG enough times to at least have a feeling for possibly doing it 
right(er) the next time... so I may still be going off on the wrong 
tangent, but at least it'll be MY tangent...<G>