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On Sat, 11 Jan 2025 13:29:54 +0000 (UTC)
"Joseph K7CBR via groups.io" <k7cbr@...> wrote:

>? No, that demo you linked would NOT account for observations on my own hardware at a 250hz, 500hz, or even 2.8khz bandwidth as far as "internally generated noise". That has to do with showing the mess in crowded band conditions. I do know that radio hardware have internal distortion, this is not a secret.
> The demo you linked to, shows a span of 10MHz, 1MHz/div. Your link does not account for internal IMD in the passband of my receiver at the settings I asked about. He demonstrated IMD of his transmitter. The receiver mixing scheme and inter-stage bias class (through to AF) does factor into this, yet I wanted you to explain clearly and coherently what you mean, and how this is significant enough to be a consideration to our audible perception? In the link video, if I park my R4C (it wont park at 1GHz), and have my 600Hz roofing filter in line, cascading through my 250Hz filter, listening to CW, I wont hear those other signals.
> So please explain so we can all get onto the same page. Explain and show how you are measuring this so I can do the same. Thanks
>
> Joseph
>
>? ? On Friday, January 10, 2025 at 08:19:05 PM EST, Jim Shorney via groups.io <jimnu0c@...> wrote:?
>?
>?
> There is a demonstration given by a fellow in the link I posted in message /g/DRAKE-RADIO/message/81833 .
>
> However it is common knowledge that IMD products change at a faster rate than the fundamentals. Given that there is no such thing as a perfect amplifier your radio has some degree of internally generated distortion products.
>
> On Fri, 10 Jan 2025 23:08:06 +0000 (UTC)
> "Joseph K7CBR via groups.io" <k7cbr@...> wrote:
>
> >? OK. Just so we are on the same page, I need you to show me how you are measuring all this so I can too can see the empirical evidence and be convinced that this indeed is as critical as you say it is in the 2.1 to 2.8khz pass-band of my device? I can't weigh in on this until you explain and show me how you measured all this.
> > Joseph
> >
> >? ? On Friday, January 10, 2025 at 05:38:21 PM EST, Jim Shorney via groups.io <jimnu0c@...> wrote:?
> >?
> >?
> > And you are missing my point. Reducing the RF gain makes internally generated IMD products decrease faster than the desired signal. Which is entirely on topic for the usage of the RF Gain control. ACG attack distortion and IMD are certainly related but AGC is not the sole cause of internally generated IMD.
> >
> > On Fri, 10 Jan 2025 15:47:44 +0000 (UTC)
> > "Joseph K7CBR via groups.io" <k7cbr@...> wrote:
> >?
> > >? have you been checked for rabies? lol* read my whole note from 7:07AM ET. AGC/RF gain was my topic. I shall leave Drake IMD issues to manufacturers and other ops to try and conquer. Im running a 52 year old set of boxes. Run them as clean as I can (xmit/rcv). full stop...
> > >
> > > *asking this, could get me banned for life... hope not yet its A-OK...
> > > Joseph
> > >
> > >? ? On Friday, January 10, 2025 at 07:53:48 AM EST, Jim Shorney via groups.io <jimnu0c@...> wrote:?
> > >?
> > >?
> > > That is one aspect of the issue. Every amplifier has IMD whether gain controlled or not. It is a question of how much. It may be very little or it may be a lot but each stage contributes to the total.
> > >
> > > On Fri, 10 Jan 2025 12:05:42 +0000 (UTC)
> > > "Joseph K7CBR via groups.io" <k7cbr@...> wrote:
> > >??
> > > >? AGC attack distortion is the actual problem. Decreasing RF gain on low bands where the noise level remains high is what we are talking about???
> > >
> > >??
> >
> >
> >?
>
>
>



--

73

-Jim
NU0C