[Amps] Tiny SA ultra, part 2

[jim.thom jim.thom@telus.net]

Date: Wed, 3 May 2023 10:11:54 -0700
From: Jim Brown <jim at audiosystemsgroup.com>
To: amps at contesting.com
Subject: Re: [Amps] Tiny SA ultra, part 2 at audiosystemsgroup.com
<68da6a57-1631-02df-034b-169f4e74f139 at audiosystemsgroup.com>>
Content-Type: text/plain; charset=UTF-8; format=flowed

On 5/3/2023 4:17 AM, jim.thom jim.thom at telus.net wrote:
> This version might
> just work for imd testing.

<I haven't looked at the link, but the relevant spec is frequency
<resolution in Hz. And the relevant measurement is NOT the traditional
<2-Tone test, but the occupied bandwidth, measured by accumulating peaks
<over a period of time with a series of dits around 30 WPM, or speech, or
<RTTY.

<73, Jim K9YC

##  Freq resolution on the original Tiny SA (2.8" screen) is just a minimum
of 3 khz.

##  One the updated Ultra version (4.0" screen)   resolution is now down to
200 hz.

## Several folks told me that the Tiny SA was useless for IMD testing, due
to it's 3 khz resolution.   Apparently somebody listened, and the newer /
bigger version, with it's 200 hz resolution, should fare better.

##  yes, I know the 2 tone has limitations.  Like  2 tone results can
easily be skewed by simply tweaking the tone spacing.  With a 2  tone,
everything is in a steady state, including  drive levels, PO, ALC,  bias,
B+ / Vdc  etc, etc.

##  I have experimented with pulsed 2 tones, and also a 3 tone, and also
white + pink noise, and also plane  speech.   The white + pink noise works
pretty good, albeit it also renders everything in a steady state.

## I would also want to use the SA to measure harmonic attenuation on some
of my many HB / modified commercial amps.   One of the G stations on FB
built a hb attenuator in a box, then added an additional BNC attenuator on
the BNC output to the  SA.  A pair of SO-239's used for the amp in
/out..then to a DL setup.   Worked superb on his HB tube amps..and that was
using the Tiny SA..with it's 2.8" screen..... which of course won't work
with IMD testing.

## heck, this ultra version even has the waterfall display + SA....one or
the other, or both.   It also has a RF signal gen built in.   One of the
pundits was comparing it to his lab grade gear at work..and it fared pretty
good.  Huge improvement over the original unit.

Jim  VE7RF