Date: Wed, 3 May 2023 10:11:54 -0700
From: Jim Brown <jim@audiosystemsgroup.com>
To: amps@contesting.com
Subject: Re: [Amps] Tiny SA ultra, part 2@audiosystemsgroup.com
<68da6a57-1631-02df-034b-169f4e74f139@audiosystemsgroup.com>>
Content-Type: text/plain; charset=UTF-8; format=flowed
On 5/3/2023 4:17 AM, jim.thom jim.thom@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
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