Hi LEV Dave and the group,
Indeed your comment most true. I have decided that a preamp would be the
answer for me but to have the attenuator I mentioned in front of the Preamp. If
I have large signals making IMD I certainly wont need the extra gain and
dynamic range so attenuate it. If the signals are small they will not overload
the dynamic range and make IMD generally and the attenuator can be off. . The
attenuator in the Tiny SA is a menu item a bit unhandy to reach in the field.
And not much dB range.
This way the preamp wont have to be a power hog for high level signals. With
the tiny SA at about -100 dBm noise floor I am thinking adding a 1 to 2 dB
noise figure preamp which will increase the sensitivity without much added
noise over the common 18 to 22 dB you mention. Normally in a lab analyzer you
can adjust the sweep speed as well as the resolution bandwidth to get a lower
noise display. That’s not an option in the tiny SA. So, I will see how this
works.
Any way appreciate the comment as it definitely deserves some thought. .
Lee K7TJR OR
From: David Eckhardt <davearea51a@gmail.com>
Sent: Monday, April 12, 2021 4:49 PM
To: Lee STRAHAN <k7tjr@msn.com>
Cc: Dave Cole <dave@nk7z.net>; rfi@contesting.com
Subject: Re: [RFI] Flag Pennant loop - Tiny SA use
Don't forget the average 'lab' SA has a typical noise figure around 18 to 22
dB. All need a preamp for reasonable sensitivity. Many of the lab instruments
today are being marketed with a built-in preamp for this reason. Also, note
the dynamic range is degraded by the gain of the preamp. It's generally best
to have it present but easily bypassable for that reason.
Dave - WØLEV
On Mon, Apr 12, 2021 at 8:35 PM Lee STRAHAN
<k7tjr@msn.com<mailto:k7tjr@msn.com>> wrote:
Hi Dave and group,
I find the Tiny SA a little low on sensitivity so I am planning on adding an
external 20 dB preamp with an easier to use step attenuator for RFI hunting.
I have some other obligations at the moment so I am temporarily using an SI
4732 radio which is also a tiny box with AM.
I have the local power company and a wood products manufacturing company
working with me on an interesting conducted interference case I will eventually
report on here later after more tests.
Lee K7TJR OR
-----Original Message-----
From: RFI
<rfi-bounces+k7tjr=msn.com@contesting.com<mailto:msn.com@contesting.com>> On
Behalf Of Dave Cole
Sent: Monday, April 12, 2021 1:00 PM
To: rfi@contesting.com<mailto:rfi@contesting.com>
Subject: Re: [RFI] Flag Pennant loop - added benefit of being broadband
BTW:
I am currently working on setting up a tinySA on the FLAG... Try it, it is
really portable. The tinySA will mount right on the support pole for the FLAG.
No computer, no SDR, just a box the size of a pack of smokes...
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
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Dave - WØLEV
Just Let Darwin Work
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