This was very interesting - the TinySA Ultra sounds like a great tool.
Checking online, I was surprised to find it for sale for as little as
$70 (Karagas), and as much as $140 (Rbay). In this era of unauthorized
cloning, I'm wondering if there is a way to identify a good one.
73, Pete N4ZR
On 9/15/2023 11:03 AM, Don Kirk wrote:
Hi Dave and gang,
The DXE preamp gain is approximately 30 dB (with its attenuators turned
off) until about 35MHz and then the gain drops like a rock above that point
so overload from VHF and above stuff is normally not an issue. Also down
on 160 meters the gain of the portable flag is -63 dBi and gets lower as
you go lower in frequency so this naturally helps attenuate strong AM
broadcast stations. On 30 MHz the portable flag gain is -19 dBi.
I just ran a quick test with my TinySA Ultra with its LNA on and the DXE
preamp inline and on with no attenuation selected and the AM filter turned
on and the strongest AM broadcast station was a station running 5 KW and
9.4 miles from my house on 1260 KHz and it measured -55 dBm. Strongest
signal received between 200 kHz and 5.3 GHz with DXE preamp AM filter
turned on was -40 dBm and it was from a shortwave broadcast station on
approximately 13.6 MHz. To prevent internally generated spurious emissions
on the TinySA Ultra I try to keep signal levels below -25 dBm. I also ran
a self test on my TinySA Ultra after the above tests and it passed with
flying colors.
The bottom line to avoid overload from AM broadcast stations when using the
TinySA Ultra with its LNA on when using the DXE preamp is to make sure the
DXE preamp AM broadcast filter is turned on but even in my tests today at
my QTH having the AM filter turned on was not necessary (also a good idea
to have the TinySA Ultra attenuator set to Auto). I measured the AM
broadcast station on 1260 KHz at -70 dBm using just the TinySA Ultra with
its LNA on when connected directly to the portable flag (DXE preamp not
connected) and it measured -37 dBm with the DXE preamp inline and on with
its AM filter turned off which is still well below the overload point on
the TinySA Ultra. Therefore unless you are very close to a high power AM
broadcast station or another very close in transmitter / source of RFI,
overload of the TinySA Ultra with its LNA on and the DXE preamp inline and
and on with the AM Filter selected is really not as likely as one might
think. I would not have the TinySA Ultra LNA on unless needed to see a
very weak signal, but this is normal regarding any receiver I'm using as I
also switch in attenuators as needed to keep the signal of interest under
the full scale reading of the S meter on my receiver as an example.
Just FYI, and 73,
Don wd8dsb
On Fri, Sep 15, 2023 at 8:43 AM David Eckhardt<davearea51a@gmail.com>
wrote:
With the preamp you purchased with the Flag antenna and the preamp built in
and selectable within the TinySA Ultra, you should have enough
gain/sensitivity to well overload the TinySA, unless you live in the middle
of nowhere with no cell coverage, no TV, no FM, no daytime AM radio,
and...... Yes, those places still exist here in the west.
Dave - WØLEV
On Thu, Sep 14, 2023 at 2:21 AM Jim Miller<jim@jtmiller.com> wrote:
I've got a TinySA Ultra and recently purchased the DXE Flag by WD8DSB and
Preamp. I'm wondering if the combination will be adequately sensitive or
should I use some other receiver?
Thanks
Jim ab3cv
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
--
*Dave - WØLEV*
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|