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On the most expensive unit the "Pro" model a remark seemed to
indicate that it's gain was dependent on PS voltage 10V to 18V.
BUT - that page is a mess of cut and paste. I don't know what you
really get with any of the packages. The specifications seem quite
On 20220709 23:34:50, Conrad, PA5Y
it? I don’t like that idea at all. The specifications say 5V
Frequency 88-108 MHz
Gain 10-18 dB variabel
Noise figure 0,30 dB
3dB BW typ MHz 70 MHz
Max. Outputlevel 119dB/µV
Input Return loss min -12dB
Output Return loss min -16dB
Connectors F-F Male
DC supply 5V@150mA
DC supply via Coaxcabel 5V@150mA
Dimensions 99X39X40 mm
It appears they require their own power supply with the gain
being controlled by the supply voltage.
On 20220709 12:01:14, Simon Brown wrote:
Please do a noise analysis for
88-108MHz. I think the S3 bias-t is 5v, not sure what
voltage these preamps require.
I could not agree more, a step
attenuator on the output is a good idea. You can of
course use the noise free bias tee on the S3 for the
supply. These are almost certainly PGA103+ LNAs. You
can use AppCAD and do a system noise analysis. If you
like I will do one and put it on here. In fact I may
have already done one and posted it some time ago. I’ll
have a look.
The cheapest one would probably be good enough. The
next one up might be slightly better because you get a
nice noisy power supply and (possibly redundant) Bias-T
tap for it. The most expensive one would only be needed
if you have some exceptionally strong signals nearby.
18 dB gain may be a little high with only 2.5 dB of
cable loss. Something like one of the old HP 1 dB step
variable attenuators might be good on the receiver
input. Adjust it for a suitable compromise for dynamic
range and signal strength. I suspect you do not need
this 10V version of the amplifier.
(Did I just save you a bunch of money?)
On 20220709 11:12:30, Simon Brown
I'll start saving and buy a
masthead preamp (below). My income is way down now
due to COVID and other cost of living issues. Not a
great time to be relying on donations.
They have a bit of input
filtering already, don't know if it's enough.
According to the user manual
with the preamp and noise reduction on the MDS at
91.1MHz is -138dBm in 500Hz, which equates to
-165dBm/Hz. This is a 9dB noise figure and is
probably 3-6dB worse because the NR makes things
appear better than they are. If you add 2.5dB to
that noise figure you can see that an LNA will be
of great benefit.
I suggest that a system noise
figure of around 2-3dB is optimum for Band II
What's the S3 noise figure
on Band II ? I have maybe 2dB loss in the 25m
RG6, so am wondering what the total NF is.
BTW I put the BPF before
the LNA to help protect it from 144MHz EME
high power. I am not suggesting that a PGA103+
will saturate from normal Band II situations.
However, it has a little bit too much gain, so
a good filter and an attenuator does no harm.
The S3 really is excellent. Just like you said
Hello Simon, I have done
a noise analysis and you WILL benefit from an
LNA. I have a PGA103+ preceded by a band pass
filter and it seems to work very well.
However, I am still waiting for a bigger
antenna. I ordered an OPTDES which never
arrived. So, I will ask a few of the local
Band II DXers for an alternative.
The ELAD S3 is the
best Band II receiver I have. Am thinking
about a preamp on the mast for those very
weak stations - if I get close to receiving
weak signals from across the pond (USA,
I have attached
3 pictures all with Console running.
The RSPdx is the
only on of these three that has a
decent signal. Running uno is fine
It is the other
two that are causing problems. The
native software yields the same lousy
signals. There is a lot of noise on
these two receivers for the station in
question. I have fiddles with the R2
slide controls in both Sharp and
Console. The Elad appears not to have
any RF gain capability.
The frequency I
am using for this exercise is 98.9, 92
watts, 25 km away. I am using the
same antenna for all three radios.
The antenna is pictured in an
attachment. Same feed line to all
three radios. My HF+ Discovery works
As I said in a
previous message, the Elad S2 is the
one that really puzzles me. I would
have expected it to come out the best
(based only on price, that is).
let me know if more information is
looking into this.
On Friday, July
8, 2022 at 11:38:57 PM PDT, jdow <jdow@...>
20220708 14:47:30, George Stein
- NJ3H via groups.io wrote:
92 watts not
Fri, Jul 8, 2022 at 2:24 PM,
George Stein - NJ3H via
to my last message. The
station in question is 25
km away and running a mere
Using SDR Console:
With the Elad S2 and and
the Airspy R2, the
reception was very noisy.
With the Airspy HF+
Discovery and the RSPdx,
the signal was full
quieting. With the edge
going to the HF+
This was not a scientific
test, just a casual
observation. The only
thing I am surprised about
was the Elad S2
I then used the native
software for each device
and had the same results.
Regards and YMMV,