toggle quoted messageShow quoted text
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
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 DXing.
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
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 also.
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 fine also.
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).
Anyway, please let me know
if more information is needed.
Thanks for looking into
On Friday, July 8, 2022 at
11:38:57 PM PDT, jdow <jdow@...>
14:47:30, George Stein - NJ3H via
92 watts not
On Fri, Jul 8,
2022 at 2:24 PM, George Stein - NJ3H
Further to my
last message. The station in
question is 25 km away and running a
mere 25 watts.
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
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
Regards and YMMV,
- + - + -