[Moon-Net] IQ+ PREAMP GAIN NEEDED

Paul Andrews w2hro.fn20 at gmail.com
Thu Nov 3 22:45:36 CET 2016


Serge,

I think I have the same 2M receive setup as you.   I have dual
polarization antennas (XP28s) and I use the dual channel IQ+ for
adaptive receive feeding MAP65.    I am using WA2ODO high gain (30 db
gain) preamps and 3db splitters to feed my 2M transceiver.  I use WSJT
v10 and sometimes v9.7 for a sanity check.  My transceiver soundcard
is SignaLink.   My IQ+ soundcard is Delta44.   My WSJT v10 runs on a
Win7 PC with i7 CPU.   MAP65 runs on WinXP with older Core2Duo CPU.

I was using an FT-847 but will soon be using a TS-2000X.   I have a
manual switch to feed RX-V or RX-H directly to the transceiver.   I
can also use a manual switch to select TX-V or TX-H.  MAP65 helps me
decide which is best.

I have an uncalibrated version of Linrad but it does not improve the
receive performance of MAP65 because I do not have an impulse noise
problem and my linrad is not calibrated.  :)

----------------------------

Summary - After my 1000+ QSOs on 2M EME during the past year - I am
very often surprised by which system decodes first but I'm learning
why this happens.  MAP65 will decode first if my transceiver is on the
wrong polarization.   IQ+ MAP65 will decode first if the receive
signal is sitting at 45 degrees (-3db).   When the receive signal is
pure V-pol or pure H-pol WSJT will sometimes report a better signal
than MAP65.

For some reason I am always very happy when IQ+/MAP65 and WSJT v10
report the same signal level because that means (to me) that the IQ+
is set up properly.

My FT-847 has AGC that can not be defeated without modifying the
radio.   The IQ+ has no AGC and is an excellent receiver for reporting
station noise floor issues.   I have a better 2M EME station because
the IQ+ doesn't lie to me.    If the IQ+ is happy - I'm happy.    If
the IQ+ is happy - MAP65 reports decoded signal reports at very
similar levels to WSJT during Co-Pol receiving.

IMHO - WSJT v10 has the advantage when I'm trying to dig out very weak
traces using Tol 10 Hz.     In my system, I see a significant decode
performance improvement when using Tol 10 Hz or 25 Hz.   Using Tol 10
/ 25 Hz on MAP65 does not seem to provide the same magic.

I'm a believer that WSJT v10 and MAP65 decode with equal performance
given an equal signal.  I am also convinced after a 1000+ QSOs and a
1000+ hours of operation that setting up MAP65 / IQ+ / Preamps /
Splitters / Delta44 and all the associated cables is more susceptible
to noise issues.

My cards are on the table.  Read'em and weep.

73 - Paul - W2HRO   (soon to be QRV - 23cm QRP)























On Thu, Nov 3, 2016 at 4:36 PM, serge <ve1kg at eastlink.ca> wrote:
> Les i have private emails of people who have the same problem as i have with
> the IQ+ & MAP65.  i am not alone.
> My system is very simple: Preamp to a 90 FT of over kill coax & a Splitter
> one side goes to IQ+ the other side goes to my 40 years old transceiver.
> That is it.
> My system works VERY well i am just intrigued why MAP65 & IQ+ does not
> decode as well as WSJT & My 40 years old receiver that is all.
> I will do the test that Leif suggested & i will have a better idea on what
> is going on.. Some people have added small rf amplifiers to make up for the
> losses & to get enough gain to the IQ+.
> I do not use Linrad it is above my level of comprehension so i accept the
> fact that i have reached my level of incompetence. Having said that even
> with my somewhat messy set up as you described it I do not miss too much off
> the moon.
> See you off the moon hopefully
> 73 Serge VE1KG
>
> ----- Original Message -----
> From: Les Listwa
> To: moon-net at mailman.pe1itr.com
> Sent: Thursday, November 03, 2016 7:22 PM
> Subject: Re: [Moon-Net] IQ+ PREAMP GAIN NEEDED
>
> Serge,
>
> There is a less costly alternative to running WSJT and Map-65 at the same
> time, especially in your case where you are horizontal only and can not
> take advantage of adaptive polarization.  Right now you are using your Icom
> for WSJT and the fabulous IQ+ for Map-65 and its  a complicated mess, with a
> splitter, an addtional relay(?),  and coax  adding additional losses, which
> requires more gain from the preamp, which you dont have unless you replace
> it.
>
> Learning from W3SZ,  I  use my IQ+ to "drive"  both Map-65 and WSJT at the
> same time using the magic of Linrad and VAC with the help Trackbox for
> frequency control. No 2nd receiver or additional hardware needed.
>
> 73
> Les
> W2LPL
>
> ________________________________
>
> _______________________________________________
> Moon-Net posting and subscription instructions are at
> http://www.nlsa.com/nets/moon-net-help.html
>
>
> _______________________________________________
> Moon-Net posting and subscription instructions are at
> http://www.nlsa.com/nets/moon-net-help.html
>
>


More information about the Moon-net mailing list