[Amps] Alpha 87 (not 87A)

Jim Thomson jim.thom at telus.net
Wed Nov 8 14:03:47 EST 2017

##  That will only work.... provided there is nobody within 6 khz of you.
In the example I used below, if you are listening on  3800..and switch to
USB,  you will then hear everything from 3800 to 3803.   If a 3rd fellow 
to be transmitting LSB on 3803,  you will then hear  the 3rd fellow full 
Even if he is on 3806, transmitting LSB,  you will still hear his 
3806..down to
3803 LSB signal.   So the opposite  sideband  RX works..but with caveats.
In any contest, you are very unlikely to have nobody within 7-10 khz above
your freq on 160, 75m or 40m.    Or  7-10 khz below you on  20, 15, 10 m.

##  Interesting enough, a bunch of us tried that on 75m, while using ESSB, 
and 5.7
khz  wide TX... using modified 1000-MP-MK-Vs.  I cant hear anything on the 
sideband of  several  friends identically modified MK-Vs.  And they are 
loud.   But when the ICOM
756 Pro 2 and 3 folks start TXing,  I can hear all sorts of crud on the ICOM 
rigs..go figure.  Its
to the point where I can usually tell what brand xcvr they are using..and 
which model !
Hi Bob, how is your icom 756 Pro-3  working out for you ?   How did you know 
I was using a Pro-3 ?
Cuz it has a distinct  sonic signature, a mixture of ....digital grunge and 
unique imd products.

##  IF you try and monitor your own signal, using a 2nd xcvr, switched to 
the opposite sideband,  only
a short 3 to 6 inch long pigtail is required  for the RX ant.   That plus 
loads of RX padding employed,
RF gain control backed way down,  RF pre-amp shut OFF, NB OFF  etc, etc.

Jim   VE7RF

-----Original Message----- 
From: Gary Schafer
Sent: Wednesday, November 08, 2017 10:21 AM
To: 'Jim Thomson' ; amps at contesting.com
Subject: RE: [Amps] Alpha 87 (not 87A)

The easiest way to observe splatter is to switch your receiver to the
opposite side band and listen for the crud.
Intermod products are generated on both sides of the signal. By listening on
the opposite side band you eliminate your receivers filter bandwith from
causing you false indications.

On a good clean signal you will not hear anything on the opposite side band
from that station.

Gary  K4FMX

> -----Original Message-----
> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Jim Thomson
> Sent: Wednesday, November 08, 2017 10:44 AM
> To: amps at contesting.com
> Subject: [Amps] Alpha 87 (not 87A)
> Date: Tue, 7 Nov 2017 15:14:43 -0500
> From: Larry <pacer99 at aol.com>
> To: jim at audiosystemsgroup.com, amps at contesting.com
> Subject: Re: [Amps] Alpha 87 (not 87A)
> <jim,
> <i just finished the CQ WW SSB and except for a very few stations the
> quality of signals was good. i am using an Icom IC-7800.
> <i believe that if each of us take the time to contact the offending
> station and explain, in a polite manner that they were "spattering".
> try to help them correct the problem. the bands would clean up rapidly.
> every time that i do it the problem is solved and the <offending station
> is grateful. no one wants to be rude to others. it's a friendly hobby
> after all.
> <complaining does no good.
> <73,
> <larry
> <n7dd
> ## For folks trying to measure the total BW of an SSB  signal,  remember
> not to inadvertantly  add the width of your RX filter...to the other
> fellows TX bw.   IE: say you are using a 3 khw wide RX filter..and are
> on 3800 LSB.   You will hear
> everything from 3800...down to 3797.   Meanwhile the offending station
> is on  3797 LSB.  Assume he is also TXing with a 3 khz filter.  On
> paper, he should be occupying  3797...down to 3794.   You tune across
> his signal, and you can hear
> him from   3794....all the way up to  3800.    You tell the fellow that
> you can hear him.. 3 down...and  3 up from his TX freq of 3797.  No the
> fellow is not 6 khz wide,  he is only 3 khz wide.   You have added your
> 3 khz wide RX BW  to his
> 3 khz TX BW to arrive at the 6 khz figure.... which is incorrect.
> That mistake is done all the time.  A better method  would be to  tune
> across his ssb signal, using a  pair of 500 hz cw filters..... sorta
> like  poor mans  spectrum analyzer. In actual
> practise, it works good.   Then you will hear that he is only 3 khz
> wide.
> ##  I wouldnt put any stock in the Icom fish finders either.  They will
> easily show a dead cxr as being 2 khz wide, and other erroneous stuff.
> Also make sure your NB is OFF, and dont have excess RF gain applied.
> Shut the RF rx pre-amp off, NB
> off, and back down on the RFor IF gain control a bit..and also switch in
> some RX padding, like  6 or 12 db.   Then use a pair of 500 hz filters
> if using a xcvr that has switchable  RX  CW filters, or the dsp eq....
> then carefully tune across his signal,
> using your MAIN RX.   Meanwhile you can  simultaneously listen on 3797
> LSB... on your SUB  RX.   Then you can correlate asap,  any splatter
> products, while listening on your Main RX..with a pair of 500 hz cw
> filters in left ear... while listening to him on LSB... on your right
> ear....using the sub RX.
> Jim   VE7RF
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