[ICOM] Overload, 756 PRO III (Was Comments on 746pro)

[W7RY]

I have not measured the second harmonic attenuation of the receiver band
pass filter in a 756 PRO. But my guess is that it's at least 40-50 dB.
The distance between W1 and W4 is 400-500 miles away.  How strong does
the signal need to be to overload a receiver on the second harmonic?
VERY strong. But if the transmitter had a large 2nd harmonic content, it
would be easy to hear.


73
Jim W7RY



-----Original Message-----
From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net]
On Behalf Of Larry Benko
Sent: Monday, February 06, 2006 9:11 PM
To: ICOM Reflector
Subject: Re: [ICOM] Overload, 756 PRO III (Was Comments on 746pro)

David,

Perhaps it was his problem (a real harmonic) and perhaps it was your 
reciever (overload, IMD etc.).  The simple test is to put some real 
passive attenuation in front of your receiver such as a 20dB Tee or Pi 
type resistive pad.  If the offending signal disappears then it is an 
artifact of your radio but if it is still there, but of course 20dB 
weaker, it is a real harmonic.  Usually a 10dB pad is enough to show the

difference but I think 20dB works better if the offending signal is at 
least S5 or so.

73,
Larry, W0QE

David J. Ring, Jr. wrote:

>Using my IC756PRO I heard one W4 on 3700 kHz area - he was actually on
160 
>around 1830 or so.  I tuned up on 160 and told him about it, but I
heard no 
>others leaking through.
>
>73
>
>David N1EA
>
>----- Original Message ----- 
>From: "W7RY" <w7ry at centurytel.net>
>To: "'ICOM Reflector'" <icom at mailman.qth.net>
>Sent: Monday, February 06, 2006 11:30 PM
>Subject: [ICOM] Overload, 756 PRO III (Was Comments on 746pro)
>
>
>I too noticed images on my NEW pro III on 160 meters during the CQWW CW
>contest. Needless to say, I was very disappointed to here them on a rig
>I just paid $3000.00 for.
>
>According to Adams web site, the 756 pro III is better than anything
>else!
>
>Hmmmmm....
>
>
>73
>Jim W7RY
>
>
>
>
>-----Original Message-----
>From: icom-bounces at mailman.qth.net
[mailto:icom-bounces at mailman.qth.net]
>On Behalf Of Bob Garrett
>Sent: Sunday, February 05, 2006 8:06 PM
>To: ICOM Reflector
>Subject: Re: [ICOM] Comments on 746pro
>
>Gary et al,
>
>I purchased the 746PRO in November of 2004, my first Icom rig.  I then
>purchased the 756PROIII in March of 2005.  I really liked the 746PRO
and
>
>thought hmmm, if the 746PRO is good, the PROIII has to be significantly
>better.  Yes, the RX is quieter but, for the investment, the 746PRO is
a
>
>better value.  I find both suffer from phantom signals.
>
>Let me quickly add that about 95% of my operating is on 160 meters
>chasing
>DX where you have 20 over S9 signals and you are trying to dig out a S4
>signal close by.  The only rig I have found to date that is pretty much
>bullet proof under those conditions is my FT-1000MP Field with the
Inrad
>
>roofing filter.   I do switch between all three rigs frequently and
each
>has
>its strong and weak points.
>
>Just one mans opinion.
>
>73, Bob K3UL
>
>----
>Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
>Icom Users Net: Sundays, 1700Z, 14.316 MHz
>Icom FAQ: http://www.qsl.net/icom/
>
>
>----
>Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
>Icom Users Net: Sundays, 1700Z, 14.316 MHz
>Icom FAQ: http://www.qsl.net/icom/
>
>
>  
>

----
Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
Icom Users Net: Sundays, 1700Z, 14.316 MHz
Icom FAQ: http://www.qsl.net/icom/