[1000mp] IM due to tuner in MkV

[J. C. Mc Laughlin]

Dear Mike W2AJI:    Oh my!  If the tuner is supposed not to be in the signal 
path on receive then something significant is wrong.

Asserting the tuner (pushing the tuner button) obviously does something.  I 
wonder if it is that "something" causing the problem.  Might the tuner have 
a separate uP?  If so, it could be that for some hard-to-understand reason 
signals from the tuner's uP are being injected in the signal path.  If 
strong enough, such internally generated signals could cause the symptoms 
when driving the first active device bonkers.

Your observation about the tuner not being in the signal path on receive 
opens up the thought process.  Thanks.

73,   Mac   N8TT

J. McLaughlin;  Michigan, USA
Home:  JCM at power-net.net
----- Original Message ----- 
From: "Mike Schatzberg" <cherokeehillfarm at earthlink.net>
To: "J. C. Mc Laughlin" <jcm at power-net.net>; "All about Yaesu 1000mp" 
<1000mp at mailman.qth.net>
Sent: Monday, May 31, 2010 8:33 AM
Subject: RE: [1000mp] IM due to tuner in MkV


The tuner is not in the signal path at all unless the radio has had major 
modifications.

Mike
W2AJI

-----Original Message-----
From: J. C. Mc Laughlin <jcm at power-net.net>
Sent: Monday, May 31, 2010 8:20 AM
To: Roy Westra <rpwestra at gmail.com>
Cc: 1000MP Dec2001 <1000mp at mailman.qth.net>
Subject: Re: [1000mp] IM due to tuner in MkV

Dear Roy AA6QQ:

    It is not a matter of the time of day.  The SW broadcast stations are
heard on indicated frequencies that are way different than the actual
frequency of the SW broadcast station (and multiple other places).  In other
words, a strong non-linearity is at work.   The FT1000 is far away from
ground wave reception and yet the phantom signals are received as being very
strong.

    I am not clear about "various filters."

    It is not clear whether the non-linearity is before the first IF filter
(the so called roofing filter).  Since the tuner is between the first IF
filter and the antenna port, it is expected that the non-linearity is prior
to the first IF filter.

    Note that an old, tube type receiver connected to the same antenna does
not hear the phantoms.

    Thanks for your ideas.    73,   Mac   N8TT
J. McLaughlin;  Michigan, USA
Home:  JCM at power-net.net
----- Original Message ----- 
From: "Roy Westra" <rpwestra at gmail.com>
To: "J. C. Mc Laughlin" <jcm at power-net.net>; "All about Yaesu 1000mp"
<1000mp at mailman.qth.net>
Sent: Sunday, May 30, 2010 11:27 PM
Subject: Re: [1000mp] IM due to tuner in MkV


> Hi Mac,
> At what time of day does he hear these stations? Sometimes I hear
> shortwave
> broadcast stations early in the morning on 40 meters but they go away
> later
> as the band warms up. If that's not the problem has he tried using
> the various filters to block them out? Also Inrad Inc. (
> http://www.inrad.net/home.php?xid=692b5e4d46838cf39b9c7574f3762a35) has an
> IM mod and also sells roofing filters.
> Roy
> AA6QQ
>
> On Sun, May 30, 2010 at 7:02 PM, J. C. Mc Laughlin
> <jcm at power-net.net>wrote:
>
>> Dear group:
>>
>> A colleague of mine just bought a used FT1000 MkV (200 watt version).  He
>> found significant IM on receive when the tuner is asserted.  That is to
>> say,
>> short wave broadcast stations appear to be way out of their band.
>>
>> I speculate that a non-linearity exists somewhere in the tuner.  Could be
>> a
>> corroded relay contact or a cold solder joint.
>>
>> Has anyone had this experience?  If so, what did you find and what was
>> the
>> cure?  Thank you.
>>
>> 73,    Mac    N8TT
>>
>>
>> J. McLaughlin;  Michigan, USA
>> Home:  JCM at power-net.net
>>

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