[1000mp] IM due to tuner in MkV

[J. C. Mc Laughlin]

Dear Clyde K9JWI:
    Yours is the most interesting message on the subject that I have 
received.  It sure would be desirable to know what the cause might be.  It 
is entirely possible that the previous owner abused the tuner and did not 
realize the consequences as he may well have spent all of his time on a 
couple of 75 meter frequencies.

Might you recall any other symptoms?  . . .  any other observations by 
WA4GEG?

If WA4GEG thought that "the situation was not uncommon," others on this 
group must have seen the situation - or they were just lucky not to have 
accidentally tuned with a "bad" load.    . . . which is probably what 
happened to you.

Thank you very much for coming forward.  You have provided particularly 
useful information.

73,    Mac   N8TT

J. McLaughlin;  Michigan, USA
Home:  JCM at power-net.net
----- Original Message ----- 
From: "Clyde" <k9jwi at comcast.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 8:20 PM
Subject: Re: [1000mp] IM due to tuner in MkV


> Mac,
>
> A couple of years ago my FT1000mp MK V exhibited
> behavior very similar to what you describe.  After
> fruitless attempts to find the problem, I sent it
> to Byron Campbell, WA4GEG.  He replaced the following
> parts:
> Q6453
> C6458
> C6459
> RL6451
> all TU-MAIN UNIT parts.
> He reported that the problem was likely caused
> by operating the tuner into an improper load
> (dead short or no antenna connected), and that
> the situation was not uncommon.
>
> Checking/replacing parts in the TU-MAIN UNIT is doable
> but not trivial.  I would send the radio to Byron in
> spite of the wait (he was busy) and the high shipping
> costs.
>
> Good luck and 73,  Clyde K9JWI
>
>
>
> On Sun, 2010-05-30 at 22:02 -0400, J. C. Mc Laughlin 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
>>