You ask my question more clearly.
Joe, N4YG
----- Original Message -----
From: "Barry N1EU" <barry.n1eu@gmail.com>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Monday, September 19, 2011 6:40 AM
Subject: Re: [TenTec] Broadcast Interference Fix for the Corsair II
> From the description of the mod in the posting, it seems like a
> worthwhile mod. I was wondering:
>
> 1. Has anyone pulled the 80969 LPF-TR board and can describe what's
> involved/how difficult a task it is?
> 2. Why is the schematic marked "optional hi pass not installed" in
> the section that contains the junction of C7, L9, and L10. (new
> connection for Q2 collector)? Is the hi pass filter actually present
> despite that notation?
>
> 73, Barry N1EU
>
> On Sun, Sep 18, 2011 at 10:14 PM, Joe <joe@n4yg.com> wrote:
>>
>> Below is a posting I was so pleased to find in my search to find a
>> solution for Broacast Radio Interference and hash on all bands of my
>> Corsair II. I am anxious to try this fix but I the task of getting to the
>> transistor Q2 seems to be almost impossible. I want to talk to Rick,
>> WA6NCX, but I have not been able to get up with him. Failing that, I
>> would like to talk to someone who has completed this fix. I fear that if
>> I am not careful here I will do something that I will regret. I would
>> appreciate any help.
>>
>> Joe, N4YG
>>
>>
>> WA6NCX posting 24 Aug 2000Subject: [TenTec] Broadcast Interference Fix
>> for the Corsair III heard tremendous hash on 160 - 40 meters whenever I
>> hooked my Corsair II to
>> a big 80-meter full-wave horizontal loop. The problem was traced to
>> overload of
>> switch transistor Q2 on the 80969 LPF-TR board. The transistor junctions
>> were
>> rectifying a strong local BC station (putting over a volt of rf into the
>> receiver!), whose
>> signals passed right through from the antenna to the SWR detector and
>> xmtr LPF's,
>> through the TR switch diodes and then into the Q2 collector without any
>> help from
>> the rig's BC-reject high-pass filter network (the transistor is connected
>> *before*
>> the high-pass filter).
>>
>> After fooling around with a few false starts (which TT helped with, but
>> didn't solve),
>> it dawned on me that the fix is to connect the Q2 collector *after* the
>> BC band high
>> pass filter network, so that the strong BC station signal is greatly
>> attenuated before it
>> gets to the Q2 collector. So all I did was cut the trace to the Q2
>> collector and run a
>> short wire from the Q2 collector to the output of the BCB reject
>> high-pass filter,
>> right at the "RX" connector on the 80969 circuit board (at the junction
>> of C7, L9,
>> and L10). This fixed the problem completely -- no more hash and nice
>> quiet reception
>> on 160 through 40 meters.
>>
>> -- Rick WA6NCX
>> remler@juno.com
>> _______________________________________________
>> TenTec mailing list
>> TenTec@contesting.com
>> http://lists.contesting.com/mailman/listinfo/tentec
>>
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|