[TenTec] Broadcast Interference Fix for the Corsair II

[Rick - DJ0IP / NJ0IP]

Of course there is another way to fix the problem without digging into the
rig, but it's not exactly cheap.

Dunestar makes a highpass filter, model HPF-400 which you can simply insert
in the antenna line, right at the transceiver. This external HPF will drop
the signal level of the disturbing broadcast station and can be left inline
all the time, but it will cost you $99 plus shipping.

For more info, see: http://www.dunestar.com/model400.htm 

73
Rick, DJ0IP


-----Original Message-----
From: tentec-bounces at contesting.com [mailto:tentec-bounces at contesting.com]
On Behalf Of Joe
Sent: Monday, September 19, 2011 4:14 AM
To: TenTec Discussion
Subject: [TenTec] Broadcast Interference Fix for the Corsair II

 
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 at juno.com
_______________________________________________
TenTec mailing list
TenTec at contesting.com
http://lists.contesting.com/mailman/listinfo/tentec