Len,
I have used a small cap connected to the mixer output on a couple of
boat anchors and fed that signal into my 756 PROII. At the 455 kHz IF
of the boat anchors you don't get a lot of bandwidth due to the two
tuned RF stages. The size of the cap should be a few pf. This does not
have any effect on the boat anchors. You could probably grab the signal
at the input of the first (roofing) filter. The smaller the cap, the
less signal you get. With the sensitivity of the 756 you may be able to
use a small insulated wire taped to the circuit board trace.
The old Hallicrafters scope had stagger tuned circuits one above and one
below the IF frequency to flatten the response.
I also use a small cap to grab the HFO signal at the 1st mixer and send
it to a frequency counter. I use a variable cap and adjust from minimum
capacity until I get a reliable reading.
After the coupling cap you can use small coax to carry the signal. You
MAY get a small degradation in performance when you carry the signal
outside the shielded area. For instance you could couple around the
roofing filter.
Good Luck,
Barry
-----Original Message-----
From: tentec-bounces@contesting.com
[mailto:tentec-bounces@contesting.com] On Behalf Of Len Umina
Sent: Monday, August 08, 2005 2:37 AM
To: Tentec@contesting.com
Subject: [TenTec] 9 MHz IF Bandscope for Orion
I graduated from an ICOM 756 Pro 2 to a Tentec Orion. Although the
Orion does have some issues, particularly when the bandscope is active,
the radio is far superior to the ICOM on Receive (in fact it's better
than the 7800 in crowded conditions).
I still have the 756 Pro 2, and it appears that its possible to bring
out the 9 MHz IF from the Tentec, and use the ICOM as a bandscope for
the Orion. Of course any of the less expensive ICOM radios would make
excellent bandscopes too.
Has anyone tried doing this?
I've had a hard time with the schematics, the wiring isn't clear, and
the signal names (what signal names?) are not easy to follow, but it
looks like the signal is available. I'm going to try it this week
myself, and if no one has any data on the subject I'll post my results
here.
If the Orion can support this connection, the result is that SWEEP can
be kept off (which fixes a number of the related 'processing time'
problems) and the nice color display of the 7856 can be used to show the
band (about 70 Khz worth of it anyway).
73,
Len
WT6G
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