The Orion 565 (aka Orion I) uses 250 and 500Hz filters previously used in the
Omni line.
The Orion II 566 uses 300 and 600 Hz filters with lower loss and slightly
different frequency so doesn't have the
extra amplification stage that is in the 565 Orion. Using the Inrad 600 Hz
filter in the Original Orion has a different center frequency than the 250 and
500 Hz filters and doesn't use the extra amplifier, so doesn't have the extra
noise.
Terry N4TZ
________________________________
From: michael.cheponis@gmail.com [michael.cheponis@gmail.com] on behalf of
Michael Cheponis [Michael@Cheponis.Com]
Sent: Monday, June 10, 2013 7:49 PM
To: Zivney, Terry
Subject: Fwd: [TenTec] 250Hz Roofing Filter
Hi are you also saying or implying that the 600 Hz Ten-Tec filter also has the
extra IF amp and therefore extra noise?
Also, we're talking about quite low frequencies here --- couldn't the extra IF
amp be replaced by one designed properly (to overcome the additional loss of
the more-narrow filters, presumably)?
Thanks!
Mike
---------- Forwarded message ----------
From: Zivney, Terry <00tlzivney@bsu.edu<mailto:00tlzivney@bsu.edu>>
Date: Mon, Jun 10, 2013 at 3:53 PM
Subject: [TenTec] 250Hz Roofing Filter
To: "je2uff@gmail.com<mailto:je2uff@gmail.com>"
<je2uff@gmail.com<mailto:je2uff@gmail.com>>,
"tentec@contesting.com<mailto:tentec@contesting.com>"
<tentec@contesting.com<mailto:tentec@contesting.com>>
Hi Toshi
The Orion 565 has an extra IF amplifier for the narrow 250 Hz Roofing filter,
which adds noise.
Testing reported in QST showed that the dynamic range was worse with the 250 Hz
filter than with the wider filters because of this extra amplifier.
A common solution used in the USA is to substitute a 600Hz roofing filter from
International Radio (INRAD) in place of the standard 1,000 Hz roofing filter
and use that instead of the 500 and 250 Hz roofing filters. Most of us have
found that that 600 Hz filter is adequate for even the most demanding contest
operation.
Terry N4TZ
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