[TenTec] 250Hz Roofing Filter

Duane Calvin ac5aa1 at gmail.com
Mon Jun 10 19:03:25 EDT 2013

	Was the extra amp section also used for the 500 Hz filter, or just
the 250 Hz?  Just wondering.


Duane Calvin, AC5AA
Austin, Texas

-----Original Message-----
From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Zivney,
Sent: Monday, June 10, 2013 5:54 PM
To: je2uff at gmail.com; tentec at contesting.com
Subject: [TenTec] 250Hz Roofing Filter

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
TenTec mailing list
TenTec at contesting.com

More information about the TenTec mailing list