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Re: [TenTec] 2800Hz filters in 9mHz slots?

To: tentec@contesting.com
Subject: Re: [TenTec] 2800Hz filters in 9mHz slots?
From: Jim Brown <k9yc@audiosystemsgroup.com>
Reply-to: k9yc@arrl.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sun, 19 Jul 2015 10:56:56 -0700
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
On Sun,7/19/2015 10:02 AM, Barry N1EU wrote:
Yes, it will improve transmit fidelity.

The words "improve transmit fidelity" in this context are mis-applied. This is ham radio, and our objective is COMMUNICATION, not wider audio bandwidth. Lower audio frequencies (below about 500 Hz) make almost no contribution to speech intelligibility, but burn almost half of transmit power. A smart ham will cut off those low frequencies to provide better "talk power."

I don't know who makes those filters, but the Elecraft filters come from Inrad. The stock Elecraft TX filter is 2.7 kHz, 5 poles. The "upgrade" is 2.8 kHz, 8 poles. The 2.8 kHz filter is flatter in the passband than the 2.7 KHz filter. The difference shows up in reduced incidental AM when transmitting RTTY and smoother audio response on SSB. I have 2.8 kHz filters in my K3s.

73, Jim K9YC
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