[karc] Re: So-called sub-audible tones
- From: Max Donoghue <ve3tmt@xxxxxxxx>
- To: karc@xxxxxxxxxxxxx
- Date: Mon, 12 Oct 2009 06:05:02 -0700 (PDT)
Phil,
I hear them as well on the TS-2000. I dial the DSP low cut up to 200 hz and all
is well.
Max
VE3TMT
________________________________
From: Phil Somers <pwsomers@xxxxxxxx>
To: KARC FreeList <karc@xxxxxxxxxxxxx>
Sent: Sun, October 11, 2009 8:27:10 PM
Subject: [karc] So-called sub-audible tones
Ever wonder why they are called "sub-audible" tones? Your ear has been hearing
60 cycle (60 Hz) hum for years. Why wouldn't it be able to hear 151.4 Hz? Well,
of course it can. Apparently VHF receivers are designed with filters that block
from about 67 Hz to 254.1 Hz, some better than others. My IC-746PRO is
primarily an HF rig but also includes 6m and 2m. On 2m FM, it does not filter
out these low frequencies. They are easily discernible as a low hum, for
example when I am listening to the 94 repeater or the input on 34 where users
are also using 151.4. VE3DZE, VA3AKY and I just did some tests on 52 with and
without tones, and tones from the low end 67 Hz to the top end 254.1 Hz. Big
range of responses from various rigs. On some rigs, the 254.1 tone was very
loud and annoying.
So if you are hearing some "hum" on the repeater, but not on direct on 52,
etc., it may well be the so-called sub-audible 151.4 tone.
... Phil VE3HST
________________________________
Looking for the perfect gift?Give the gift of Flickr!
__________________________________________________________________
Get a sneak peak at messages with a handy reading pane with All new Yahoo!
Mail: http://ca.promos.yahoo.com/newmail/overview2/
Other related posts:
