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RE: [TenTec] Question regarding Omni VI+ on SSB

To: "Ten Tec List" <tentec@contesting.com>
Subject: RE: [TenTec] Question regarding Omni VI+ on SSB
From: "Jim Brown" <jim@audiosystemsgroup.com>
Reply-to: Jim Brown <jim@audiosystemsgroup.com>,tentec@contesting.com
Date: Thu, 25 Nov 2004 12:08:11 -0600
List-post: <mailto:tentec@contesting.com>
I've never owned a Jupiter, so this is an educated guess. I suspect it is a 
low-cut for the transmit audio. I would set it by ear listening to your 
transmit audio and by getting signal reports from smart guys on the 
other end, but somewhere in the 400 Hz range is probably a good 
starting point.  

Think of it this way -- anything below 400 Hz is useless for 
communications.  Telephones, for example, transmit nothing below 
about 400 Hz.   But your mic will produce a lot of audio below 400 Hz, 
and that will use up transmitter power. so filtering it out is a good thing. 

The guys on 14.175 would disagree with me. But I'm coming from my 
world of REAL pro audio, where the big music systems I design do 105 
dBSPL from 30 Hz to 15 kHz for 5,000 people. There's where wide 
audio bandwidth is needed -- not on the ham bands. 


On Thu, 25 Nov 2004 16:12:42 -0800, NJ0IP wrote:

>Jim that was a very informative and useful post.
>Perhaps you can answer another question of mine.
>What is the "TX Rolloff" on the Jupiter?
>It is a menu adjustment which goes from 0 Hz to 1270 Hz.
>I couldn't find any reference to it in the Jupiter manual.
>-----Original Message-----
>From: tentec-bounces@contesting.com [mailto:tentec-
>On Behalf Of Jim Brown
>Sent: Wednesday, November 24, 2004 7:40 PM
>To: tentec@contesting.com
>Subject: Re: [TenTec] Question regarding Omni VI+ on SSB
>On Wed, 24 Nov 2004 18:27:11 -0500, Jeff Frank wrote:
>>ll you guys who report about the great audio reports you receive on 
>>with the Omni 6 series please tell me what microphones or 
>>ups you are using. 
>Ah -- you bring up a very interesting defect in the design of the Ten Tec
>You can't use a "flat" mic with them, you need to use one that has a 
>high end. That's what the Heil mics do. A good mic sounds really dull 
>bassy on a Ten Tec radio. 
>I use an RE-27, which is a pretty flat mic (and a damn good one) with 
>But to make it sound good, I had to stick a rather small cap in series 
>to drastically roll off the low end (-3 dB at roughly 2 kHz). It is absurd
>that it 
>should be necessary to do that, but it is. This is a "band-aid," but it
>works. I 
>even have an audio file that NY9H recorded off the air several months 
>on 20 meters from Chicago, when I was operating this rig at W6BX, a 
>mile path. It's this mic, the cap, and the Omni V. I could email the file if
>anyone cares. 
>The Shure 444 and mics like it have the hyped high end that sounds 
>good with the Omni family of radios. I bought one for that reason. BTW 
>there's no good reason to spend money on a Heil mic to get that sound 
-- a 
>used 444, $30 on EBay, will sound at least as good as a Heil. For that 
>matter, I bought three Plantronics earsets for $5 each at a hamfest last
>They get MUCH better reports on my 746 than a Heil does on my K2.  
>can buy the Plantronics earsets (earphone plus mic) for $25 - $40 
>new at computer stores. 
>Now, you say, why in the world would you use an RE-27 on a ham rig?  
>Simple. I'm in the pro audio biz and own a lot of very good mics, but 
>dynamic mics. Also, most dynamic mics have proximity effect, which 
>the low end (makes them muddy) when you close-talk them).  I didn't 
have a 
>dedicated ham mic, needed one to use with the Omni V I had just 
>and the RE-27 came the closest to what should work well. It is a 
dynamic (I 
>only have three types) it  has no proximity effect because it is a
>cardioid, and it has a lot of output.  Isn't it serious overkill?  If I had
>to buy it, 
>yes. But if I have several laying around, no. 
>Jim Brown  K9YC
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