A monitor scope such as the Heath SB-610 is almost a must in my book. Yet
today very few hams have or even use one. And of course, knowing what a
clean signal looks like is always a big help too. I guess we are delegated
to a bunch of "plug n play" operators.
I don't understand the "only use low power" comment. If need be, I can run
near legal limit power, AFSK or PSK or FSK without any problems or concerns.
IMD values on PSK are in the upper 20's to 30 dB range at 1200 watts output.
Of course if the audio is distorted before going into the radio or plagued
with RF or has hum or overdrives the input stage then the old adages of
"garbage in = garbage out" is in full force.
Try measuring the THD+n value of the signal coming out of the sound card. I
think you'll be surprised as to how much garbage is actually present in that
signal. Running that signal through some interface box with poor quality
transformers or transformers which are poorly damped certainly doesn't help
either. An interface powered by a poorly filtered "wall wart" adds more
crud to the signal and all this takes place before it gets to the radio.
I've found that it takes patience, understanding, knowledge and skill, plus
several hard earned dollars, to put together a system that is always clean
in all aspects. The result is well worth it however.
73
Bob, K4TAX
----- Original Message -----
From: "Roger Hughes" <roger.h@comcast.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Monday, January 26, 2009 10:18 PM
Subject: Re: [TenTec] Omni VI Mod 3 and RTTY
FSK Was not that hard for me. The problem with AFSK is it can easily
overdrive.Only can use low power. I use both fsk and afsk. It you do PSK
with afsk be careful. Find out what IMD means.... It's unbelieveable what
you can see on psk freqs. A lot of hams have no to very little education on
that and many other things.Just look how wide the signals are.I guess they
watch other people and learn most things over their local repeater from hams
that never even done psk or rtty.but that's todays ham. 73 Gud luck,, w4iv
Roger. Original Message -----
From: "Gary Hoffman" <ghoffman@spacetech.com>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Monday, January 26, 2009 9:32 PM
Subject: Re: [TenTec] Omni VI Mod 3 and RTTY
People will tell you that AFSK can be set up badly, so as to splatter and
make a mess. That's true.
But then again - so can FSK.
I'd do AFSK cause its so much easier....but take the time to learn how to do
it right and make sure to do so.
73 de Gary AA2IZ
----- Original Message -----
From: "Bob McGraw - K4TAX" <RMcGraw@Blomand.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Monday, January 26, 2009 10:26 PM
Subject: Re: [TenTec] Omni VI Mod 3 and RTTY
In my opinion {there's a dangerous word} FSK is for the die hard purist.
AFSK is much easier, specially with today's radios, computers, software and
interface boxes.
73
Bob, K4TAX
----- Original Message -----
From: "Tim Randa" <tranda@cox.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Monday, January 26, 2009 9:20 PM
Subject: Re: [TenTec] Omni VI Mod 3 and RTTY
A quick question on the subject. Why bother with the FSK when AFSK gets
the job done with much less hassle. Is there an advantage to FSK that I
as a extremely casual RTTY user haven't a clue about?
de Tim KØFL
Bob McGraw - K4TAX wrote:
> I too used my Omni VI Plus on FSK. The 250 Hz filter worked will with the
> PBT properly adjusted. The manual covers the alignment of the PBT
> circuit.
>
> One extremely important point in using FSK is that the BFO oscillators
> need
> to be very precisely aligned. Follow the steps in the manual in their
> exact
> order. You probably will find it necessary to do this 2 or 3 times as
> there
> is some interaction with the adjustments. Also, a frequency counter that
> can read something in the order of 9 MHz to a resolution of 0.1 Hz is of
> great help and almost a necessity. For better results, be sure the radio
> is
> operating at room temperature for at least 1/2 hr with the covers in place
> before making these adjustments.
>
> After doing all of this, I too found AFSK was much easier to use. Took
> the
> audio IN and OUT from the connectors on the back panel and I let the VOX
> handle the RX/TX switching.
>
> 73
> Bob, K4TAX
>
>
> ----- Original Message -----
> From: "Ed" <w3nr@comcast.net>
> To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
> Sent: Monday, January 26, 2009 3:15 PM
> Subject: Re: [TenTec] Omni VI Mod 3 and RTTY
>
>
>
>> Jerry Pyle wrote:
>>
>>> I am in the process of setting up my station to run RTTY, preferably
>>> FSK.
>>>
>>> My Omni VI Mod3 has all of the filter slots filled and upon inspection I
>>> found that there is not a 217 filter amongst the bunch.
>>>
>>> I have been on the searchable archives looking for a possible Inrad
>>> filter
>>> that will work in place of the 217 (which we all know TenTec no longer
>>> makes) or another workable solution using my existing 500hz filters.
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> Jerry - WB7S
>>>
>>> Basin, WY
>>>
>>>
>>>
>>> http://wb7s.home.bresnan.net
>>>
>>>
>>>
>>> 73
>>>
>> I use my Omni6 on RTTY without a problem. Had a 217 and sold it, too
>> narrow. Use LSB and your 500hz filter(s) and you won't have a problem.
>>
>> FSK is fine as long as the 2 xtals are 170Hz apart, any more/less you
>> will not be happy. I use AFSK and as long as it is set right you won't
>> have any problems.
>>
>> If you do use FSK, the PBT needs to be set at 3 o'clock.
>>
>> All that is needed for the FSK keying cicuit is a 1K resistor in series
>> with the TXD line.
>>
>> Ed W3NR
>> _______________________________________________
>> TenTec mailing list
>> TenTec@contesting.com
>> http://lists.contesting.com/mailman/listinfo/tentec
>>
>>
>
>
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>
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