[RTTY] INRAD filter question

[Tom Osborne]

Hi David

Go to www.k4abt.com.  He makes a RASCAL that works great for FSK RTTY with 
the TS-450.  I have 2 of them here, plus one for AFSK with my FT-840 when I 
use it.

They are pretty cheap and they work very well.  73
Tom W7WHY


>
> So its all good news.  Adjusting the IF shift brought the RTTY signal into 
> the passband of the 400hz filter using AFSK in LSB.  Notwithstanding the 
> technical reasons this worked,  it was a beautiful thing to see for 
> someone who had been doing casual RTTY for a year using SSB width filters. 
> Conditions on 15 & 20m were pretty nice this afternoon and trolling 
> through the RTTY band segment working one station after 
> another...........sweet.  I'm ecstatic.  The 450 is now the dedicated 
> digital rig.
>
>
>
> I do think that getting my setup to transmit FSK would have some 
> benefit........but Joe,  I'm the guy you want sewing your face back on 
> when you flip your sled over somewhere north of 60.  If you have to wait 
> for me to find a pair of NPN transistors first, well, it might not go so 
> well.............hihihi  :)   Seriously...............do you know of a 
> commercial product.  Dont forget, it took me 7+ months to get the INRAD 
> filters working   :)
>
> David
>
>
>
>
>
>
>> Date: Sun, 26 Sep 2010 18:07:33 -0400
>> From: lists at subich.com
>> To: rtty at contesting.com
>> Subject: Re: [RTTY] INRAD filter question
>>
>>
>> > The TS-450 has a +/-2.2Khz IF shift. This may not be quite enough to
>> > get the RTTY signal inside the passband. The 450 also has a menu
>> > option to change the receiver tone from 2125 to 1275hz. This may be
>> > irrelevant though as it is for FSK mode.
>>
>> If the narrow filter is centered at 600 Hz in LSB, a 2.2 KHz offset
>> should get you to 2800 Hz which should be more than enough. Check
>> it though.
>>
>> > PLAN-B if this fails, is there a simple& inexpensive interface
>> > that I can use to do true FSK. USB to 13pin DIN...........??
>>
>> See the information on AA5AU's web page:
>> http://www.aa5au.com/rtty.html.
>> You will need a pair of NPN transistors driven from the RTS/DTR
>> lines of a typical USB to serial converter with EXTFSK to generate
>> the FSK/PTT signal. You can continue to use the Signalink USB for
>> PSK31/other digital modes and for receiving RTTY.
>>
>> 73,
>>
>> ... Joe, W4TV
>>
>> On 9/26/2010 11:11 AM, David VE3VID wrote:
>> >
>> > Confusion is clearing a bit, check my thinking on
>> > this.................. The 400hz filters are listening over a
>> > portion of the band away from the section where the mark and space
>> > tones will be heard. So the reason it sounds so beautifully quiet is
>> > because I'm listening to the null outside the filters bandpass.
>> > Yes?
>> >
>> > The TS-450 has a +/-2.2Khz IF shift. This may not be quite enough to
>> > get the RTTY signal inside the passband. The 450 also has a menu
>> > option to change the receiver tone from 2125 to 1275hz. This may be
>> > irrelevant though as it is for FSK mode.
>> >
>> >
>> >
>> > I'll be back in the op chair this afternoon and give these options a
>> > try then get back to the email thread. PLAN-B if this fails, is
>> > there a simple& inexpensive interface that I can use to do true FSK.
>> > USB to 13pin DIN...........??
>> >
>> >
>> >
>> > David
>> >
>> >
>>
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