[UK-CONTEST] AFSK RTTY operation

[G3VDB (Jim)]

> be certain the speech processor is OFF
> when using .......

.... using ANY mode that injects audio into the mic or data audio sockets
and expects to achieve a linear translation to RF - ie most data modes. It
is easy to leave processing on after a major SSB stint and then go to data
without thinking.  

Also, make sure that the audio level is reduced until there is no ALC
movement and then reduce it a bit more. If possible set the transceiver
power output to maximum and then reduce the audio level to achieve the
required (and lower) power output preferably no more than half power to my
mind. Multi-tone modes have a higher peak to mean power ratio than rtty or
PSK and need headroom.

If you have a five or ten max watt rig, you need to be particularly careful
about running it at that limit to try to get the maximum power from your rig
- you may be more readible with 3dB less mean power and an improved signal
quality. 

With one or two exceptions presumably from relative new comers to the mode,
the (psk) signal quality was good last night. 

[I am in the habit of taking waterfall screen shots and short audio
recordings of transmissions that are spreading; I send the results in an
email where available. Usually this is welcomed! And, when my sig is not
meeting these standards, I expect to be told, please!]

Jim
G3VDB 


-----Original Message-----
From: uk-contest-bounces at contesting.com
[mailto:uk-contest-bounces at contesting.com] On Behalf Of Dez Watson
Sent: 12 February 2009 15:39
To: UK Contest Reflector
Subject: Re: [UK-CONTEST] RTTY operation (was ARRL Contests)


For many years I used a FT-1000MP MK-V for FSK RTTY.

The traditional advantages of FSK over AFSK were the ability to use 
narrower filters (250 Hz is about the minimum)
and direct keying of the transceiver so there's less chance of 
over-modulation of the tones.

I did an awful lot of RTTY running from ZC4 land and the best solution 
for me was to use the transceiver
RIT for the small minority of callers who called slightly off frequency.

For Search & Pounce I used a really slow VFO dial speed to aid accurate 
tuning.

More recently I run a AFSK with a IC-7000

DSP filters these days mean you can often tailor the passband of the RX 
filters to be almost as good as
the narrow RTTY filters in FSK-enabled rigs.

It's much more easy to generate poor audio tones using AFSK so be 
certain the speech processor is OFF
when using AFSK RTTY, or PSK for that matter.

I still prefer to use transceiver RIT when running for the few who do 
call off frequency - but most ops seem to be able
to tune in a RTTY signal without too much bother.

I never use NET or AFC as these are a recipe for wandering all over the 
band and best left unticked.

73

Dez G3WW (ZC4DW)
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