[Elecraft] RTTY FL Settings

[Bill Coleman]

On Dec 20, 2006, at 12:08 PM, Bernard Gaffney, N8PVZ/QRP wrote:

>  I want to set up the RTTY FL filter settings for use
> with PSK31/63. As a good starting point, I assume the
> RTTY settings should be set to match the SSB settings.

You should have the at least one filter set to the OP1 filter.

> Same for the BF settings? No problems experienced
> using SSB for PSK.

There are a couple of benefits to using the RTTY filters instead of  
the SSB:

1) You can set the variable bandwidth filter centered around RTTY (or  
PSK) frequencies, settings that wouldn't make sense for copying SSB.

2) the audio compression settings are separate for RTTY and SSB. So,  
if you set the SSBC value for one mode, you can set it to 1:1 for RTTY.

> Currently, my FL settings are:
>
>       SSB    RTTY
> FL1   OP1    2.20
> FL2   OP1    2.00
> FL3   1.80   1.80
> FL4   0.75   1.60

This doesn't make much sense to me. You're using the variable- 
bandwidth filter for all three RTTY filter settings. Unfortunately,  
the VBF has a very asymmetric response at bandwidths greater than  
about 1.0 kHz.

I set up my RTTY filters as follows

FL1 OP1
FL2 1.0
FL3 0.5
FL4 0.3

All the variable bandwidth filters are centered on 1500 Hz (1415  
Mark, 1585 Space). RTTY REV is set up the same way for use with PSK.  
I try to pick PSK frequencies near 1500 Hz.

The nice thing about this set up is that the FL1 filter is set wide,  
FL2 is narrow enough to tune RTTY stations, FL3 and FL4 can be put in  
to really block out adjacent QRM.

> Also, when switching to RTTY, does that imply I'm
> using the SSBCr setting?

Yes.

> I may of course have to tweak the settings as I go
> along.

I wouldn't suggest using the VBF at bandwidths wider than about 1.2  
kHz. Once the filter stops being a single peak with smooth slopes,  
you might as well go to the OP1 filter.


Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901