[Elecraft] K2: KPA100 Removal

[Richard Ferch]

A couple of other points to consider:

1. I find that my K3's finals get hotter in PSK31 at 50% power than they 
do in RTTY at 100% power, but that's very likely due to the fact that my 
RTTY QSOs are in contests, with very short transmissions, whereas my 
ragchew-style transmissions in PSK31 last a lot longer before giving the 
finals a break to cool off between transmissions. Of course, the breaks 
also last longer during ragchews, but the peak temperatures will still 
be higher with longer transmissions. Depending on your operating and 
conversational style, this may be a factor.

2. PSK31 is very intolerant to non-linearity. The "crest factor" of 
PSK31 can be up to 2, i.e. the peak power can be twice the average 
power. Since it is clipping of the peaks that causes splatter, with most 
radios you need to keep the output power below one-half the rated 
maximum in order to ensure linearity. Linearity is not a problem in 
RTTY, but it matters in PSK31.

73,
Rich VE3KI


Don W3FPR wrote:

> Your 1/3 rule is right for continuous duty data modes like RTTY, but I
> understand (and have not tried to figure out the details for myself)
> that plain PSK31 does not come up to a full duty cycle - something about
> the coding, so you might go up to 1/2 the normal rated power - 6 or 7 watts.
>
> If you push it more than that, put your hand on the bottom rear cover
> once in a while.  If it is too hot to hold your finger on it constantly,
> then you should back off the power a bit.
>