[UK-CONTEST] Quest for QRO

[Ian White GM3SEK]

Paul O'Kane wrote:
>----- Original Message -----
>From: "Ian White GM3SEK" <gm3sek at ifwtech.co.uk>
>
>> 100W of carrier with 100% high-level AM equates exactly to 400W PEP.
>> The person to thank for getting that right - and making sure RSGB
>> and the licensing authority got it right too - was G2DAF.
>
>I'm impresssed, but that is far from the full story.
>
>What I would like to know is why, exactly, did the permitted
>power on CW change overnight from 100w PEP (nominally equivalent
>to 150w DC input on CW) to 400w PEP?
>
>After all, it was not considered to be a general increase in
>power.  Therefore, it must be related to the change in definition
>of power.  Therefore, someone was conned, and it wasn't the
>amateurs

It all made complete sense in the early days of SSB because people would 
typically be using completely different transmitters.

The old AM/CW transmitter would have been designed for 150W DC input, 
typically to a pair of 807s or a single 813 in class C. This produced 
about 100W carrier output, and needed an equally large push-pull 
modulator to reach 400W PEP on AM. The other transmitter was the new SSB 
exciter (probably home built) which needed a much larger linear 
amplifier to reach 400W PEP output.

So although we had a two-level power limit of 100W output (effectively) 
on CW and 400W PEP output on both AM and SSB, there wasn't any sense of 
"turning down the power" in those early days. That is a much more modern 
perception, because...

What nobody anticipated was the rise of the all-mode transceiver. With 
its all-mode exciter and exclusively linear PA, such a transmitter 
generates essentially the *same* PEP output on all modes. That was when 
the two-level power limit stopped making sense.

Most amateurs started out with a barefoot "100W" transceiver, where it 
was perfectly legal to flick the mode switch from SSB to CW and continue 
at the same PEP. When they added a 400W linear amplifier, large numbers 
of amateurs (to my certain knowledge) continued to do exactly the same. 
It wasn't that they were deliberately breaking the licence conditions, 
they didn't even realise there *was* an issue.

It's hard to blame anyone for that, because the regulations didn't make 
any technical sense, except for historical reasons.

This situation persisted for many years, with both the licensing 
authorities and RSGB studiously ignoring this widespread lack of 
compliance, like ignoring the proverbial "elephant in the room". When 
all modes were eventually rounded up to 400W PEP output in the licence, 
nothing happened in the real world because it only legitimised what most 
people had already been doing.

And without a single word being said, everyone agreed that the elephant 
had gone away.

> we were laughing all the way to our linear amps  :-)
>

Please, no!  We still don't talk about the *other* elephant.




-- 

73 from Ian GM3SEK