I think based on the work by SM5BSZ i think a good standard to aim for
in ham transmitters would be the FCC's Part 80 maritime IMD mask
standard. It requires 3rd order products to be down 30 db as referenced
to 1 of 2 tones. The standard addresses the specific issue of wide
band splatter in that the standard requires higher order IMD products
of the 11th order to be down 75 db. This is even more stringent than
what SM5BSZ wishes for. I think from memory it was something like 80 db
down at 20khz that he was calling a "clean" transmitter, i cant recall
what reference he was using whether it was PEP or below one of 2 tones.
Craig
VK3HE
sm0aom@telia.com wrote:
> Most interesting discussion.
>
> Peter wrote: "On the other hand, if in a 10kHz wide band starting 6.75
> kHz away, you aren't down 50dB, then you're somewhat antisocial
> anyway."
>
> It appears, from i.a. SM5BSZ's measurements, that "antisocial
> behaviour" would be quite common
> in current amateur radio transmitters.
>
> Not having the text of ITU-R SM329 immediately available, I am
> somewhat uncertain of the meaning of the required suppression, it may
> be referring the total mean sideband power in the 10 kHz band, or it
> may be referring to a normalized sideband power compared to a
> normalized power within the "necessary bandwidth".
>
> In either case I am quite convinced that very few amateur transceivers
> meet the SM329 requirements "barefoot", especially when using liberal
> amounts of ALC. The situation when
> using an "amp" usually will not be better.
>
> On another note, I find it most gratifying that the UK authorities
> still refer to the ITU-RR in their regulations.
>
> In Sweden, deregulation (as previously referred to) has progressed to
> a point where the ITU-RR has no legal force any longer. The content of
> the current amateur radio rules are not specifically derived from the
> RR, as they previously were, but instead they are worded in a very
> cautious and vague way not to infer any connection with the RR. As I
> have understood the "legalese" from the PTS (Swedish Post and
> Telecommunications Authority), any incorporation by reference of the
> ITU rules would not be permissible by adminstrative law, and be turned
> down by an administrative court in case of dispute.
>
> Another complication is that the amateur radio service in Sweden has
> become "license exempt",
> which means that the legal protection (and responsiblities) that a
> licensing arrangement used to provide are no more. This was "marketed"
> as the suspension of the "licensing fee", which was applauded by the
> SSA (the Swedish national amateur radio society) officials as a means
> of attracting more new amateurs.
>
> Little did they understand the long-term implications of this "offer".
>
> "Brave New World..."
>
>
> 73/
>
> Karl-Arne
> SM0AOM
>
>
>
>
>
>
>
>
> ----Ursprungligt meddelande----
> Från: g3rzp@g3rzp.wanadoo.co.uk
> Datum: Jul 3, 2006 10:06:29 AM
> Till: "W.F van Wyk" <zs6arf@telkomsa.net>, g3rzp@g3rzp.wanadoo.co.uk
> Kopia: amps@contesting.com
> Ärende: Re: [Amps] Maximum RF output in practical application: 4-250A
>
> Wynand - and this applies generally, I think -
>
>
>> WE are already in ZS in a grey area of owning equipment capable of
>>
> more than 400W so the last think we need is the regulator having to
> enforce
> the regulations<
> We need to bear in mind the spurious emission requirements enshrined
> in Radio Regulations by ITU-R Rec. SM329. Interestingly, the FCC
> managed in their last update of Part 97 to implement the requirements
> incorrectly - they have it as requiring harmonics and spurious as -43
> dB, when it should be -43 plus 10log P, where P is the PEP, and for HF,
> not needing to exceed 50dB. Even then, they didn't make as much of a
> mess of things as the UK! The requirements for commercial equipment in
> the EU are less than the Radio Regs, but the UK licence says we have to
> abide by the RR! So you can legally buy a piece of kit that in theory
> you can't use. Fortunately, the enforcement in the UK is so minimal it
> doesn't have any effect........
> However, we should aim for all harmonics to be at least 50dB down -
> not exactly too difficult - but high order IMPs might be. To meet the
> RR, emissions separated by 250% or more of the necessary bandwidth (say
> 2.5 times 2.7kHz) should be down 43+10log P, not exceeding 50dB for an
> HF tx. Nobody is sure whether the number for harmonics above 30MHz from
> a tx operating below 30MHz need to meet the 43+10logP not exceeding
> 70dB that applies to transmitters above 30MHz, or 43+10logP not
> exceeding 50dB. That applied to the Chairman of ITU Task Group TG1/5
> where some of these numbers came from, too! On the other hand, if in a
> 10kHz wide band starting 6.75kHz away, you aren't down 50dB, then
> you're somewhat antisocial anyway.
> Personally, I think that SM329 isn't very good: unfortunately, I
> wasn't at ITU-R TG1/3 where a lot of this started. Incidentally, that
> edition of SM329 was the first time there had ever been any limits on
> amateur transmitters, and because nobody thought about the effects of
> phase noise on narrow band transmitters, the limits at microwaves are
> ridiculous. This has been changed somewhat after the satellite people
> realised their tracking beacons are narrowband and thus have the same
> phase noise problems as amateurs! Ironically, the whole thing on
> spurious came about because of radio astronomy complaining about the
> spurious emissions from Iridium satellites in radio astronomy bands,
> and like Topsy, it 'just growed'. But an Administration enforcing the
> rules and complaining to other Administrations about their amateurs
> could cause us problems if we don't at least meet the RR spurious
> emission limits. The use of HF isn't going away, and there are a lot of
> people would like our ban
> ds....
> Hopefully this isn't considered too far off the amps topic....
> 73
> Peter, this week SM5/G3RZP
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