[AMRadio] WTB SB-220


peter A Markavage manualman at juno.com
Tue Sep 28 13:01:34 EDT 2004


I call it receiver capture. There is a certain level of power required by
the transmitter for the receiver at the other end to capture the signal
carrier through the noise and QRM. Once the receiver captures the signal,
barring strong fading, local interference, sun activity, etc., any
increase in power would be insignificant to the receiver. Most of the
current solid state transceivers run about 25 to 40 watts on AM
(depending on the model) and use low-level modulation. There isn't a lot
of zing to the audio when the receiver at the other end is receiving it
at QRM threshold. Adding a linear to these rigs and/or better antenna
helps the receiver capture.

If you're a builder, build a bigger transmitter. If you have neither the
time or ambition to build, a linear is an easy way to get a better signal
presence. Of course, a crappy antenna is still a crappy antenna whether
you run low or high power.

Pete, wa2cwa

On Tue, 28 Sep 2004 08:14:24 -0400 Brett gazdzinski
<Brett.gazdzinski at mci.com> writes:
> I know about the DB thing, but people running a bit of power always
> seem much stronger than the guys running 25 or 50 watts.
> 
> I cant say why, but in a qso with a bunch of people, the guys
> running 200 to 300 watts are always much stronger on the meter, and
> sounding,
> than the 50 watt guys.
> 
> For some reason, the biggest jump seems to be between about 25 
> watts
> and 100 watts.
> I don't think you HEAR as much change between say 300 and 500 
> watts,
> or even 300 and 600 watts, but go between 25 and 100 watts and it 
> seems very
> noticeable at the other end.
> 
> Maybe the losses in the antenna circuit are a much bigger 
> percentage
> of the power out when running 25 or 50 watts?
>  
> You can see the difference in signal strength when someone turns up 
> the
> power,
> and it seems to track with the DB rule, but there still seems to be
> some threshold effect in most cases.
> With 25 watts, its hard to get clearly above the noise floor in 
> many
> cases, while 100 watts and up does it easy in clear band 
> conditions.
> 
> Most times, on clear conditions on 40 meters, the guy running the
> rice box at 25 watts is just above the noise floor at about 1 s 
> unit.
> He may run between s1 and s3.
> The guy running 100 watts will run s6 to s9 or higher, and be
> arm chair copy. That FIRST 3 to 6 db boost seems to be the most 
> critical. 
> 
> And I have NEVER heard someone running 25 watts and a REALLY good 
> antenna
> out strapping a 500 watt rig into a regular antenna.
> 
> 
> And, although its easy to run an amp and boost power a little, it
> seems crazy to run a pair of heavy tubes and get 300 watts out,
> when a pair of 813 tubes plate modulated will do 700 watts
> of carrier easy, and well over 2000 watts pep!
> 
> A pair of 812a's will give 300 watts carrier without trouble!
> 
> 
> Brett
> N2DTS
>   
> 
> 
> 
> -----Original Message-----
> From: amradio-bounces at mailman.qth.net
> [mailto:amradio-bounces at mailman.qth.net] On Behalf Of RJ Mattson
> Sent: Monday, September 27, 2004 7:07 PM
> To: Discussion of AM Radio
> Subject: Re: [AMRadio] WTB SB-220
> 
> 
> Again, It would be an S1 signal above a s9/30db level noise -  a 
> barely
> perceivable difference. You would have to go from 100 to ~ 6,400 
> watts to
> get an S3 signal above that noise level.  bob...w2ami
> www.qrz.com/callsign/w2ami
> 
> 
> ----- Original Message ----- 
> From: "George Pritchard" <gpritchard at comtechpst.com>
> To: "'Discussion of AM Radio'" <amradio at mailman.qth.net>
> Sent: Monday, September 27, 2004 9:38 AM
> Subject: RE: [AMRadio] WTB SB-220
> 
> 
> > When the interference is also at 30 over S9(even if it's static 
> > crashes) a 36 dB over signal using the 400 watts helps. First put 
> up 
> > the best ant... Then crank-it with juice!!! George AB2KC
> > 1KW 4X1 lives
> >
> > -----Original Message-----
> > From: amradio-bounces at mailman.qth.net 
> > [mailto:amradio-bounces at mailman.qth.net] On Behalf Of RJ Mattson
> > Sent: Monday, September 27, 2004 9:27 AM
> > To: Discussion of AM Radio
> > Subject: Re: [AMRadio] WTB SB-220
> >
> >
> > No matter what the spin, 100 to 400 watts is only 1 s-unit and 
> barely 
> > perceptible at the receiver. A 30db/s9 signal is from a good 
> antenna 
> > not from 100 or 400 watts.
> > bob...w2ami
> > www.qrz.com/callsign/w2ami
> >
> >
> > ----- Original Message -----
> > From: "Jim Candela" <jcandela at prodigy.net>
> > To: <amradio at mailman.qth.net>
> > Sent: Sunday, September 26, 2004 10:47 PM
> > Subject: Re: [AMRadio] WTB SB-220
> > >
> > > Hmmm, the boys on 3878 are running 1500 watts pep plus
> > > on USB, and there is a 100 watt AM'er calling CQ on
> > > 3880. How much of an antenna would the AM'er need to overcome 
> the 
> > > S/N ratio? I think Astabula Bill, W8VYZ says it all:
> > >
> > > http://www.amwindow.org/audio/mov/w8vyz.mov
> > >
> > > Ever hear Bill running 100 watts? When Bill and Less
> > > K6HQI (sk) were regulars on 14286 they had to run
> > > heavy iron to hold the frequency. A 100 watt rig was
> > > seldom heard whereas a 500 watt rig (that 6db again)
> > > was often armchair copy, and sometimes often drive the
> > > QRM away.
> > >
> > > Regards,
> > > Jim
> > >
> > > RJ Mattson <rjmattson at hvi.net> wrote:
> > > If you can't get out consistantly with a Viking II,
> > > you need an antenna -
> > > not an amp.
> > > bob...w2ami
> > > www.qrz.com/callsign/w2ami

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