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Re: S-band receiving requirements



I don't think so!!! I work with 2.4 Ghz every day at the company I work for and
we use times microwave and I have talked to their engineers many times and they
have told us that this is what we should expect... So believe what you would
like but this is still my answer to the question.

        Guy Lemke
        KD6MTU

Pieter Ibelings wrote:

> 0.5 dB per N connector? Sounds like too much! I have measured a pair of BNcs
> and a pair of N connectors all in a line at 1.5 GHz and I get less than 0.5
> dB. I doubt that a single one is 0.5 dB. Maybe if you buy the radioshack
> versions.
>
> Pieter
>
> ----- Original Message -----
> From: "guy lemke" <guy@com-pair.net>
> To: "Jerry Pixton" <jpixton@shentel.net>; <amsat-bb@AMSAT.Org>
> Sent: Sunday, May 20, 2001 13:48
> Subject: Re: [amsat-bb] S-band receiving requirements
>
> > You should figure in .5 Db per N connector if they are of good quality !!!
> >
> > Jerry Pixton wrote:
> >
> > > Mike and Gene,
> > >
> > > Ya, that coax ahead of the preamp/downconverer is all important. What is
> > > the loss at 2400 Mhz of just a male/male N connector between the antenna
> > > and converter  I have been using 0.25 db as a wag.
> > >
> > > If I have a helix antenna with 17 dBic, does that mean I should enter 14
> > > into the spread sheet to cover the loss from circular to linear. Or
> should
> > > I be entering 20 since my antenna is really 3 db better than a linearly
> > > polarized antenna?????  The antenna gain seems to be used on the data
> sheet
> > > to compute the transponder levels. Is the 3 db polarity loss embedded in
> > > the "24" factor at the end of the equation?
> > >
> > > Jerry W6IHG
> > >
> > > At 08:17 AM 5/19/01 -0400, Mike73@aol.com wrote:
> > > >In a message dated 5/18/01 8:40:08 PM Eastern Daylight Time,
> > > >al7eb@ptialaska.net writes:
> > > >
> > > > >  Gene Marcus' spreadsheet is very useful for this process.
> > > >
> > > >I agree!!  A couple of pointers.....
> > > >
> > > >The very first coax loss number before the preamp is very important.
> This
> > > >really effects overall system noise. I calculated the 3 foot jumper
> (RG-8) on
> > > >my Meyers dish as -.36 dB at 2400 (yuk). Throw that number in the
> spreadsheet
> > > >and see what happens.
> > > >
> > > >Also, I asked Gene about the antenna gain. The number you input is dBi
> > > >Linear. So to be accurate, if you're using a Meyers dish you should
> subtract
> > > >3 dB for the theoretical loss when going from linear to circular. So,
> for a
> > > >Meyers dish that was advertised as 25 dBi, you would input 22 dBi.
> > > >
> > > >I can see if I were to do any improvements to my system, I'd probably
> attack
> > > >the antenna. I already have a good low NF preamp. The changes I'd
> contemplate
> > > >would be to change the feed to circular and reduce the coax loss before
> the
> > > >preamp. To see the effect of these two changes, input .1 dB for first
> coax
> > > >loss and 25 dBi antenna gain in the spreadsheet and you'll see the
> > > >improvement.
> > > >
> > > >Now back to cobbling together a 5668 uplink :-}
> > > >
> > > >73,
> > > >Mike, N1JEZ
> > > >AMSAT #29649
> > > >Local Area Coordinator
> > > >"A closed mouth gathers no feet."
> > > >----
> > > >Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> > > >To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
> > >
> > > ------------------------------------------
> > > Dr. Jerry R. Pixton, PIXOS Designs LLC
> > > http://www.pixos.com/designs/
> > > jpixton@shentel.net
> > > ------------------------------------------
> > >
> > > ----
> > > Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> > > To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
> >
> > ----
> > Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> > To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
> >

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