[amsat-bb] Re: Alone on L/S ON A0-51

Sat Sep 13 18:38:44 PDT 2008

Greg,

There is a way to figure out how much power you are getting to your 
mode-L antenna.  Times MIcrowave has a on-line calculator for many of 
the more popular cables.
http://www.timesmicrowave.com/cgi-bin/calculate.pl

If you use the numbers for LMR-600 (3.056-dB/100-feet) in place of 
your 1/2-inch hardline you get:
60-feet of cable: Loss=1.8 dB   Efficiency = .656

For RG-214 (8.472-dB/100 feet):
10-feet of cable: Loss=0.8 dB  Efficiency = .823

add the loss in dB = 2.6 dB, or multiply the efficiencies = 0.54
So 10w x 0.54 = 5.4w
This is a lot for AO-51.

Ain't math fun ;-)
73 Ed - KL7UW

   At 02:22 PM 9/13/2008, Greg D. wrote:

>Hi Robert,
>
>The equipment is my receive side from my AO-40 setup, along with a 
>newly acquired transmit side.
>
>The receive side starts with a home made 3 3/4 turn helix in the 
>bottom inch of a grapefruit juice can, which makes up the feed for a 
>BBQ grill antenna that I lined with window screen in order to make 
>it usable for circularly polarization.  There's a Khune 2.4 ghz 
>preamp (highly recommended!) attached to the feed, and a short cable 
>to one of those infamous Drake downconverters.  I modified the Drake 
>in an unusual way, moving the local oscillator from whatever it was 
>to 2100 mHz.  That put AO-40's 2401.3xx mHz downlink in the middle 
>of the Drake's design passband, and in a nice place between our 2m 
>and 70cm bands so that I could use either as an uplink without 
>interference.  There's about 60' of Quad-shield RG-6 out the back of 
>the Drake to the shack. where it terminates on a power injector 
>connected to a multi-way Radio Shack RF (video) switch.  The switch 
>allows me to select our pre-Cable TV antenna (never throw anything 
>away!) or the Drake as an input to an old ICOM R-7000!
>   all-mode scanning receiver.  The receiver is pretty deaf by many 
> standards, and AO-40 was never more than an S1 or S2 on the meter, 
> but it worked.  (I've had AO-51 up to about S4 recently.  Wow!)
>
>The transmit side starts in the shack with an ICOM 1271A tranceiver 
>that I picked up from a fellow Ham last year.  I'd never been on 1.2 
>gHz before, so this was new territory.  The tranceiver feeds a few 
>feet of RG-8-like stuff (RG-214, I think) to get out of the shack, 
>then there's about 60' of 1/2" hardline up to the roof, where it 
>switches again to the RG-8-like stuff to go around the rotor and up 
>to the antenna.  The antenna is an 18 turn helix that I made from 
>aluminum ground wire and wire ties.  About 10 watts goes into the 
>coax in the shack; not sure what makes it out the other end, but 
>it's apparently quite sufficient for AO-51.  I didn't have the 1.2 
>gHz equipment when AO-40 was working, so I don't know how well it 
>would have worked on the higher altitude satellites.
>
>The rotor assembly is home made; ham and tv-type rotors, run from a 
>homebrew controller.
>
>Pictures at http://home.wavecable.com/~ko6th, at the bottom of the page.
>
>So, to answer your question, a lot of my getting on the microwave 
>bands has been through stuff that I have built myself, with a few 
>key components acquired opportunistically as they came around.  From 
>what I've seen recently, there are still downconverters to be had, 
>as are the grill dishes, etc.  Lots of folks have used the small 18" 
>satellite TV dishes that many neighbors are giving away for 
>free.  The key is to be constantly hunting for stuff, designing and 
>re-designing as you go, depending on what you can come up with.
>
>Hope this helps.  Good luck!
>
>Greg  KO6TH
>
>
>----------------------------------------
> > CC: amsat-bb at amsat.org
> > From: xunil at xunil.net
> > To: ko6th_greg at hotmail.com
> > Subject: Re: [amsat-bb] Re: Alone on L/S ON A0-51
> > Date: Sat, 13 Sep 2008 11:40:47 -0700
> >
> > Hi Greg-
> >
> > Too bad about the lonely pass.  I haven't done a lot of research since
> > I (recently) got back into working the birds, but from what I remember
> > in the AO-40 days, my biggest problem working the microwave modes was
> > finding equipment.  I remember Down East made microwave gear but they
> > were moving offices for what seemed like forever, and now it appears
> > they're swamped with backlog and aren't able to fill new orders.
> >
> > My question is, what L/S gear do you use, and where does one find
> > microwave gear these days?
> >
> > 73, Robert KC0KNM
> >
> > On Sep 12, 2008, at 8:45 PM, Greg D. wrote:
> >
> >>
> >> Hi Luc,
> >>
> >> Well, I guess the other parts of this planet are a bit more active
> >> than out here on the coast...  Really nice 50+ degree pass this
> >> evening, and again I was all alone on LS.
> >>
> >> Greg  KO6TH
> >>
> >>
> >> ----------------------------------------
> >>> From: lucleblanc6 at videotron.ca
> >>> To: amsat-bb at amsat.org
> >>> Date: Fri, 12 Sep 2008 10:04:42 -0400
> >>> CC: eu-amsat at yahoogroups.com
> >>> Subject: [amsat-bb] Re: Alone on L/S ON A0-51
> >>>
> >>> On 11 Sep 2008 at 22:59, Greg D. wrote:
> >>>
> >>>>
> >>>> {snip}
> >>>>
> >>>>>
> >>>>> P.S.  Remember, AO-51 is in mode J-FM on the 'QRP' side
> >>>>> (435.15/145.88)
> >>>>> this week.
> >>>>
> >>>> Also remember the main side is in LS.  I had the whole bird to
> >>>> myself again tonight...
> >>>>
> >>>> Greg  KO6TH
> >>>
> >>> Not quite VE3NPC,KD8CAO,WB8OTH,KC9ELU, and myself are there too
> >>> when they are able to find the right uplink on L... But if i can
> >>> succeed to
> >>> have the uplink controlled by a PC L/S will be a greath mode +-
> >>> path obstruction (Just hope they will put the sat in this mode
> >>> again this
> >>> winter)
> >>>
> >>> BTW I don't know the extent of L/S mode operation in europe and in
> >>> the rest of the world?
> >>>
> >>>
> >>> "-"
> >>>
> >>>
> >>> Luc Leblanc VE2DWE
> >>> Skype VE2DWE
> >>> www.qsl.net/ve2dwe
> >>> WAC BASIC CW PHONE SATELLITE
> >>>
> >>>
> >>>
> >>> _______________________________________________
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> >>
> >> _________________________________________________________________
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