[amsat-bb] Roast "ham", anyone?

["Frederick M. Spinner" <fspinner@xxxxxxxxxxx>]

Actually, this is interesting.  Lets assume you run 100 W--
+50 dBm

I'd assume that an Arrow has to have at least 25 dB F/B.  So say
you see +25 dBm pointed back at you.  Thats 316.2 mW.

I'm not saying you should do this, but I'd imagine you could get more than 
that exposure from your HT with a rubber duck.

I'm obviously ignoring "near-field" effects, multi-path, etc., but it's 
still interesting to think this one through in this simple fashion.

On the other hand, if your going for a "Darwin Award", and say the beam has 
8 dbi gain (it's probably more than that!), then you'd look into 631 W ERP, 
if you pointed it at yourself or your "friendly" neighbor.  This is of 
course what you'd present to the satellite also, with should be mimimally 
effective on the FM sats!  (tongue-in-cheek)
This might be advantageous in one of our Iowa winters, though!  Built in 
foot warmers!

I think at 10-25W you'd be safe with the arrow in hand, as long as you 
didn't point it at anyone!!!

Fred W0FMS


>From: "Margaret Leber (K3XS)" <maggie@voicenet.com>
>To: Bryant Winchell <bryantcw@home.com>
>CC: AMSAT BB <Amsat-bb@AMSAT.Org>
>Subject: Re: [amsat-bb] GRRRRRRRRRRR!
>Date: Thu, 01 Mar 2001 18:02:48 -0500
>
>Bryant Winchell wrote:
>
> > Your post re-emphasized a concern I've had with the manual use of 
>antennas
> > such as the much discussed Arrow. My concern is the power lobe at 180
> > degrees that the antenna emits [more or less directly back at the 
>operator].
> > With a handheld and a few watts power output there shouldn't be a 
>problem to
> > the operator.  But you mentioned using your FT-847......
>
>Well, the "once" in question was indeed my only attempt to use the 
>FT-847/Arrow
>combination; at the time I was still an apartment dweller, and had not had 
>the
>opportunity to actually use my "Earthstation" on a satellite. The radio was
>powered from a "jumpstart your car" powerpack. As I recall, that evening I 
>had
>not done extensive preparation of cables and was using the built-in 
>duplexer
>rated at 10w, along with another duplexer to combine the 847 outputs into a
>single feed and was more concerned with frying that than with any RF 
>exposure I
>might have been subjecting myself to with the back lobe...certainly a 
>matter for
>concern and investigation if I was loony enough to make this a regular 
>practice.
>
>As it was, it was only a temporary once-off hack-job; I do recall being 
>thrilled
>to actually hear my signal on the downlink (something you couldn't do with 
>the
>VX-5) before the wind blew my tripod over. Come to think of it, I *was* 
>using a
>tripod, and not handholding the antenna, other than armstronging it with 
>the
>tripod handle.
>
>It *was* really awkward, I certainly don't recommend it, and I'm happy to 
>run a
>fixed operation with the 847 now. Anybody who wants to use an Arrow at 
>power
>levels exceeding the 10w limit Al recommends hand-held is on their own for 
>RF
>safety, of course. He specs it at 150w for a mounted application.
>
>  73 de Maggie K3XS
>
>--
>-----/___.   _)   Margaret Stephanie Leber    / "The art of progress  /
>----/(, /|  /| http://voicenet.com/~maggie   / consists of preserving/
>---/   / | / |  _   _   _    `  _AOPA 925383/ order amid change and /
>--/ ) /  |/  |_(_(_(_/_(_/__(__(/_  FN20hd / change amid order."   /
>-/ (_/   '  K3XS  .-/ .-/    ARRL 39280   /___ --A.N.Whitehead ___/
>/____ICQ 7161096_(_/_(_/__AMSAT 32844____/ <maggie@voicenet.com>
>----
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