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Re: About (HAMSAT) VO-52 Beacon



William
     Great job on building the transponder yourself. Surprised to hear you
received no funding support with the talent you obviously you have. As in
"Top Gun", call me I'll fly with you next time for some support.

73 Bruce KG4YEV

----- Original Message ----- 
From: "William Leijenaar" <pe1rah@YAHOO.COM>
To: <amsat-bb@amsat.org>
Sent: Friday, November 25, 2005 10:04 PM
Subject: [amsat-bb] About (HAMSAT) VO-52 Beacon


> Dear AMSATs,
>
> I wish I had the same free time now as when I designed
> the HAMSAT and P3e transponder. Unfortunatly these
> times have been changed (for the moment) due to QRL
> things.
>
> However, I often try to be QRV on the HAMSAT and check
> the signals from my transponder and read the messages
> on amsat-bb. I just read about the beacon "problem".
> The "problem" with the beacon is actually not a
> problem but it is known. The beacon signal is injected
> at the IF, and runs throught the transponder from the
> IF section, up converter, via the final PA to the
> antenna.
>
> The changes you hear on the beacon frequency is caused
> by the amplitude limiters in the IF that are activated
> by a too strong uplink signal. These limiters are only
> for protection, to avoid that the IF and VHF
> amplifiers get overloaded and generate all kinds of
> unwanted signals at the output.
>
> My transponder is straight forward to keep it physical
> small and cheap in cost (as I had no sponsors). Unlike
> most other transponders my transponder on HAMSAT has
> no AGC system. It gives always maximum gain with
> maximum sensitivity. The main reason is that the AGC
> systems I had didn't fit in the small sized box. As an
> option I choose for limiters, and it worked great in
> tests.
>
> Secondly, I tought limiters might be helpfull against
> aligators. To deal with too strong signals most
> transponder have an AGC to lower the RX gain, and
> actually be helpfull to the alligators.
> With the limiters their SSB signal will get distorted
> and they might lower their powers to have better audio
> quality.
>
> The change in beacon sound is an indication for too
> much uplink powers and will be heared mainly in areas
> where higher powers are available on the uplink, like
> US, Europe, Japan...
>
> Its funny to know that nobody here has discovered that
> the bandpass is shifted some down in frequency...
> There is no technical failure, the reason is known
> here...
> No panic please :o)
>
> Please keep in mind that this transponder is my privat
> work and privat money. Frankly speaking this is my
> privat transponder I "give" to the amateur world. I
> was one of those many poor students, and this was the
> best I could do with my resources I had available at
> that time... The whole thing is just 16cm x 10cm x 3cm
> !! even smaller than the professional Indian
> transponder :o)
>
> I hope you all enjoy my transponder even when it is
> not perfect,
>
> 73 de PE1RAH
> William Leijenaar
> ---
> Access over 1 million songs. Try it free.
> http://music.yahoo.com/unlimited/
> ----
> Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
> Not an AMSAT member? Join now to support the amateur satellite program!
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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