[FoxHunt] IARU Transmitter question

Tue, 13 May 2003 21:04:00 -0700

Okay, I will admit 200M is a bit far :). I'll have to check it out
further. Joe K0OV has a circuit in the November 2000 issue (?) of 73
Magazine where it looks like it does the same thing Sam is doing with
his VOX circuit.

Thanks for the antenna info! I would *really* like to get an 80M antenna
that sets up as fast as the 2M antennas. Someone had mentioned using the
telescoping fishing poles as the vertical antenna but I haven't been
able to find more information about that one.

BTW, I posted this a while ago, but for anyone going to the US ARDF
Championships in Cincinnati, a couple of us are going to the Ft Tuthill
Swapfest the weekend before, and will be driving to Cincinnati
afterwards. If anyone wants to carpool and share gas expenses, and is
relatively on the way, let me know.

Gerald Boyd wrote:
> 
> In Portland I was able to get one at about 200 meters out. While others did
> not go that far.
> I suspect that there are several factors that affect how well the leakage
> travels. Including good RX sensitivity. that's why I made sure that the OSC
> was turned off in 2001.
> 
> The antennas in Albuquerque used a 22 foot vertical wire with two 22 foot
> radials.  A loading coil matched the antenna.
> 
> Marvin looking forward to seeing you this summer.
> 
> Jerry
> ----- Original Message -----
> From: "Marvin Johnston" <[email protected]>
> To: <[email protected]>
> Sent: Tuesday, May 13, 2003 9:40 PM
> Subject: Re: [FoxHunt] IARU Transmitter question
> 
> Okay, I have a question then; how far can the local oscillator be picked
> up if it is left running? I also am using the ATX-80 80M transmitter,
> and tied the oscillator low so it is always running. On the bench, I
> could pick up the signal for a foot or so, but I haven't tested it with
> a full antenna on it. If it can only be picked up for 10 or 15 feet, I
> would think it is a "who cares" issue since the flag should be visible
> within that distance!
> 
> While we are on the question of questions :), what kind of an antenna
> was used on the 80M transmitters in both Georgia and Albuquerque? We
> have typically been throwing some 20 feet or so of wire up over a tree
> limb with a radial of about the same length laying on the ground. Has
> anyone done any work on a quicker-to-set-up type of antenna? I was
> thinking about an 80M mobile whip, but haven't done any research into
> finding out if that would work for championship events.
> 
> Marvin, KE6HTS
> 
> Gerald Boyd wrote:
> >
> > Sam has brought up a very good point.
> >
> > We are using the ATX-80 80 meter transmitters.
> > Our controllers have been modified to assert the OSC enable line before CW
> > keying starts. This prevents a high current condition that occurs if the
> PA
> > is keyed before the OSC is enabled.
> >
> > At the end of the cycle the reverse occurs, that it keying stops then the
> > OSC enable line is de asserted.
> >
> > When we had the original MFC code in our controllers we could observe a
> > large current spike at the start of the cycle. With the modified code that
> > does not occur.
> >
> > Our code is also modified to prevent the "smoke effect" when the led is
> > blinking in delayed start mode (original MFC controller).
> >
> > The controllers also have been modified to flash the MO code (with out
> > keying the TX)during delayed start to see that the transmitters are still
> in
> > sync. At the end of the cycle the led goes back to the blinking state.
> This
> > lets you know what is going on during delayed start.
> >
> > Mike K5ATM can give the details on how he modified the code.
> >
> > Jerry WB8WFK
> >
> > ----- Original Message -----
> > From: "Sam Smith" <[email protected]>
> > To: <[email protected]>
> > Sent: Tuesday, May 13, 2003 5:33 AM
> > Subject: Re: [FoxHunt] IARU Transmitter question
> >
> > Byon Garrabrant wrote:
> > > I'm making a change to PicCon's IARU mode, and have a question I need
> > > answered ASAP.
> > >
> >
> > I can't answer that question, but I do have another suggestion. Last
> > year for the US Champs I had to kludge a sort of VOX circuit for the 80
> > meter transmitters. What is needed is a seperate key line and
> > "transmitter on" line. The "transmitter on" signal would stay active for
> > the whole minute, while the key line does it's thing. This would assist
> > those of us using 80 meter crystal oscillators. If we let the oscillator
> > run all the time, you can DF to the very low level signal from close
> > range even when it's not transmitting.
> >
> > What I did last year was use an RC circuit with a few seconds of time
> > delay so that whenever the key line became active it would keep the
> > oscillator on.
> >
> > Sam N4MAP
> >
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> >
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