[FoxHunt] Attenuator

[Bob]

Here is the application note for the 8307...
http://products.analog.com/products/info.asp?product=AD8307
Bob,WB6JPI

Bob wrote:
> 
> I've been trying to get Tony to part with one, but it is si
> simple that he hasn't gotten to it. Contact Analog Devices
> and get the application note for the AD-8307 and go from
> there. I think there is a tuned circuit, a few stabilizing
> caps and a resistor or two involved and thats it for the RF
> thing. The chip inputs RF and outputs DC. The clicker is a
> 555 circuit set up for a voltage controlled VFO. The
> attenuator is just resistors. The key to getting the thing
> to work at close in is the shielding of the chip. I think
> the chip costs about $12.00. Let me know what you find.
> 
> Bob, WB6JPI
> 
> Uwe DF7BL wrote:
> >
> > Hi Bob, ist there a way to get the schematic of that sniffer. May be direkt.
> > Sorry for the list but mailman does not accept attachments.
> > 73 de uwe df7bl
> >
> > Bob schrieb:
> > >
> > > My friend Tony has built a sniffer around the Analog Devices
> > > Logrithmic amplifier chip. Here is his report...
> > >
> > >    "This week I finished my new sniffer with the AD 8307. It
> > > is
> > > the best I have ever used. I combined the 8307 and a ticker
> > > that goes up
> > > in tone with more RF. It starts to tick at -107 dbw and has
> > > 70 db dynamic range to the high tone. I then can switch in
> > > 30 and 35 db
> > > attenuators to numb it  60 db. The lost 5 db is some kind of
> > > leakage. (marginal shielding)   I think I did the
> > > measurements correctly.    I can stand in my yard and key a
> > > repeater 10 miles away and it
> > > will start to tick when pointed in that direction. With the
> > > switches in, -60db, I can DF my repeater, 80 watts at 25
> > > feet."
> > >
> > > I suggested to Tony that he replace the toggle switches with
> > > relays and use bypass feedthroughs for the wires to get
> > > better shielding. He is working on numbing down the 8307 as
> > > well. It is one hot chip It takes almost no support parts
> > > and has a 90 dB dynamic range if you can figure out how to
> > > get them all.
> > >
> > > cut cut....
> >
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