[FoxHunt] Attenuator

[Uwe DF7BL]

Hi Bob,
at that adress I found all I need. There is an applicationsheet in .pdf 20
pages, on No. 16 I found "1�W to 1 kw 50 ohm Power Meter." That is an AD8307
with a little bit more than nothing. Here in Germany the chip cost's 17 � an it
is available! A clicker like a Gaigerclicker is very easy. I build that in an
other sniffer, it is very comfort to search with that. Thank you for that hint.
73 de uwe df7bl (excuse my bad english)
Bob schrieb:
> 
> 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....