Hi,

I just bought a Lampkin 107C Service Monitor. It has an accessory
that I didn't get. It's the 20DB attenuator pad (part No. FAP-20).
Does someone have a schematic available so I can build one? I'd also
buy the unit itself.

Thanks,

Jim

wrote in message
...
Hi,

I just bought a Lampkin 107C Service Monitor. It has an accessory
that I didn't get. It's the 20DB attenuator pad (part No. FAP-20).
Does someone have a schematic available so I can build one? I'd also
buy the unit itself.

Thanks,

Jim

Nothing magical about it, you can find the values for a 20-dB
pi attenuator he

http://www.electronics-tutorials.com...ttenuators.htm

Use 1/4-watt carbon resistors with very short leads. Cushman also used
an external 20-dB attenuator on their CE-3 and CE-5 generators.
They protect the generator from accidental RF being applied to the
generator input. Note that the 20 dB pad also gives a divide by 10
for the voltage scales; it provides a decade step for voltage.

Pete

20 db pads are common and they are interchangeable - so long as they are
designed for 50 ohms. I have seen pads for 75, 92 and 300 ohms, but they
are not common.

The pad also makes the input impedance of the device receiving the signal
more constant, and is often recommended for that reason. As was stated, be
sure to compensate for it.

73, Colin K7FM

wrote:

I just bought a Lampkin 107C Service Monitor. It has an accessory
that I didn't get. It's the 20DB attenuator pad (part No. FAP-20).
Does someone have a schematic available so I can build one? I'd also
buy the unit itself.

Pomona Electronics will still sell attenuator pads. Or you can make
your own up; the schematic is in the ARRL Handbook.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"Scott Dorsey" wrote in message
...
wrote:

I just bought a Lampkin 107C Service Monitor. It has an accessory
that I didn't get. It's the 20DB attenuator pad (part No. FAP-20).
Does someone have a schematic available so I can build one? I'd also
buy the unit itself.

Pomona Electronics will still sell attenuator pads. Or you can make
your own up; the schematic is in the ARRL Handbook.
--scott

Also keeps low level noise, mixer products, etc. out of your lab setup.

I built a small unit 20-20-10 with slide switches based on the handbook out
of circuit board, using solder wick to seal the back cover and a short
RG400. About the size of the CE-6 pads. It is said slide switches have
less inductance than others but I don't know for sure. Color TV tuner
cleaner and lube was a great help (blue stuff) with my junkbox switches. It
has come in handy over and over in various applications.

I don't know if the pad is quite similar to that used on the CE-3 or
not, but if it is,
I have one of them, and could take it apart (again) (again) and (again) to
draw
a schematic. The CE-3's pad included a micro fuse to protect the CE-3 from
transmitter output. I've tested the fuse system a number of times, and
replaced
the resistors a few times as well. This happened quite often in the wee
morning
hours on the bench after 16 hours or so trying to make sense out of some
newfangled solid state transceiver.
If you think it'll work, I'll draw a crude schematic and e-mail it to
you.

Old Chief Lynn

wrote in message
...
Hi,

I just bought a Lampkin 107C Service Monitor. It has an accessory
that I didn't get. It's the 20DB attenuator pad (part No. FAP-20).
Does someone have a schematic available so I can build one? I'd also
buy the unit itself.

Thanks,

Jim