Thanks to John, Joe and Mike for the feedback. Mike hit it on the head when he
mentioned the slide switches. It was oxidisation and some vigorous switch
gymnastics cured it. I now have readings that complement John's matrix. I know
right well I should have guessed this, but I knee-jerked as
2-Port VNWA measurements at 7MHz
Switch, VSWR, dB
0 1.01 0.07
1 1.03 1.06
1 1.03 1.06
3 1.02 3.08
6 1.03 6.31
10 1.02 9.78
20 1.05 19.97
VSWR approaches 1.1 at 30MHz with some switch settings.
John KN5L
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Looking at the AT1 manual, the switches and traces are certainly
not 50 Ohm transmission lines. As such, one gets all kinds of
stray behavior. While you do not say at what frequency or range
of frequencies you made your test, I would suspect you will see
higher SWR as one goes up in frequency
Hi Steve,
Each attenuator section is designed
to present a 50 ohm input impedance
when terminated in 50 ohms. Of
course that will change as frequency
is increased and inductive effects
take greater prominence.
At what frequency(ies) did you
make your measurements?
What were the actual SWR
I have purchased a second user AT1 recently, largely due to the ruinous
TransAtlantic logistics costs, but also the ongoing absence of any support here
in The UK.
Although purely from observation of the circuit topology it seems reasonable to
assume that it is not a constant impedance array of
I have an at1.
How do I tell on from off for each switch, and what are the values of each
switch?
Totally blind, so need a little help.
Thanks and 73.
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to the left
and right (switches toward you), the attenuation values left to right are
1,1,3,6,10 and 20 dB
73 - Mike WA8BXN
---Original Message---
From: Gary Lee
Date: 4/23/2010 10:18:20 PM
To: elecraft list
Subject: [Elecraft] at1 attenuator questions
I have an at1
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