Hi chaps,

Is there a way of determining what basically amounts to S-parameters
for BJTs without resorting to a hard-to-get VNA? Some way of doing the
job just with the more usual test equipment you have around?
(scope/sig-gen etc.)

p.
--

"What is now proved was once only imagin'd." - William Blake, 1793.

"Paul Burridge" a écrit dans le
message de news
Hi chaps,

Is there a way of determining what basically amounts to
S-parameters
for BJTs without resorting to a hard-to-get VNA? Some way of
doing the
job just with the more usual test equipment you have around?
(scope/sig-gen etc.)

p.
--

"What is now proved was once only imagin'd." - William Blake,
1793.
You can use a Vector Voltmeter like the HP8405A (up to 1300 MHz),
and a signal generator. The test will be done on a single
frequency but the 8405 support some low manually sweep of the
frequency to cover the bandwith you test.
A 8405 can be found at cheap prices and is cheapest than a VNA.

"Paul Burridge" wrote in message
news
Hi chaps,

Is there a way of determining what basically amounts to S-parameters
for BJTs without resorting to a hard-to-get VNA? Some way of doing the
job just with the more usual test equipment you have around?
(scope/sig-gen etc.)
p.
--
"What is now proved was once only imagin'd." - William Blake, 1793.

I'd consider one of the common antenna impedance analyzers, but I don' know
what the output level is. Scope & sig gen is asking a lot unless you think
you can measure RF voltage and current magnitudes and phase while driving
the device with its "normal" signal level.
If you are talking about RF power transistors, the pros use matching devices
like shorted stubs and stretch lines to get power out, then remove the
device and measure the matching networks with the available equipment. Good
luck.
--
Steve N, K,9;d, c. i My email has no u's.

Check out the article 'A Low-Cost 100 MHz Vector Network Analyzer with USB
Interface' in the July/August 2004 issue of QEX, for measuring S pars.

Al, w6wqc