Note that all of this depends on how accurate you need impedance
measurements to be.
The metal film resistors will work reasonably for calibration if all you
need is general log-mag S11, SWR, or looking at the general shape and value
of the loss curve / impedance curve for a choke or core. Especially at
frequencies less than 30MHz. If you need accurate impedance measurements,
then the calibration accuracy is more important.
I would order the 805's, but start with the metal film. Then when the 805s
arrive, do a comparison of the difference in measurement you get with the
new calibration. Depending on your specific use case, it may not change
much. Note that in the banana-plug test fixture you plan to use, there are
lots of non-ideal factors at play - so making one factor ideal may not have
as much effect as hoped.
Stan
On Wed, Mar 22, 2023 at 11:06?AM Roger Need via groups.io <sailtamarack=
[email protected]> wrote:
On Wed, Mar 22, 2023 at 11:00 AM, Steve Johnson wrote:
Thanks for the info. I am only interested in frequencies up to 60 mHz
(typical ham radio stuff on HF bands). I¡¯ll have to order those 805
surface
mount resistors. I have some old-school metal film leaded 100 ohm
resistors¡ª maybe I could use those if I trim the leads very short?
The metal film leaded have some internal inductance due to the way they
are trimmed.
Roger
