On 13/04/2023 20:07, Greene,David J wrote:
Hi folks,
I've had a set of N200 and N210 radios with SBX daughterboards for a
number of years now. It has become quite common that I need to either
remove the bulkhead cable (at the daughterboard) when using the
daughterboard calibration scripts or replace the bulkhead cable all
together; otherwise, there is residual IQ imbalance (sometimes as much
as 30%) and DC offset. I perform calibrations about every week.
I understand the calibration scripts utilize the internal leakage in
the daughterboard, but what's going on here, are the cables aging?
I've noticed, over time, that metallic dust becomes embedded around
the insulator at the end of the cable. I've started to routinely clean
the female ends of the bulkhead connectors with compressed air to
remove the dust.
Is there any other maintenance I should be aware of - any ancient RF
wisdom someone would be willing to pass down? It's much appreciated.
All the best,
David Greene
University of Florida
Conventional wisdom in calibration labs and places like radio
observatories is that each part of an SMA connector gets cleaned with
an alcohol wipe and allowed to dry before connecting. I've never
done that :)
SMA connectors also aren't generally rated for a lot of
connect/disconnect cycles, so when I expect to have to do this, I usually
have a "sacrificial" intermediate connector that can take all the
abuse and only require replacement once in a while, reducing
the number of cycles on the main connector.
I'm surprised that you need to re-cal the I/Q balance that often, but if
you are operating under different temperature conditions,
I can see that being a requirement.
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