On Thu, Feb 4, 2021 at 05:26 AM, schweppe wrote:
When looking at the front end of the nanovna you see a 10?F capacitor in
series with the MXD8641¨CSP4T Switch. This switch can resist 100V in
electrostatic discharge sensitivity testing (Machine Model). This test
is done with a loaded 200pF capacitor and a 0.5 ?H inductor in series.
A typical koaxcable (RG213 od RG58) with 100pF/m and 20m length will
have 20nF of capacitance. If this koax is loaded to 200V by
electrostatic, it will damage the MXD8641. Also if you measure an
outdoor antenna and there is electrostatic in the air, you may damage
your measuring equipment also.
It may be a good thing to protect your nanovna with ESD-diodes when
measuring long koaxcables and/or outdoor antennas.
73, DK5DN
Am 04.02.2021 um 10:30 schrieb Stephen Laurence:
Does this mean that a long length of coax can store/return dangerous (to the
vna) voltages, for example like a Tesla coil, or was the coax connected to
something at the other end?
Should we all be installing esd diodes to the port 1 input? Port 2 already
has a 14db attenuator. Is there a limit to the length we can measure?
Steve L
You could install a static drain resistor of several hundred K Ohms across the antenna terminals to keep static from building up. This is commonly done on shipboard wire antennas.
Ken