Re: LF: RE: Todmorden receiver

[Paul Nicholson <vlf0403@abelian.org>]

Some amplitude calibration runs on the H rx yesterday
around midday.  At the same time measured the cross-talk
between the two channels.  At 8030 Hz:

 N/S to E/W -58.7 dB
 E/W to N/S -44.2 dB

which is a great improvement on the previous rx, which
was no better than -30 dB.   This is through ensuring
that the impedance from each leg of each balanced pair to
ground are well matched - at both ends of the downlink
cable.

About to run E rx amplitude cal, I'll try to get
that done before Stefan's EbNaut starts at 15:30.

First indications are that the noise is still high on
the H rx: S/Ns are often lower than the E field.

48V supply parts arrived the other day and work well.
No starting problems even with 60 ohms series resistance
using one of these


https://uk.rs-online.com/web/p/embedded-switch-mode-power-supplies-smps/1065848/

and

 https://uk.rs-online.com/web/p/isolated-dc-dc-converters/1227019/

That PSU is adjustable up to 55V which is useful.

So in the next couple of days, both rxs will come indoors for
a PSU upgrade.

--
Paul Nicholson
--