2021-04-15

Ground connection for the Mini Whip. RX Test.

 I have a ground rod on the Mini Whip now. Not too far into the ground, about 60cm/2ft. Hammering a 2m (8.5ft) ground rod is tricky without the right tools ;)

The results are interesting:

A relatively detailed review was done today, by dialing slowly through the bands. Starting downwards from around 18MHz indicates that the sensitivity/SNR has improved reception on frequencies from about 1.8MHz up to 18.2MHz, maybe higher.

Medium wave is not bad, with signals on essentially every channel in the whole band, with a reasonable SNR, probably increased sensitivity.

NDB band appears noticable worse wrt SNR, possibly partly due to overload from MW stations in the evening, but noise level seems to have increased.

LW seems OK, not spectacular.

VLF (<100kHz) seems more sensitive, but with more noise. possibly due to overload of the RX. 

A different Mini-Whip with a real whip antenna (1 - 3m long) might improve sensitivity on VLF/NDB bands, but should probably have a low pass filter with a 3dB cut-off frequency of 530kHz. Because a thin whip mounted low is not too visible I might add this to my antenna farm, just to see how it works. If it works well I can make a permanent installation.

Because the Mini Whip is very broadband it may be an advantage to make some filters in any case, possibly as follows:

Low pass with 150kHz 3dB point, for the 136kHz amateur band and "VLF" reception.
Band pass with 150kHz high pass and 530kHz low pass, mainly for the NDB/marine bands and 472kHz amateur band.
MW band pass with 530kHz high pass and 1700kHz low pass.
MF band pass with 1700kHz high pass and 3MHz low pass, mainly for the 1.8MHz amateur band.
HF band with 3MHz high pass filter.

If I get all working nicely I may make a (set of) distribution networks, possibly with switches for the different receivers.

Yes, I like monitoring a lot of frequencies I do have some receivers, everything from purchased amateur equipment to portable transistor radio(s) with external antenna input(s), and, of course some SDRs, and some simple monitor receivers (e.g. a Pixie kit for 40m), and some that I may build. At some time I have been monitoring (audio or data) on 14 different frequencies simultaneously, part of it as monitoring propagation, and I expect this record to be beaten ;)

This is also part of my intention to make a contact on as many bands as possible with (at least partly) home made equipment.

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