Active antenna

I have finally got my active antenna connected. This is an old Dressler ARA-60 that officially covers 100kHz (50kHz ?) to 60MHz with a substantial gain, and a decent dynamic range.

First things first. Using this antenna while transmitting does not work very well. No surprise there I have my 10m vertical about 5m from the active antenna, so it is, of course heavily overloaded when transmitting 100W on 10. All true signals simply disappear. No, I am not disappointed, I was expecting that, even with my 3W CW, that I use mostly on the HF bands with a dipole, overloads the amplifier.
Similarly, the medium wave broadcast signals tend to generate IMD in the receivers on frequencies below 500kHz. At least, that is how I interpret all the apparent spurious carriers on those low frequencies.
Also, I am not yet using the original power inserter (connectors have to be provided), so I am using a simplified power inserter with a high value inductor. This works fine on MF/LF, but, unsurprisingly the inductor appears to have some resonant frequencies, making the gain vary over the (large) frequency range. I suspect that when I get the correct power inserter ready that will change.

I am splitting the signal from the antenna into ~>49MHz and ~<30MHz, using a commercially available diplexer. The >49MHz signal is then entered into a broadband power splitter (3 outputs), going to scanner receivers. One goes to a multimode scanner, listening to beacons, meteor scatter from TV transmitters, SSB, CW etc. and the other to an FM scanner receiver. The <30MHz goes via a 4-way satellite TV signal splitter to (at the moment) a single HF receiver covering  ~0 - 32 MHz. Things work nicely, and I have good signals on all HF bands - noise level is rather high on some frequencies. On 600m the signals through the splitter are still quite sufficient, although there seems to be some IMD present. I expect to use this setup later for QRSS and WSPR monitoring, most likely with simple home made receivers.

It will probably be a good idea to split the frequencies further, e.g. with a low pass/high pass filter centered around 500kHz, in order to remove the MW band signals from the receiver for the lower frequencies.

Now, just listening, the antenna provided a nice surprise. The spec tells me that the antenna is good up to 60MHz, but the "local" beacon on 70 MHz (about 40 - 50km away) comes in nicely. The receiver set up for the 70MHz FM calling frequency of 70.450MHz suddenly came to life, and a station about 180km away appeared on frequency via tropospheric propagation (tropo).

All in all this is a nice generally applicable receiving antenna. The limitations are clear to me, but it presents a good compromise until I can improve the antenna system, and is good for general LF/MF/HF/6m/4m monitoring.


10m in October

Late September I got my half wave vertical for 10m mounted with the feed point about 7m above ground.

This seems to have been good timing because that was about the time that the band started opening, at the time mostly in the North-South directions.
As October has passed, this has expanded to most of the world, and I have had the pleasure of working 6 continents. Antarctica is the one missing, it was active, but I could not get it. Maybe later.

As of today the country count is up to 56 in 6 continents on 10m alone. Not bad for a low Solar Cycle and a vertical. I suspect that, if the solar flux keeps up, we will have mostly daily F2 openings on the band until March/April. Several days we have had openings into the Mediterranean, i.e. down to about 2000km, indicating a relatively high MUF, albeit not enough to have 6m open. On 6 there is always the small hope of a few TEP openings around the Equinox.

I am now going to be listening to the low frequencies, especially during the dark hours which are aplenty here in the next few months - and probably try some low power work at the lower HF bands. After all, 10m is not very much open during those hours in the winter season of the current Solar Cycle, except for a few sporadic E openings in December and January.

I am still waiting for VK and ZL. I have heard them, but not yet being able to work them.