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Locked Re: Regenerative receivers and loop antennas


 

Well Done That Man!

There is a key point in comparing active loops by off-air signals that now you can appreciate. If you are in an average or bad urban setting then the noise floor is so high that you can't hear or assess the noise floor of the loops you are comparing. The only way is by using dummy loops and good signal generators in a screened environment - something that most people on You Tube don't do so their comparisons in noisy places cannot sort good from bad. But now you can tell !

The best reception that I have seen was at a BBC location, they had long Beverages in all directions that each had their own distribution amps. Each listening position has it's own very nice RX and a great big antenna switch. Their stock demo was to tune to a quiet-ish spot on MW. Turning the knob then revealed various local stations in the UK and Europe, the last position? was a provincial? broadcast from China - that was on a Winter afternoon before dusk.? Very nice to drive a receiver from a directional antenna system! I did emulate that with six Beverages in a Contest group. Being able to operate by rotating a directional antenna is a totally different way of operating radio, one tasted never forgotten.

It might now be worth thinking about some spaced loops, you can get some very nice directivity from 4 to 6 broadband loops with delay lines to beam form.? It is helpful to think of the delay from one loop to the other, don't think in phase but time. The delay time approach allows the performance to be more even over a wide frequency range. Using active loops or e-field antennas also has the huge advantage of zero interaction between the elements. Serious people have been using 6-10 element circular arrays for many years now, you get the multi Beverage like performance in a much smaller space but you do use a lot of coax and land in a very low visibility way!

Now that you have the great opportunity I would strongly recommend? ON4UN's book "Low Band DX'ing" from the Really Small Gas Board, It is the best of it's kind and has a lot of very good Antenna stuff. You might also consider something very low profile that works automatically in the background and gives you continuous world wide and band wide data, a WSPR station. An SDR like a Red Pitaya allows you to log 8 channels automatically and report back to the server via a LAN. Although you can also watch everything via the "wspr.rocks" app.? The "top spotters " section gives a score to spotters, currently I'm around 120th in the table, that's on an active loop 10m from my house and only four channels of RX. Bound to drop out of the top 200 now.

If you have a big smart TV then it's very nice to show a World map with all of your spots across all of the bands to visitors, it also shows when and where the bands are open. It's a good way of telling people what radio is about and impressing them? ( it impresses me too!) You can get the Map on wsprnet. org but the wspr.rocks map is much quicker and has some really great features. I often advocate using wspr reports as test gear, the SNR numbers are real measurements not deception meter guesses and you can compare your reports with others- or in your new situation - how much better yours are against the people left behind! But it's a very useful free tool, if you transmit wspr then you have hoards of spotters that can tell you how changes at your end alters their reception.

Your new QTH is very appropriate, it is in the district called South Hams!

best 73, Alan G8LCO

On 11/02/2023 14:35, Simon wrote:
Hi Alan

Simon g0zen

Have just moved from Dagenham to Bittaford inside the dartmoor national park..

Noise floor on 160-40 dropped from s7 to s1.( occasionally s3) .and thats on the Marconi T tx antenna ( still in progress, as currently only tx on 80m, matching network and 160 coil to be made)
Similar noise on the trapped 40-80 dipole.

Revelation though are the lz1aq¡¯s amps, crossed parallel loops and switchable delay line, ( 4 directions.) its as though nothing, UNTILL someone transmits, ok maybe s1 on meter but silly good sn ratio.

G0ZEN


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