Strapped feeder results (630m), and back on 10m

Overnight I have been on 474.2kHz WSPR using the VHF/HF antennas all strapped together and tuned against mains earth. Impressions are that it performs about as well (or badly?) as the low height dedicated Marconi, perhaps a tad better? Strapping feeders is certainly easy to do.

Since about 0820z I have returned to 10m WSPR using around 2W to the Par end-fed antenna. Reports already exchanged with Japan and Reunion Is. in the Indian Ocean. Conditions still look excellent on 10m with a sunspot count of 139 currently. 10m, even with my antenna and 2W, is too easy right now!

10m - first hour with 2W to Par antenna

474.2kHz - trying strapped feeders

As a last attempt (for now) on 474.2kHz WSPR this evening I have strapped the feeders of the Par 10/20/40, the 2m halo and the V2000 tri-band VHF/UHF vertical all together and am tuning it against mains ground to see how things compare with previous tests. The "theory" is the effective vertical is about 2x higher so, if efficiency was about the same as before, the ERP would be up. In reality, the antenna current is only 10% higher so losses over the "short" Marconi must be much greater.

So far, spots of other stations appear stronger (e.g.G3XIZ -1dB S/N) but I've only managed 2 spots of my own signal, these from PA3ABK/2 in Holland at 306km. These are not brilliant, but similar to the earlier tests. More results overnight tonight.

Tomorrow I may go back to 10m.

13 unique spots of my QRPP 474.2kHz WSPR so far

So far, 13 unique WSPR spots of my signal with the very low Marconi antenna and 5-10mW ERP. Plenty of further spots likely although I want to change the antenna to ground the far end shortly. All my current experiments are with antennas I can string out without having to use a ladder (because of my mobility issues - stroke).

Best DX remains DL4RAJ (990km) although plenty of spots received from DL-SWL (701km) overnight too.

472kHz ERP over-estimates?

Looking at the reports I send and receive, I wonder if several stations are actually using a LOWER ERP than they think? From measurements I am pretty sure my ERP is 5-10mW with 5mW likely to be the closer figure. Some stations claim 0.5 to 1W ERP which is considerably more than me. Some stations ARE using 6-12dB more than me and to much better antennas but, judging by reports, I should be reporting them much stronger than I do. This could be because (1) my noise floor is worse, (2) my RX is not optimally sensitive, or (3) their ERP is lower than they think. In at least some cases (3) is the reason.

Nearest 474.2kHz report

This afternoon I received a MASSIVE +12dB S/N 474.2kHz WSPR report from G4PZW who is located about 1km  (or less) from here. He is in the same QTH square (JO02dg).  I met Rob for the first time last weekend at the Burwell Hobbies and Interests Weekend when he was signing GB1BHW, a special event call.

New seasonal DX record on 474.2kHz last night

Last night I received several spots from DL4RAJ at 990km,which is a record, so far this year, for my QRP WSPR signals on 474.2kHz. I am hopeful of better results yet.

My 10mW EIRP maybe be a bit over-estimated as I forgot to divide the measured voltage by 1.414 to convert to RMS from peak. This means my ERP was closer to 5mW, even lower than I had expected, even though I am still showing 10mW ERP on WSPRnet.. This proves, even more, that high power and fancy big antennas are NOT needed to have fun on 474.2kHz MF.

12 unique WSPR spots in last 24 hrs with QRPP on 474.2kHz

EIRP calculation on 472kHz band

So I plugged my measured figures into the equations to work out ERP on the 472kHz band with the very low height Marconi.  Measured antenna current is 0.64A and effective height about 1.6m.  The formula gives EIRP taking  into account the lack of directivity.

EIPR (472kHz) = I^^2 * Heffective^^2 /100  (source LF Today 3rd edition)
                          = 0.64*0.64*1.6*1.6 / 100 = 10.48mW

ERP is 1.8/2.52 times the above figure, so around 7.5mW.

My estimate of 10mW  ERP is a few dB too high, but not a bad estimate, considering experimental error.

As the ERP is proportional to current and effective height both squared, it is easy to see how ERP can be much improved by increased antenna vertical height, increasing the power, or doing both. The other thing is to reduce system losses.  An antenna/earth that looks like 300 ohms is probably lossy.

Sputnik days

A message from Oleg RV3GM :

Dear Sputnik'ers

Welcome to "Vanguard-1 QRPp Party 2014"
Dates - March 17 to April 7.
This is not a contest but activity days only. Enjoy milliwatting using old type
Ge transistors TX. See details here -
http://club72.su/vanguard.html

Wish you all the best, 72!
Oleg "Mr. 72" RV3GM / KH6OB
=== In QRP We Trust ===

Very Low Marconi on 472kHz

As from mid-afternoon I am now using a very low height Marconi on 472kHz, tuned against the mains earth (that attaches to a decent ground). The average top horizontal section height is about 1.8m with a horizontal length - a wire along the top of a fence and trellis in an L-shape with a length of around 30m. The whole antenna is just about invisible. The vertical section is just the wire up to the top of the  fence.

The whole antenna resonates with a 108uH inductance in series (wound on 110m diam. former) and this is matched to the 12W RF out transverter with a 42mm diameter 3C90 tapped toroid. The antenna looks like 300-400 ohms and the antenna current is 0.64A measured with my current meter. I have ESTIMATED ERP as around 10mW but am probably in a position to calculate this now.

Performance of the very low Marconi compared with the 15m earth-electrode antenna, is about 6-7dB better over probable ground wave paths. So far, the only skywave signal suggests a less noticeable improvement, I think.

Ofcom and UK Spectrum Sales

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/287994/UK_Spectrum_Strategy_FINAL.pdf

My reading of this OFCOM document is that the UK frequency spectrum is seen as a opportunity for revenue generation. Apparently spectrum "resource" is worth £52 billion to the UK economy.   BTW, amateur radio doesn't even get a mention! Radio amateurs do not contribute to this revenue stream and the document  does not seem to recognise the self training of radio amateurs in radio science. Maybe they are right: using a black box  is hardly skillful or educational.

To my way of thinking, spectrum is a NATURAL resource, a bit like the air we breath or the wind in our faces. Call me an old fashioned socialist (actually this is NOT my natural political stance) but I am uncomfortable that MONEY seems the main, actually the only,  motive here.

Give radio amateurs very easy access to "strange" spectrum  (e.g. sub 8.3kHz,  around 73kHz, and around 40MHz) and access to all licence free slots. Actually, radio amateurs have a lot to contribute and self training in radio science would be ENCOURAGED by such moves.

We are more likely to gain 146-147MHz which, frankly,  is a waste: we will gain NOTHING from this except maybe yet more appliance operators using black boxes. 2m is never that busy in my experience. How often are FM channels busy or the SSB slot? Outside contests SSB seems pretty dead on 2m.

We all have a duty to use spectrum wisely, but money is surely not the right way?  I am also ANNOYED that so much power and spectrum is in the hands of the UK military. Just look at the current frequency allocations. This is plain wrong in peacetime.