I coverted the Sirio New Tornado to 20m and let it run WSPR (5 Watts) for less than a day. I’m really happy with the results, also Austrasia seem to be picking up the signal, that was what I was after. Check for yourself:
I’ve reduced power now from 5% (5 Watts) to 0% (0.5 Watt), map looks very similar. Here’s the top of the result list from wsprnet.org:
Good news! Today I spend some time getting the Sirio New Tornado CB antenna to work on 20m and guess what? It works great! Replaced the wire by a straight piece of wire, set radiator to 6.9 meter length (22.7′) and radials to (6.6′) and put it on the roof. Note that the antenna needs to be at least 5 meters above ground level to get the impedance down to 50 Ohms.
A couple of weeks ago we had a South-Western storm and I had to take the 20-15-10 HWEF vertical down. It’s too top heavy for permanent installation but makes an excellent holiday / field day antenna so I will continue the experiment.
With the PACC contest coming up in Februari and my long lasting desire to have “something vertically” on my roof so finally free sight in N-E, N and S-E direction (e.g. Asia), I started looking for alternatives. The old trap loaded HyGain AV-12AVQ vertical was no success; traps were faulty and I had a problem putting away decent length radials / radial wires. I looked for a new one but found them to be too expensive and I would still have the problem with the radials.
I’ve found an easy modification to get this antenna working as a monoband vertical on 20m with very promising figures, and I’m working on a way to make it at least a dual band antenna for use on 10m as well (undo the modification). Check the article, it will be updated in the future when I have done more experiments.
Because my holiday HWEF pages (originally in Dutch) get a lot of international visits, I decided to translate them in English. Please be aware these pages are from 2012/2013 so a little outdated, but probably still inspiring to some people. Built yourself a vertical 40-20-10 HWEF of only 7 meters long and have some radio fun on your holidays!
I’ve converted the calculations from Owen Duffy’s ” Calculate ferrite cored inductor (from Al)” into an Excel spreadsheet. The spreadsheet holds tabs for the most popular toroids. All manufacturer’s material and frequency specific parameters are pre-filled in. I want to share my spreadsheet with you, you can download it from my pages for personal use. Please do not distribute without written permission. There’s no need anyway, you can always download it from this blog. This version 1.03 was updated 2 November 2020. Click link below to download: HWEF transformer toroid calculations V1.03
I’ve recently put my vertical HWEF for 20/15/10 on my roof. It seems to be working better than I could hope. I’ve updated the article so if you want to know the history and details, check this article (also accessible via the HWEF menu):
Today I made a new transformer for my dual band 80/40 HWEF. After all the experiments with 52 toroids, I came to the conclusion that even though the efficiency of this mix is very good, it’s not suitable for lower frequencies.
Of all the candidates, I chose a single (big!) FT290-43 toroid with a 3:21 turn ratio wound with AWG 15 (1.4mm) wire. There’s plenty of magnetising inductance so no problems with the insertion VSWR on 80 meters, it might even work reasonably well on 160.
If you’re interested, read the whole article: 80/40 HWEF.
As I’m ordering toroids at mouser.com at certain quantities to get a better price, I have a little too much stock right now so I’m selling some to fellow radio amateurs. If you need just a few, I can send you some. If you need higher quantities, you might be better off ordering directly from Mouser.com yourself. Note that prices on the Mouser website are excluding VAT and €20 shipping costs! I can ship within Europe via PostNL (with track & trace and insurance) or you can pick ‘m up at my QTH for a free coffee and a good conversation HI.
FT290-43 €10 (160/80/40 HWEF transformer) FT240-43 €7 (allround 80-10 HWEF transformer or G3TXQ 3-8 MHz common mode choke) FT140-43 €3 (40-10 HWEF transformer, common mode choke experiments) FT240-52 €8 (20-10 HWEF transformer G3TXQ 14-30 MHz common mode choke) FT140-52 €4 (15-10 QRP HWEF transformer, common mode choke experiments)
Send email to pa3hho @ gmail.com if you want some.
As the optimum VWSR curve of my 2 x FT240-43 transformer with 3:21 ratio was around 3.5 MHz (VSWR 1.1:1) and the VSWR on 7 MHz was already 1.7:1 I decided to order some (bigger) FT290-43 toroids. I think for the lower frequency bands, 43 is still the way to go. The 52 material needs too much turns to get enough magnetising inductance and then flux leakage seems to become a problem. For 40m it might be OK, but not for 80m.
Some FT290-43’s with FT240-43 and FT140-43 for comparison
I’ve made a 3:21 ratio transformer with a single FT290-43 and the VSWR curve is nice and flat from 3 – 8 MHz: 1.1:1. Seems like this might be the ideal candidate for my 80/40 HWEF. The calculated core loss is 0.6 dB on 80m and 0.5 dB on 40m so efficiency around 87% – 90% which I think is acceptable.
I have way too much toroids lying around the shack at this moment so if you need some, I’m willing to sell you some from my private stash. I have FT240-52’s and FT140-52’s, FT240-43’s and FT140-43’s and I might even sell some of the FT290-43’s. Drop me a line if you’re interested. I can ship within Europe I guess.
Some time ago I was wondering if there were any updates on Steve Hunt’s (G3TXQ) common mode choke measurements because the information I was using, originated back from 2012 already. I was sad to find an in memoriam article on GM3SEK’s blog of 1st of January 2019 announcing that G3TXQ passed away. I’ve been using and G3TXQ’s recipes for my CM chokes and promoted it with many other fellow hams so may his name and callsign be remembered! From now on, I’m calling them TXQ chokes.
G3TXQ’s 2015 chart of some good common mode chokes (and some very bad ones)
I’ve been using 17t on single FT240-43 for many years for my 40/80 antennas (the 2nd one in the chart) and 11 turns on 2 x FT240-52 on my antennas for 14 MHz and higher frequencies (the 7th in the chart). Looking at the chart, these configurations still seem to be the best choice but G3TXQ has added some interesting new configurations e.g. the 9 turns on 3 x FT240-52 that has greater than 8k impedance up to 30 MHz. I’m thinking of using that one in future for 14 MHz and up.
Within the online amateur radio community a design using multiple FT240-31 toroids has become popular. This is kind of contradicting G3TXQ’s measurements because it seems that he only found one decent solution using 31 material for 160m and 80m. All other 31 material based designs that did appear in the 2012 chart (below) were dropped in the 2015 chart probably because the figures weren’t too good. Not sure why this design has become so popular and what the theory behind it is but I reckon that if you put a number of mediocre chokes in series, it will probably make one good choke HI. I rather stick with the G3TXQ designs though, simple and effective. Here’s G3TXQ’s chart from 2012 for reference.
G3TXQ’s chart from 2012 showing some designs using 31 material
PA3HHO's 