80/40 HWEF looking good!

Cut the wire in between the transformer and the 40m L/C trap with 30cm and the dip was spot on. Resonance on 80m was still a little low (around 3.6 MHz) so I cut the tail wire after the trap with 20cm and folded back 10cm. Here are the results!

Now that’s a pretty picture… Let’s zoom in:

Because the half wave for 80m effectively is loaded with a 20 uH coil the bandwidth is a little small but still under 1:3 on the whole band and 1:1.45 at best. I found that the R of the antenne on both 80m and 40m is a little over 50 Ohms so I will probably add a turn or two to the transformer. Not sure which one I’m going to use though. I might first want to try the multicore transformer configured from 2 x FT140-52 and 4 x FT82-52 inside but I might as well be using the single FT240-52 transformer with 4:28 or even 5:35 ratio. Here’s what 40m looks like:\

Nice! Better the 1:1.7 on the whole band. Also here the R is a little too high so a little more transformation is required. Will do that later, first test this to see how it works.

I’ll keep you posted!

73 Pleun (PA3HHO)

Working on the 80/40 HWEF again…

I tried to span away 40 meters (120 ft) of wire in an effort to do some testing on a wideband antenna (the well known full-size 80 – 10 version) but I just don’t get away with the length. I have to zig-zag all over the place and when I tested it with one of my auto transformers, the resonance on 80m (half wave) was too low and on 40m (where it’s a full wave) too high. Shortening the wire would improve on 80m, but will move the resonance point on 40m even higher so that’s a dead end.

While I decided to opt for a dedicated 80/40 aerial AND a dedicated 20/15/10 antenna (wire or vertical), I’m taking the wire down again and will replace it with a single trap for 40m. Because I’m not sure how much inductance the trap needs to get a “practical” tail wire (around 10 meters long, that I can span away), I decided to make a quick and dirty trap just temporarily. When I’m happy with the performance, I might be making a more permanent solution but experience learns that in many cases, my temporary solutions become semi-permanent HI.

I took one of my old trap coils that’s wound on a Fritzel isolator. It’s about 40 turns of enameld wire .8 mm in diameter. Because I hate to remove and add turns to a coil to get resonance when using a Russian door knob type capacitor, I decided to just leave the coil fixed and cut a piece of normal 2 conductor home appliance wire to length.

The coil measured around 22 uH. With 31cm of wire that measured 22 pF (so .7 pF per cm) I found resonance around 7,646 MHz. I know my L/C meter measures capacitance pretty well, sometimes I doubt the inducatance measurements. Calculating back from the resonance frequency and the capacity, the coil calculates to 19,9 uH, not bad. I used that value to calculate required capacity for resonance around 7.3 MHz which is 23,9 pF. To get 24 pF, 34cm of wire required. It’s nice to see that – now and then – theory matches practice HI:

I think I had 20 meters of antenne wire lying around from my previous experiments, I’m going to hook that up to an auto transformer (for testing I mostly use the one with 2:14 ratio on single FT240-43 with single FT140-43 inside), hook up the trap on the other and and a random length tail of about 12 meters and let’s see if I can get it nicely in tune on 80m and 40m. First test looks very promising:

Going to cut the length of the wire between the transformer and the trap about 20 cm to get a dip around 7.1 MHz (now a little under 7 MHz), that will move the dip on 80m up as well, maybe it’s spot on.

Will keep you updated!

73 Pleun (PA3HHO)

 

 

Trapped HWEF for 20/15/10

Today I spend almost whole day cutting my 20 – 10 HWEF to length and running up and down the stairs (shack to garden and vice versa). The auto transformer is based on a single FT240-52 with 2:14 ratio. The wire has a trap for 10m and a trap for 15m. I will measure the exact lengths in future, probably will add another page on it in the HWEF menu.

The antenna wire is sloping in a steep angle down from my roof, I was hoping it would have a but lower radiation angle that way then the 80/40 HWEF that I used on 20 as well (that when is lightly sloping, almost horizontal). I will experiment with different directions and angles. The results so far:

20 meters is looking good!

 

I still need to shorten the wire in between the 10m and 15m a little to get the dip around 21.250 but for now it’s fine. Shortening this wire will also have impact on 20m so I will have to lengthen the tail wire.

I had a nice dip around 28.500 MHz with very low SWR, but for some reason the R went up to 65 Ohms and the SWR went up, not sure why. Still very acceptable for the SSB part of the band.

For now I’m happy, will be doing some testing the comings days. I’ll keep you updated!

73 Pleun (PA3HHO)

Bye bye Yaesu, hello Icom IC-7100!

The holidays are here so time for playing radio. Because of Corona, we have our caravan set up on a farm with friends a couple of miles away and we can go there whevere we feel like it (or stay at home if we want to), really ideal.

I’ve had many “holiday radios”; Kenwood TS-50, Yaesu FT-707, FT-897D, FT817D, FT450D, FT-991 but for some reason I just didn’t like ‘m very much. They did the job, but for some reason I always felt it was a struggle to work with. Last year I bought a Yaesu FT-891, a simple HF radio. I didn’t do much VHF/UHF and for listening to the local repeater the Yaesu FT-65 was good enough. I still think that for the price (around €550 with cashback rebate), that radio just can’t be beat. The performance is great and the DSP functions work great too. The reception sound reminded me of my trusty FT-2000 I once had. IF frequencies of the FT-891 are the same as the FT-950 / FT-2000 so I wouldn’t be surprised the FT-891 leans on those predecessors technology wise. I didn’t have VHF / UHF in my shack and used a cheap 2m transverter for a while but missed out on the 70cm fun. Therefore I bought a Yaesu FTM-100D and even though it worked and sounded fine, I didn’t have a click with it. Then I started watching some videos on Youtube and found that the IC-7100 has a lot in common with the IC-7300 (or vice versa actually). I really love the intuitive controls and decided to sell the FT-891 and trade in the FTM-1000D on a brand new IC-7100.

I’ve been looking for one for years but always thought it was too expensive, but after all those radios, it’s finally here. I’m really impressed this far. I first hooked it up to the Diamond V-2000 for 6m / 2m / 70cm (and listening on 70 MHz / 4m which is allowed over here), really fun. I’ve now connected it to my (at this moment not so resonant) HWEF via the LDG AT-200Pro tuner (tunes a knitting needle) and enjoying some QSO’s on HF. I must say I’m really impressed and – I will be shot for this – It’s not so different on HF then what I’m used to on the IC-7300. I really like this radio. The fact that it doesn’t have a built-in tuner is not an issue at all for under €200 you can buy a nice LDG tuner, I’m considering buying the AT-7000 which can be controlled via the IC-7100’s control head. Really happy… Now let’s wrap a trap for 40m and cut the 20/15/10 HWEF to length, see if I can catch any DX when the antennas are optimised. Here’s a short video that shows how well the NB (noise blanker) is working, especially compared to older radios.

73 Pleun (PA3HHO)

HWEF mix 52 material core experiments

It’s been a while… I’ve been busy with work and family but now the holidays are here, I have some time to play radio again.

Past months I’ve been experimenting with a mix 52 multicore transformer built of two FT140-52’s with four FT82-52’s inside. Total Al value of this configuration is 1170 and the transformer has a turn ratio of 3:21. According to Owen Duffy’s Calculate ferrite cored inductor (from Al), the efficiency on 3.6 MHz is 99.5% meaning 0.02 dB loss. I must be doing something wrong HI (I asked Owen, hopefully he’ll get to me soon).

I took the trapped wire from my 80/40 HWEF down and tried to span away 40 meters of wire. The last 10 – 12 meters are going down 6 meters from a tree, then 3 meters to the left in parallel to my (metal!) fence and then 4 meters up again so the aerial’s “tail” has a triangle shape. On paper it looked good, but in practice it’s really not. Resonance on 80m is OK, too high on 40m and 20m. I also noticed that the R went down when frequency went up. Op 80m the R was around 35 Ohms, on 40m and 20m it was around 25. Not a real problem for now, changing the transformer ratio will probably fix that. I tried to compensate the (terrible!) performance on 20, 15 and 10 meters by adding 22 pF, 69 pF, 100 pF, 122 pF and 147 pF but this didn’t seem to improve things.

Conclusion: the 6-core transformer will probably work well on 80/40 but the bandwidth is too narrow to use it on higher frequencies. This didn’t come as a surprise because the total Al value of the cores was around 1170 which with 3 primary turns results in 10.53 uH inductance, that’s even higher than 3 turns on a single FT-240-43. Even though the efficiency of the 43 material might not be optimal, it seems that the lower Q allows for more bandwidth making it still a good allround solution for a 100W wideband HWEF. If you need decent performance, use 3:21 ratio on a single FT240-43 when 80m & 40m are your favorite bands and use 2:14 ratio for decent performance on 80 – 10 meters (optimum on 40 and 20 meters)

Coming weeks I will be testing my 20/15/10 HWEF that’s using a single FT240-52 core with 2:14 ratio. It now has a 15m and 10m L/C trap with moderate inductors, total length is around 7 – 8 meters. I also started experimenting with a new transformer that has a 4:28 ratio on a single FT240-52 core. I’m hoping to use that on 80 and 40 meters. I already did some testing and found that, without compensation capacitor on the input, it only seems to work well on 80 and 40 which is fine for my purpose. I will add a 40m trap to the wire to enforce the antenna is half a wavelength on both 40m (trap electrically disconnects the tail wire) and 80m.

I will keep you updated! Stay safe everybody!

73 Pleun (PA3HHO)