Thanks for the kind compliment Matthias.

@@Jonny10001 Your welcome! You are a RF magician 😉 Much love, Matthias ( 73 from DL1NDG )

Hi James, you would need to do the calculations to scale it up in size for that frequency, I couldn't help you with that.

Thanks for your comment,👍

Hi Brendan, it’s still up on the mast and working as well as the day I installed it, thanks for the comment.

Hi, thanks for the compliment

Thanks for your kind words.

Thanks

Hi, most ATV repeater antennas are horizontally polarised so it’s not so easy to receive 360 degrees. Best to find out where your local ATV repeater is and aim a directional antenna in that direction on the amateur band it transmits on.

Thanks for the compliment on the video

Would love to time travel !!

We intend to go back and use a much higher antenna and hopefully power a portable radio, calculator or any other low current device.

@@Jonny10001 my friend did not live very close to the transmitter, fortunately modern calculators use very low power. With yor experiment you might be surprised just how little current it takes to light n LED dimly, far below 1mA.

Hi Paul, the original design called for varying the length of the small wire loop at the very top of the antenna. In practice the bandwidth of the antenna is so wide that a small loop that will fit under the top cap is all that's needed.

@@Jonny10001 Thank you, I’m guessing an inch’ish of the centre conductor will be adequate?

Hi John, I used 9913 coax, about 10 meters from the antenna to the receiver. The 23cm band seems to propagate much better then most people realise. I was was able to receive the distant beacon with the antenna inside the shack when testing even though there was a brick wall in front and a metal roof above!

@@Jonny10001 Thanks very much for the reply!.. Ok I thought the coax would be something like that. I did a lot of S-Band work when there was such a thing as an Molniya orbiting AMSAT and pretty much 9913 was a min so I have some about the place. Yes 23cm interesting band, have been building a UHF tripler using a triode and can trigger a repeater with the output connected directly to a big fat dummy load, go figure. Great video thanx again

I can’t quote an actual figure but it’s very low, at least at 23cm.

Thanks for the kind comment👍

I made the video over a period of time starting with one filter then another one at the end. It didn't seem to make a difference which side the connectors are on but I would stay with the original design to be safe. It could make a difference at higher frequencies.

Thank You 👍👍🤗👌

Thanks for the kind words, de John VK2ATU

What you say is true but for those that want to go DVB-T this is a "home brew" way of doing it. Our local ATV repeater has both DVB-S and DVB-T inputs. DVB-T does have an advantage in hilly terrain in reducing ghosting problems. The hardware way of producing DVB-T means just a power button is pushed to transmit. When software is used to produce DVB-S a series of tasks have to be undertaken with re-starts sometimes required.

The Terrestrial modulation just happens to be superior for Terrestrial applications :) Very nice to hear that your local repeater has both DVB-T and DVB-S inputs and that 23cm is getting used.

It would Graham but you need to resize it to suit the band you intend to use it with.

Hi Henry, thanks for the kind words. We have a Monday night net from 7:30 pm AEST till usually 9:00 pm. Voice talkback is on the 147.325 MHz + offset repeater.

No, only during the Monday night net or other times by group members.

@@Jonny10001 thanks! I watched it via the BATC website last week. Perhaps next week I can watch via RF :-)

@@5Perf65mm Hi Henry T, good to know your watching via the stream. Any 70cm amateur band yagi antenna will give you a good chance of receiving our ATV transmission. You don't have to be an amateur radio operator to text us on the BATC stream, let me know your watching and i'll give you a mention.

Thanks for the compliment 🤗

You have to scale the dimensions up by a factor of 8.4 but it then becomes to big to be practical. Have a look at helical filter designs, they suite the lower frequencies better.

HUGE !!!

1.3km long X 200mtr wide X 450mtr deep. The tuning screws are made from 30mtr threaded water pipe.

Watch Version 2 much lower level👍

The original article that the construction was based on is:- lea.hamradio.si/~s53mv/cavity/cavity.html

@@Jonny10001 Thank you for sharing this. Much appreciated.

Thanks for the kind words, live long and prosper...

When I began construction I didn’t know for sure that it would work, just trusting the original article. Thanks for the compliment.

Hi, I get many inquiries regarding using the filters on lower frequencies. The design came from a talented gentleman that did the original design and I have supplied the link to his web site. My video was intended just to show construction techniques to make the filters in the easiest way. It should be possible to scale the dimensions up but I don’t have the knowledge to do that. Having said that using basic maths to scale from 23cm to your required frequency would be a good start.

@@Jonny10001 🙏 for the reply…. Will hit the books! ….

Thanks for the comment, I have had a fascination with antennas since I was a little kid, the ability to project radio energy out into the ether, wow.

Hi and thanks for the compliment. I don’t make any to sell but you could scale up the dimensions for the frequency you require.

Can you have really exact parameters to build for 866 to 869mhz-

No, i’m just an amateur radio operator that likes to tinker, thanks for the compliment.