CQ-TV 273 is ready for download

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g8gtz
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CQ-TV 273 is ready for download

Post by g8gtz » Thu Oct 14, 2021 6:10 pm

Unfortunately due to a close family bereavement for our editor Frank M0AEU, the publication of the electronic and printed version of CQ-TV 273 is slightly later than usual but we are pleased to say that your electronic copy of CQ-TV 273 is now available for download on the BATC website at https://batc.org.uk/cq-tv/cq-tv-download/

In CQ-TV 273 you will find a report on our successful CAT21 part 1 meeting in August - and don't forget CAT21 part 2 takes place this weekend, see below for more details.

There is news of the IARU Region 1 ATV contest results - UK stations did really well with G8GTZ as overall contest winner, 3 UK stations were in the top 5 positions and UK stations won 6 bands out of 9. Congratulations also to M0YDH and G4XAT who won the BATC 2m and 4m contests run on the same weekend.

Mike G0MJW has written a guide to using OBS with your Pluto, Dave G8GKQ describes the RF Power Meter feature which has just been released in the Portsdown Test Equipment menu and there's details of a reliability update to the Portsdown 8 way switch.

Chris PA3CRX has written an excellent article on dishes and their feeds, Bernie G4HJW reveals details of a simple analogue dish alignment meter and Noel G8GTZ reminds us that it is the time of year to check that the neighbour's trees have not grown in front of your QO100 dish - note that there are only 2 days left to do this!

The printed version of CQ-TV 272, in full colour on high quality gloss paper, is currently at the printers and will be dispatched by the end of next week to those members who subscribe to the printed magazine.. If you currently don't receive the printed version, why not consider upgrading when you next renew your subscription?

And finally, we would really like more feedback on CQ-TV! Do you read it from cover to cover, are the articles relevant to you or do you just file it away and never read it? Either way, please let us know what you think by posting on the BATC forum here


CAT21 Part 2


CAT21 part 2 will be a day of online talks using the very successful format that we used in 2020 which had an audience of nearly 500 ATVers from around the world.

The convention will be available as a Zoom webinar for BATC members enabling live Q+A.

The whole day will also be streamed live on the BATC streamer at https://batc.org.uk/live/cat21 - this does not require registration and all the sessions will be available on the BATC Youtube channel after the event.https://www.youtube.com/c/BATCOnline

The convention program is as follows:

9:30 - Welcome - G8GKQ
9:45 - Portsdown update - G8GKQ
10:45 - Coffee
11:00 - Ryde update - Tim MW0RUD
12:00 - QO100 desktop development - Michael EA7KIR - see viewtopic.php?f=101&t=7551 for background info
12:45 - Lunch - Interactive Q+A session
13:30 - EMF for microwaves and QO100 - Ian GM3SEK and Peter G4SDE - organised jointly with the UKMIcrowave group offering theory and practical advice
15:00 - Coffee
15:15 - DATV Rx system gain distribution - G8GTZ
16:00 - Close

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PA3CRX
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Re: CQ-TV 273 is ready for download

Post by PA3CRX » Fri Oct 15, 2021 7:31 am

In the article about dishes and their feeds (page 14) several designs are mentioned. If you are interested in the mechanical dimensions of the stacked dipoles or the LPA's: please see the pictures below. For pros and cons: read the artickle in CQ-TV :)
23-6cm Stacked dipoles feed.jpg
23-6cm Stacked dipoles feed.jpg (110.72 KiB) Viewed 972 times
LPA design PA0HVA.JPG
LPA design PA0HVA.JPG (174.9 KiB) Viewed 972 times
LPA design 23 13 9 cm DC8CE.JPG
LPA design 23 13 9 cm DC8CE.JPG (149.93 KiB) Viewed 972 times

G8GKQ
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Re: CQ-TV 273 is ready for download

Post by G8GKQ » Fri Oct 15, 2021 8:24 am

Each downloaded CQ-TV is marked with the Member's callsign at the bottom of each page, to discourage the hosting of copies on other websites and to preserve the value of your membership.

Unfortunately, this "watermark" had grown in size (due to other requirements) to obscure some of the text in CQ-TV 273. This has now been corrected.

So, if you want a better-looking copy of CQ-TV, you can now download a second copy with a much smaller watermark.

Apologies for the inconvenience

Dave, G8GKQ

radiogareth
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Re: CQ-TV 273 is ready for download

Post by radiogareth » Fri Oct 15, 2021 8:28 am

Another great issue to enjoy :-) I have a question about the bi-quad design, all the www guidance suggests that distance from the reflector affects VSWR. I've built one for 24cms and whilst clearly 'resonant' at the design frequency, its a horrible match (over 4.0:1) that doesn't change much with reflector distance. Wonder what I'm doing wrong?
Gareth

g4hjw
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Re: CQ-TV 273 is ready for download

Post by g4hjw » Fri Oct 15, 2021 10:04 am

Sweep your test frequency Gareth - i suspect you'll find it's not resonant in band. The better the match, the more sensitive will appear the change in match and you move the antenna towards and away from the dish. That effect is inevitable because of the non linear nature of the return loss figure, being as it is a log value.

Bernie, G4HJW

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PA3CRX
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Re: CQ-TV 273 is ready for download

Post by PA3CRX » Fri Oct 15, 2021 11:30 am

I've built one for 24cms and whilst clearly 'resonant' at the design frequency, its a horrible match
I agree with Bernie. Or something is completely wrong, like crossing in the centre.

With the following design and 3 cm distance to the reflector plate, it should work (23/24 cm band).
Small adjustments could also be made by stretching the square a bit.

bouwtekening doppelquad.gif
bouwtekening doppelquad.gif (5.53 KiB) Viewed 904 times

radiogareth
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Joined: Wed Jan 06, 2016 9:46 am

Re: CQ-TV 273 is ready for download

Post by radiogareth » Fri Oct 15, 2021 11:38 am

I'll start a new thread on this topic....
Thanks
Gareth

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