Hi Chris and others..move almost happening, advice required please.
moving very soon we hope ( on going for 6 months!!!!) to Bittaford, Devon from Dagenham, London.. big changes bigger garden!
antennas here for low bands are mag loops..work well considering 5 by 8m garden..
new place is 200 m odd above sea level, line of sight to sea ( sw, can see the sea) and same to w and almost nw, but obviously can’t see the sea as too far. But nothing in way..
garden is 30m long by 17 wide..Does have 11kv overhead running down left hand side..bummer..but still plenty of room to fit low band marconi T on right.
garden slopes down at 3-4:1, steep, but over valley, so real good take off i hope. Plus 11kv is then 15m above garden.
taking the mag loops with me, but I know I can do better with a loaded T ..(160-80, maybe 40.) hf for now will be a cobweb on house..( discretion needed as in Dartmore national park. Ie no towers!!)
So a few questions if you don’t mind..see below.
the garden is a jungle..first thing i will be doing is totally clearing it..a blank antenna farm canvas..
Chris, you mentioned in various posts you have used Logs..
I intend to erect the LZ1AQ directional array I have ( ises 3 parallel crossed loops in a triangle and switched phasing unit to give 4 directions.) Plus try a log..
re log.. WILL it work over radials from the Marconi T? They won’t be “ touching but a few cm’s under it..log will be in area marked PATIO.
tx antenna for low bands will be T with vertical section 10m ( if possible).T will be 30m.
yes it will be loaded for 160m, maybe not so for 80. From T will hang a 40m vertical.
below T will be as much copper as can roll out..I have 1000m of wire ready for..
so Chris.. using your isolation transformer design with loop radials.
the rsgb article is a little vague..the dia shows one end of loop to transform counterpoise connection, the other end to gnd, but description says both ends of loop to counterpoise connection.. Which is it please?
have you had any feedback from your experience on loop radials vs traditional radials work better on tx as well as rx??
Can you give any guidance as to if log is ok over radials ( vertical WILL be disconnected on rx via vac relay. Also needed to stop interaction with rx loops.)as a mater of info I may well swap out LZ1AQ loops for cardiod loops and phase them using the LZ1AQ delay box..might be interesting to try,
I enclose some pics to show you what working with re garden.
thanks for reading Simon g0zen
pics showing garden..steep!!
re core material. Ferroxcube dont list core material you have in rsgb article..4c65 yes??? No 4a11
I'll reply to your email over the weekend.
The 4A11 core material has a ui of 800 where the 4C65 material is 125.
4A11 would be suitable for 160/80m but 4C65 is better for the higher HF bands.
All stocks of Ferroxcube toroids were cleared out during the Covid lockdown. Their plant in Poland was closed down for most of the lockdown and it will take years to build stocks of every material and core size up again.
There is also small demand for good low loss ferrite for RF transformers as the biggest market these days is for lossy ferrite for common mode chokes.
At least it helps keep the RF noise levels down!
I look forward to hearing from you.
Ps so what other cores will work? 73??
Due to the extra loss it extends it's use as a common mode choke down to 1.5 MHz but is is not recommended for use as a transformer due to the high loss.
For transformer use at 1.8 MHz 43 material is useable at medium power levels but the core will heat up at high power levels.
61 material is probably the best option for a RF transformer at HF due to it's low loss but you will need to have extra turns on the transformer to extend the frequency range down to 1.8 MHz.
Thanks for replying
Do you have any recommendations for how many extra windings on type 61 or is that for me to experiment with?
The fcp isolation transformer..it uses type 2..similar in principle, total isolation..will it work?
Thanks for help.
Ps new twin loop looks excellent, very well built and a good price for what you get! Hope it sells well as it should! I assume when used horizontally the usual rule applies, higher the better. (For low angle takeoff.) plus pole, if used horizontally, non metallic?
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