Posts: 43
Threads: 10
Joined: Sep 2016
Greetings
I am gathering ideas for a future project, a homebrew 160 metre transmitter.
The thought process is -
Transmitter only (rx not required)
About 20 watts or more carrier
AM only
Xtal or VFO controlled
Solid state but a valve circuit is not out of the question.
Drew Diamond has published some excellent articles in this field, but I would like to cast the ideas net wider.
So, what do I need help with? Your ideas are most welcome. For example what are you using on 160 m? Is the circuit in a magazine, book or some other place?
As mentioned at the top of the post, I am looking for ideas on what you have homebrewed.
73
Ron
VK4BVI
Posts: 153
Threads: 16
Joined: Feb 2017
Have you listened?
160m is a nighttime band.
Almost every morning, activity on 1859 KHz at 5AM between about five stations.
John VK1CJ, Tom VK2TB Rydal or Batemens Bay, VK8RC port 4 Deception Bay to name a few.
They are all using full size 160m dipoles or equivalent large antenna.
Power wise, either 100W transceivers or 400W amplifiers.
Power AND a full sized antenna is everything. (and SSB!)
Listening is easy. here, my TV pole guy wires, each 7m.
Alan VK2ZIW
Posts: 1,291
Threads: 326
Joined: Sep 2016
Ron
Your post made me start thinking.. and do a little researching. I don't have access to the Drew Diamond articles so can't comment on that approach.
While a little old now, the FAT5 project makes for interesting reading :
http://www.shortwaveradio.co.uk/fat5_may2010.htm
Even more interesting was the article on the PWM-mode modulator to achieve AM.
http://www.shortwaveradio.co.uk/puwma%20draft4.pdf
There are probably other sources in lieu of VFO or crystal stabilisation, eg a DDS module from VK5TM :
https://www.ahrdf.net/forum/thread-646-p...ml#pid2658 and
http://www.vk5tm.com/homebrew/dds_vfo_8/dds_8.php
A thought did cross my mind about this project though : if you could find an old HF marine transceiver that worked down on 2MHz, that could supply you with most of the parts you would need to re-homebrew with. The tuning capacitors etc, maybe the output LPF parts, modulation arrangements, etc.., all might be suitable particularly if you used an old-technology approach.
I have to admit to not having homebrewed a HF transmitter in years and then it was a single-band 20M SSB transceiving device using 4 x FT243 style crystals in a homebrew crystal filter at around 5MHz, another as the carrier injection crystal. I don't have the whole device left but I did retain the crystal filter - it's in the parts junkbox. I have certainly done VHF / UHF / microwave homebrewing and even test gear for HF, but no straight transmitters. I don't have any plans for 600M and 2200M gear either so no homebrewing for there either.
Doug VK4ADC @ QG62LG51
http://www.vk4adc.com
This Forum is only going to be as interesting as the posts it contains.
If you have a comment or question, post it as it may trigger or answer the query in someone else's mind.
Posts: 43
Threads: 10
Joined: Sep 2016
Listening around there is some activity in SE Queensland, and AM as well, probably not as much as Melbourne.
Doug, the links are interesting reading, and will be noted in the lead up to the project. The FAT 5 is 50 watts, which still within the project scope.
I have had a quick read on shunt feeding a tower, which has piqued my interest, as you remember previously living in suburbia, full wave or even half wave antennas on 160m are pushing the boundary at times.
Anyway time to hit the books and internet for more research.
Cheers
Ron
Posts: 27
Threads: 2
Joined: Mar 2018
Get to know your neighbours. Have a coffee with them and talk to them what you'd like to do. A Half wave dipole is quite possible in suburbia, depending on your situation. You'll be better off with an off centre fed dipole at 160m if you want a reasonably high impedance feed. There is a net in SE Queensland on Monday nights. I sometimes check into that if there are not too many QRP stations.
At least the thunderstorms should start to diminish as we head into winter.
