07-08-2017, 09:30 PM
Wayne
A couple of paragraphs need close attention:
The Dual Beam Pro is a non-resonant design requiring an internal/external ATU for 20m to 10m operation. The efficiency/performance is down on 40m when compared to the higher bands and an external ATU may be required.
Coax feeder length is not critical but a recommended length is 25m, check the website for the specification of mini RG8. It is an ideal cable for use with the Dual Beam Pro. The cable will need terminating with a PL259 plugs and this service is offered on the Pro Antennas website.
The above two paras tell most of the story:
non-resonant dipole = high SWR except when approaching dimensions at half wave dipole resonance.
recommended feeder 25 metres = RG58 = lots of distributed loss to reduce effective SWR at the transmitter.
The dimensions...
boom = 5 metres overall = 2.5 metres each side
end elements = 2.5 metres overall = 1.25 m each side of boom
effective half wave dipole dimensions = 2 x 3.75 metres = 7.5 metres
therefore resonant somewhere around 20MHz, lowered a bit due end capacity hat effect.
It should state requiring an internal/external ATU ... for all bands...
The balun ratio is probably somewhere between 4:1 and 16:1 as a best guess.
Hey, it is rotatable but would be relatively inefficient and you could probably do better with something else.
My 2c..
Doug VK4ADC
PS loss on Tx = loss on Rx
A couple of paragraphs need close attention:
The Dual Beam Pro is a non-resonant design requiring an internal/external ATU for 20m to 10m operation. The efficiency/performance is down on 40m when compared to the higher bands and an external ATU may be required.
Coax feeder length is not critical but a recommended length is 25m, check the website for the specification of mini RG8. It is an ideal cable for use with the Dual Beam Pro. The cable will need terminating with a PL259 plugs and this service is offered on the Pro Antennas website.
The above two paras tell most of the story:
non-resonant dipole = high SWR except when approaching dimensions at half wave dipole resonance.
recommended feeder 25 metres = RG58 = lots of distributed loss to reduce effective SWR at the transmitter.
The dimensions...
boom = 5 metres overall = 2.5 metres each side
end elements = 2.5 metres overall = 1.25 m each side of boom
effective half wave dipole dimensions = 2 x 3.75 metres = 7.5 metres
therefore resonant somewhere around 20MHz, lowered a bit due end capacity hat effect.
It should state requiring an internal/external ATU ... for all bands...
The balun ratio is probably somewhere between 4:1 and 16:1 as a best guess.
Hey, it is rotatable but would be relatively inefficient and you could probably do better with something else.
My 2c..
Doug VK4ADC
PS loss on Tx = loss on Rx
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.
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.