13-09-2019, 07:28 AM
Igor
That may not be a fair way of testing them. They are a mobile antenna so will normally operate with a ground plane and sitting them atop an antenna analyser will not provide the same earth plane effect. It will certainly screw up any feed impedance measurements.
Screw them onto a mobile base properly mounted on a vehicle and re-measure at about the same frequencies - as well as sweeping to find out what the SWR minima frequencies are. Post those results too so we can compare for ourselves. Numeric format is fine, rather than the series of photos...
Adjusting the radiator lengths telescoping into the holes (i.e. by releasing the grubscrews) move the results much ?
{ base grubscrews mainly for 70cm, ones above the loading coil more for 2M, but both interact }
Doug
That may not be a fair way of testing them. They are a mobile antenna so will normally operate with a ground plane and sitting them atop an antenna analyser will not provide the same earth plane effect. It will certainly screw up any feed impedance measurements.
Screw them onto a mobile base properly mounted on a vehicle and re-measure at about the same frequencies - as well as sweeping to find out what the SWR minima frequencies are. Post those results too so we can compare for ourselves. Numeric format is fine, rather than the series of photos...
Adjusting the radiator lengths telescoping into the holes (i.e. by releasing the grubscrews) move the results much ?
{ base grubscrews mainly for 70cm, ones above the loading coil more for 2M, but both interact }
Doug
Doug VK4ADC @ QG62LG51
http://www.vk4adc.com
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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.