At 70 cm element sizes are small enough that self supporting quad elements can be made with number 12 or 14 solid copper wire. Putting a break in such an element is quite simple. Also at that frequency a quad cam be built on a spine which is much easier than what has to be done at HF. Also something we have done here which works quite well at 70 cm is to use a quad driven element and rod type reflector and directors.
David K0LUM On Apr 4, 2014, at 12:09 PM, Robert G Strickland wrote: > Johnny... > I have no experience with UHF quads, but I modeled, used and modified an > HF quad for over 15 years. I now use a SkyHawk HF triband yagi. Based on > that experience, quads require more mechanical effort for construction > and maintenance. The form factor for a yagi is two-dimensional, while for a > quad it is three-dimensional. Thus, packing, storage and transport is > potentially simpler for the yagi than for the quad. Feeding a yagi is simpler > than for a quad, because the yagi can use a solid driven element, while the > quad generally requires a break in the driven element; this can complicate > construction. Adding elements to a yagi antenna is mechanically simpler than > adding elements to a quad. So, based on my HF experience - and thinking about > UHF quads - I think mechanical issues might be a significant difference. At > UHF a 4/5 element yagi might be easier to deal with than a 3-el quad. My > opinion. > > ...robert > > On 4/4/2014 03:05, Johnny Siu wrote: >> Hello Elecrafters, >> >> It is off-topic and you can press 'DEL' now. >> >> Hong Kong is quite a hilly place in the rural areas. Local ham >> societies are often providing radio communication support services to >> charity organisations having fun raising sports activities in these >> areas. We have to set up UHF repeaters at the hill tops. Purely >> from the radio text books, a 3 element quad gives better performance >> than a 3 element yagi. However, I seldom see using directional Quad >> in the UHF repeaters. >> >> Apart from performance, are there any disdvantages (or advantages) of >> using directional quad instead of yagi in UHF repeaters? Could you >> share with me your experience in US? >> >> Thanks for your help in advance and please reply off-the-list to >> reduce the traffic in the mail listing (oh, yes, not forum!!) >> >> 73 >> >> Johnny VR2XMC >> ______________________________________________________________ >> Elecraft mailing list Home: >> http://mailman.qth.net/mailman/listinfo/elecraft Help: >> http://mailman.qth.net/mmfaq.htm Post: >> mailto:[email protected] >> >> This list hosted by: http://www.qsl.net Please help support this >> email list: http://www.qsl.net/donate.html Message delivered to >> [email protected] >> > > -- > Robert G Strickland, PhD ABPH - KE2WY > [email protected] > Syracuse, New York, USA > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
