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OT: application of directional Quad in UHF

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Johnny Siu

OT: application of directional Quad in UHF

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
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RobertG

Re: OT: application of directional Quad in UHF

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:[hidden email]
>
> This list hosted by: http://www.qsl.net Please help support this
> email list: http://www.qsl.net/donate.html Message delivered to
> [hidden email]
>

David Christ

Re: OT: application of directional Quad in UHF

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:[hidden email]
>>
>> This list hosted by: http://www.qsl.net Please help support this
>> email list: http://www.qsl.net/donate.html Message delivered to
>> [hidden email]
>>
>
> --
> Robert G Strickland, PhD ABPH - KE2WY
> [hidden email]
> Syracuse, New York, USA
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

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Ross Primrose

Re: OT: application of directional Quad in UHF

Check out the Quagi: http://n6nb.com/quagi.htm

73, Ross N4RP

--
FCC Section 97.313(a) “At all times, an amateur station must use the minimum transmitter power necessary to carry out the desired communications.”

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Bill Blomgren (kk4qdz)

Re: OT: application of directional Quad in UHF

In reply to this post by RobertG

A friend (who is a mechanic at heart) threw together a 4 element quad for 2 meters, along with a moxon for 2 meter sat work. The feed for the 4 element quad is *straight* coax. To an ugly balun below the antenna.. It feeds at 50 ohm rather nicely. And easy to build. (Spreaders are just fiberglass driveway markers...wire simple 12 gauge wire. It has survived 3 ice storms, and a near miss by a tornado.

Superb directionality and all that. About a 3-4' long piece of pvc for the central beam that holds everything. Portable. And lots of gain.

The moxon gets used with his hand held for sat comm work. In front of the moxon, a 5 or 6 element yagi for 440.

Next experiment for him? I've heard he is working on a quagi. That is a quad reflector, quad driven element.. then a boat load of directors made up of copper wire on a piece of light wood. More gain than a 6 element quad... and lighter.

KK4QDZ - Now with Extra Class Priv's, and a tiny KX3 to enjoy them!

________________________________
From: Robert G Strickland <[hidden email]>
To: [hidden email]
Sent: Friday, April 4, 2014 1:09 PM
Subject: Re: [Elecraft] OT: application of directional Quad in UHF

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/elecraftHelp:
> http://mailman.qth.net/mmfaq.htmPost:
> mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net/Please help support this
> email list: http://www.qsl.net/donate.htmlMessage delivered to
> [hidden email]
>

--
Robert G Strickland, PhD ABPH - KE2WY
[hidden email]
Syracuse, New York, USA

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Message delivered to [hidden email]
______________________________________________________________
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Post: mailto:[hidden email]

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Johnny Siu

OT: application of directional Quad in UHF

In reply to this post by Johnny Siu

Thank you for all your replies to my email below. I have already summerised your input (of course, with credit and copy right to you) and passed to local ham societies for their reference.

This is a great mail listing and I have been benefited from the learnt radio professions.

Thanks a lot.

73

Johnny VR2XMC

________________________________
寄件人︰ Johnny Siu <[hidden email]>
收件人︰ Elecraft <[hidden email]>
傳送日期︰ 2014年04月4日 (週五) 11:05 AM
主題︰ OT: application of directional Quad in UHF

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:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]