[VHFcontesting] Tech Help needed

WM3M wm3m73 at gmail.com
Sun Jan 3 13:30:47 EST 2021


Interesting discussion, I have Cushcraft 6 meter, 3 element, adjusted it 
many times, best I can get at 50.125 is 2.2:1, considering taking it 
down and trying something else.

Emory  WM3M

On 1/3/2021 1:19 PM, k3sk at hiddenacresfarm.com wrote:
> I'd be a little more interested in what was done to resonate the Cushcraft
> yagi.   I have the newer 6 element version and using the "factory
> recommended "  settings my resonate point with the best SWR is just above 52
> MHz.   I'm currently using a tuner and have been able to live with it, but
> I'd like to get SWR reasonable at 50.100 to 50.313 where it is currently
> 2.5:1.
>
> de K3SK
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sun, 3 Jan 2021 04:58:18 +0000 (UTC)
> From: nosigma at aol.com
> To: chetsubaccount at snet.net, vhfcontesting at contesting.com
> Subject: Re: [VHFcontesting] Tech Help needed
> Message-ID: <1663620010.6568776.1609649898988 at mail.yahoo.com>
> Content-Type: text/plain; charset=UTF-8
>
>
> Interesting thread.? I face a similar band width problem but fortunately
> conquered it with a lot of help.
>
>   I need to run SSB, FT8 at the low end (50.125-50.313) and FM (52.525) at
> the high end.? With the Gamma match Cushcraft (go ahead, hate on me for
> using it) 5 element I was able to get well under 1.5:1 except from 51.100 to
> 51.800.? It was a full days work with a blue tooth wireless head on a
> spectrum analyzer that let us test with the mast up and down (fold over on
> Jeep).
>
> The Gamma match settings are way off the mfg spec to make it work.? The
> critical tuning was to the reflector and first two directors.? The reflector
> is marginally asymmetric (probably due to 45 deg polarization with mast
> interference) and much wider than the SSB spec with the first two directors
> being a bit narrower than the SSB spec.? FM to 400mi and SSB (running W4IY
> KW amps & heliax) going from Va to? Europe and the Pacific Northwest.?
> 4000ft elevation didnt hurt.
>
> The ability to slide the reflector? and directors in and out to change width
> was the enabling capability of the antenna that allowed the silly wide
> bandwidth to be achieved.?
>
> I know the M2's are fixed width elements, but if you the time to experiment
> playing with sleeves of tubing on the reflector and first couple directors
> you might get good results.
>
> 73
> John
> KM4KMU
> On Saturday, January 2, 2021 chetsubaccount <chetsubaccount at snet.net> wrote:
> This brings up again the age old question: do I want to DX or contest?
>
> A high gain, narrow band antenna does not send a CQ in a wide azimuth. But
> today's rules allow you to call someone on your cellphone and ask them to
> get on and give you their grid while you beam there way.
>
> Vs.
>
> Less elements on the yagi (but you can stack them? for more gain or have
> multiple yagis) and call CQs that may be heard over a wider coverage
> azimuth.
>
> Kind of like fishing- try by yourself to read the areas to fish vs. other
> boats telling you where to go. Either way you will catch fish and have fun.
>
> Your station, your choice!
>
> Hoping to catch many fish this January.
>
> 73,
> Chet, N8RA
>
>
>
> -----Original Message-----
> From: VHFcontesting
> <vhfcontesting-bounces+chetsubaccount=snet.net at contesting.com> On Behalf Of
> Dan Evans via VHFcontesting
> Sent: Saturday, January 2, 2021 7:59 PM
> To: 'Jim Worsham' <wa4kxy at bellsouth.net>; Paul Rollinson
> <Paulrollinson at sbcglobal.net>
> Cc: 'VHF Contesting Reflector' <vhfcontesting at contesting.com>
> Subject: Re: [VHFcontesting] Tech Help needed
>
> Hi Paul,No help here with the issue, but I wanted to thank you and the list
> for the topic.
> I currently have a CC 6 element on a small tower.? I have a bigger tower I
> hope to put up soon, and I've been wanting to upgrade to the 6M7 if I ever
> get the tower project off the ground.? So I will likely face the same
> issues.
> I've been following with interest.
> 73Dan
> -- K9ZF? President, Clark County Amateur Radio Club,Amateur Radio Emergency
> Service, Clark County Indiana. EM78el The once and future K9ZF /R no budget
> Rover? ***QRP-l #1269 Check out the Rover Resource Page at:? List
> Administrator for: InHam+grid-loc+ham-books? Ask me how to join the Indiana
> Ham Mailing list!
>
> ? ? On Saturday, January 2, 2021, 11:55:03 AM EST, Paul Rollinson
> <paulrollinson at sbcglobal.net> wrote:?
>   
>   Good morning all,
>
> It appears that I'm not alone with this issue. It's a great antenna until
> you try to push up the band for the digital modes, with potential for more
> to come.
>
> So far I've learned this from this list and other friends in the VHF
> spectrum:
>
> The theory behind moving the shorting bars out to more the freq up the band
> may be based on simple J pole type design, when you short higher up the
> driven element, it increases in resonate freq.
> The 70 ohm (RG-6) phasing line might be able to raise the center freq if
> shortened. If anyone has done this, please reply with length to attempt.
> The driven element might be able to be sleeved increasing the diameter and
> potential bandwidth, which is the biggest problem with this design.
> Electrically lengthening the T match bars using? retaining rings at the end
> may create an aching point at hi power and wet environment. This may be
> catastrophic for an amp and will not be explored.
> Repositioning D1 may help but this has unknown effect of performance.
> Finding a better, free space test range will be first on the list. I have
> 90Ft trees here so spanning 2 trees and hanging the antenna in the middle
> show be effective.
> I still plan on calling M2 on Monday to see if I'm missing something
>
> I will say this, great responses from the VHF community. Thanks to all.
>
> 73,
>
> Paul Rollinson, KE1LI
> Rollinson Associates
> 860-928-5147
> 860-208-8814 Cell/Text
> Paulrollinson at sbcglobal.net
>
> Representing Component Part
> Manufacturers for over 35 years
>
> info/vhfcontesting
> ?
> _______________________________________________
> VHFcontesting mailing list
> VHFcontesting at contesting.com
> http://lists.contesting.com/mailman/listinfo/vhfcontesting
>
> _______________________________________________
> VHFcontesting mailing list
> VHFcontesting at contesting.com
> http://lists.contesting.com/mailman/listinfo/vhfcontesting
>
>
> ------------------------------
>
> Message: 2
> Date: Sun, 3 Jan 2021 12:35:02 +0000 (UTC)
> From: mikflathead at aol.com
> To: "wa4kxy at bellsouth.net" <wa4kxy at bellsouth.net>,
> 	"chetsubaccount at snet.net" <chetsubaccount at snet.net>
> Cc: "VHFcontesting at contesting.com" <VHFcontesting at contesting.com>
> Subject: Re: [VHFcontesting] Tech Help needed
> Message-ID: <1762347524.5016996.1609677302387 at mail.yahoo.com>
> Content-Type: text/plain; charset=UTF-8
>
> Why was a frequency so far from 50.125 chosen for FT8? Mike
>
>
> -----Original Message-----
> From: Jim Worsham <wa4kxy at bellsouth.net>
> To: chetsubaccount at snet.net
> Cc: VHFcontesting at contesting.com
> Sent: Sat, Jan 2, 2021 10:45 pm
> Subject: Re: [VHFcontesting] Tech Help needed
>
> That is my thinking also. You can have a single really large antenna with a
> narrow beam width or stack two (or more) smaller antennas.
>
> 73
> Jim, W4KXY
>
> Sent from my iPad
>
>> On Jan 2, 2021, at 8:46 PM, chetsubaccount at snet.net wrote:
>>
>> ?This brings up again the age old question: do I want to DX or contest?
>>
>> A high gain, narrow band antenna does not send a CQ in a wide azimuth. But
> today's rules allow you to call someone on your cellphone and ask them to
> get on and give you their grid while you beam there way.
>> Vs.
>>
>> Less elements on the yagi (but you can stack them? for more gain or have
> multiple yagis) and call CQs that may be heard over a wider coverage
> azimuth.
>> Kind of like fishing- try by yourself to read the areas to fish vs. other
> boats telling you where to go. Either way you will catch fish and have fun.
>> Your station, your choice!
>>
>> Hoping to catch many fish this January.
>>
>> 73,
>> Chet, N8RA
>>
>>
>>
>> -----Original Message-----
>> From: VHFcontesting
>> <vhfcontesting-bounces+chetsubaccount=snet.net at contesting.com> On
>> Behalf Of Dan Evans via VHFcontesting
>> Sent: Saturday, January 2, 2021 7:59 PM
>> To: 'Jim Worsham' <wa4kxy at bellsouth.net>; Paul Rollinson
>> <Paulrollinson at sbcglobal.net>
>> Cc: 'VHF Contesting Reflector' <vhfcontesting at contesting.com>
>> Subject: Re: [VHFcontesting] Tech Help needed
>>
>> Hi Paul,No help here with the issue, but I wanted to thank you and the
> list for the topic.
>> I currently have a CC 6 element on a small tower.? I have a bigger tower I
> hope to put up soon, and I've been wanting to upgrade to the 6M7 if I ever
> get the tower project off the ground.? So I will likely face the same
> issues.
>> I've been following with interest.
>> 73Dan
>> -- K9ZF? President, Clark County Amateur Radio Club,Amateur Radio
> Emergency Service, Clark County Indiana. EM78el The once and future K9ZF /R
> no budget Rover? ***QRP-l #1269 Check out the Rover Resource Page at:? List
> Administrator for: InHam+grid-loc+ham-books? Ask me how to join the Indiana
> Ham Mailing list!
>> ? ? On Saturday, January 2, 2021, 11:55:03 AM EST, Paul Rollinson
> <paulrollinson at sbcglobal.net> wrote:?
>> Good morning all,
>>
>> It appears that I'm not alone with this issue. It's a great antenna until
> you try to push up the band for the digital modes, with potential for more
> to come.
>> So far I've learned this from this list and other friends in the VHF
> spectrum:
>> The theory behind moving the shorting bars out to more the freq up the
> band may be based on simple J pole type design, when you short higher up the
> driven element, it increases in resonate freq.
>> The 70 ohm (RG-6) phasing line might be able to raise the center freq if
> shortened. If anyone has done this, please reply with length to attempt.
>> The driven element might be able to be sleeved increasing the diameter and
> potential bandwidth, which is the biggest problem with this design.
>> Electrically lengthening the T match bars using? retaining rings at the
> end may create an aching point at hi power and wet environment. This may be
> catastrophic for an amp and will not be explored.
>> Repositioning D1 may help but this has unknown effect of performance.
>> Finding a better, free space test range will be first on the list. I have
> 90Ft trees here so spanning 2 trees and hanging the antenna in the middle
> show be effective.
>> I still plan on calling M2 on Monday to see if I'm missing something
>>
>> I will say this, great responses from the VHF community. Thanks to all.
>>
>> 73,
>>
>> Paul Rollinson, KE1LI
>> Rollinson Associates
>> 860-928-5147
>> 860-208-8814 Cell/Text
>> Paulrollinson at sbcglobal.net
>>
>> Representing Component Part
>> Manufacturers for over 35 years
>>
>> info/vhfcontesting
>>
>> _______________________________________________
>> VHFcontesting mailing list
>> VHFcontesting at contesting.com
>> http://lists.contesting.com/mailman/listinfo/vhfcontesting
>>
>> _______________________________________________
>> VHFcontesting mailing list
>> VHFcontesting at contesting.com
>> http://lists.contesting.com/mailman/listinfo/vhfcontesting
> _______________________________________________
> VHFcontesting mailing list
> VHFcontesting at contesting.com
> http://lists.contesting.com/mailman/listinfo/vhfcontesting
>
>
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>
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>
> ------------------------------
>
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