[50mhz] Modifying Cushcraft A50-5S

Fri Jun 26 19:38:29 EDT 2009

Yep, 617-6B (aka Boomer in old Cushcraft literature) is what my eyes didnt 
tell my fingers. Hard to believe it was designed in 1979.

Ive blown those gamma matches apart with as little as 400W. The T is so much 
better and efficient but since it costs more its not used on the economy 
antennas.

Carl
KM1H

----- Original Message ----- 
From: "Renée Deeter" <k6fsb.1 at gmail.com>
To: "Carl" <km1h at jeremy.mv.com>; <50mhz at qth.net>
Sent: Friday, June 26, 2009 6:02 PM
Subject: Re: [50mhz] Modifying Cushcraft A50-5S

Carl-
per chance did you mean the Crushcraft 6176B Antenna?
I also have the A50-5S and in need to fix/replace the (internally
shorted- oops! )gamma match.....to something better and a T is almost
always better.
Renée, K6FSB

Carl wrote:
> Correction to the last. With 13.2 dBi translated to 11.05 dBd that antenna
> is right where it belongs on the BQH list. Boom is 1.71 w/l
>
> Carl
> KM1H
>
>
>
> ----- Original Message ----- 
> From: "Carl" <km1h at jeremy.mv.com>
> To: "John Kemker" <john at kemker.org>; "50mhzer's" <50mhz at qth.net>
> Sent: Friday, June 26, 2009 4:38 PM
> Subject: Re: [50mhz] Modifying Cushcraft A50-5S
>
>
>
>> The T match info is right in the Cushcraft 616B Boomer manual. Ive turned
>> that into 8el with 13.2 dBi gain and 40 dB F/R without adding any boom
>> material. Thats my daily driver for almost 20 years.
>>
>> From what I see in the VE7BQH list posted today it has higher gain per
>> boom length than anything listed. According to YO 6.5  its within .2 dB 
>> of
>> theory.
>>
>> Carl
>> KM1H
>>
>>
>> ----- Original Message ----- 
>> From: "John Kemker" <john at kemker.org>
>> To: "50mhzer's" <50mhz at qth.net>
>> Sent: Friday, June 26, 2009 4:05 PM
>> Subject: Re: [50mhz] Modifying Cushcraft A50-5S
>>
>>
>>
>>> I've had a couple of folks send me the W5WVO mods, which I much
>>> appreciate.  That lengthens the boom length with an easy mod and still
>>> uses the gamma match.
>>>
>>> As far as building a T-Match, I don't mind, as long as there's some
>>> decent instructions.  I've got plenty of 75ohm cable and F connectors
>>> and am purchasing some new F female connectors next payday to finish a
>>> 160m RX Loop.  Purchasing a few more for the balun for a T-Match is only
>>> $1 more.
>>>
>>> DX Engineering has the 1.5" X 72" boom addition for the W5WVO design for
>>> under $14.  I'll be ordering that next payday, also.
>>>
>>> Carl wrote:
>>>
>>>> There is only about .1dB to be gained on that boom length. However the
>>>> F/R
>>>> can be much improved from 18 to 28dB if noise is an issue. That boom
>>>> length
>>>> is better for 4 elements at 10 dBi gain and 26 dB F/R if you dont mind 
>>>> a
>>>> DE
>>>> impedance of around 17 Ohms which can easily be stepped up with a T
>>>> Match.
>>>>
>>>> In order to adapt any new design that original gamma match has to go. I
>>>> use
>>>> the all metal T Match in all my designs.
>>>>
>>>> Unfortunately I havent added these designs to a PC file yet but can
>>>> snail
>>>> mail it. This was designed about 12-13 years ago using YO, built and
>>>> verified. However that HD is long since crashed and I cant find the
>>>> floppy
>>>> backups.
>>>>
>>>> Plus I still cant get YO 6.5 functioning on a XP PC with the DOS
>>>> simulators
>>>> Ive tried.
>>>>
>>>> Anybody have YO 7.5 they are willing to share?
>>>>
>>>> Carl
>>>> KM1H
>>>>
>>>>
>>>>
>>>> ----- Original Message ----- 
>>>> From: "John Kemker" <john at kemker.org
>>>>
>>>>> I was wondering if anyone had come up with an improved layout/spacing
>>>>> using the A50-5S as a basis?  I have an A50-5S, but feel that there
>>>>> should be some way to improve the performance with a few
>>>>> modifications/changes.  Anyone have any suggestions?  I can lengthen
>>>>> the
>>>>> boom, change the lengths and spacing of the elements, etc.  I'm not
>>>>> going to be able to do much in the way of modifying the gamma match, 
>>>>> or
>>>>>
>>>>>
>>>>> adding extra elements.
>>>>>
>>>>>
>>> -- 
>>> --JohnK
>>> 73 de W5NNH
>>> 10X 75371/M&M 117/SMIRK 6185/Six Club 285/TRA 2499/Norcross 228 F&AM
>>>
>>>
>>>
>>>
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>>>
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