[TowerTalk] TowerTalk Digest, Vol 97, Issue 2

Sun Jan 2 11:41:37 PST 2011

I have a 15 yr. old  A4S w/40mtr add on. Here is the link to the manual:

http://www.cushcraftamateur.com/pdffiles/A4S.pdf

Bud
W1NSK

On 1/2/2011 10:29 AM, towertalk-request at contesting.com wrote:
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> Today's Topics:
>
>     1. 1/4w matching, Common mode chokes and BAL-UN (Jim Thomson)
>     2. 1980s Cushcraft A4 (mikflathead at aol.com)
>     3. RG 303 (dave arruzza)
>     4. Re: 1980s Cushcraft A4 (Jim W7RY)
>     5. Re: RG 303 (Rik van Riel)
>     6. Re: RG 303 (Pete Smith)
>     7. Re: Recommended Coaxial Surge Protector for HF (Rick Stealey)
>     8. Re: 1980s Cushcraft A4 (Jack Brindle)
>     9. Re: 1980s Cushcraft A4 (Al Williams)
>    10. Re: 1980s Cushcraft A4 (W7RIS)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sun, 2 Jan 2011 02:46:56 -0800
> From: "Jim Thomson"<jim.thom at telus.net>
> Subject: [TowerTalk] 1/4w matching, Common mode chokes and BAL-UN
> To:<towertalk at contesting.com>
> Message-ID:<5C5A80A600EA46D389E3D49F9AA1AF35 at JimboPC>
> Content-Type: text/plain;	charset="iso-8859-1"
>
> Date: Fri, 31 Dec 2010 20:05:57 +0000
> From: Steve Hunt<steve at karinya.net>
> Subject: Re: [TowerTalk] 1/4w matching, Common mode chokes and BAL-UN
>
> I have some modeled examples on my web site which illustrate the effect
> Jim [K9YC] is talking about. Take a look at the section "Why reactive chokes
> are undesirable" on this page:
> http://www.karinya.net/g3txq/chokes/
>
> The section finishes: "We conclude that a high value Resistive choke is
> the safe option for all scenarios. We also conclude that Rules-of-Thumb
> which equate the required choke impedance to some multiple of the
> differential-mode load impedance are unsound."
>
> 73,
> Steve G3TXQ
>
> ##  excellent info. My conclusion is... for a monoband yagi set up, use a 1/4  or
> 3/4 wave of coax  from DE  to tower... IF possible.. or close to it.  Grnd braid
> at top of tower or on mast.  Or grnd braid  via the remote switch box, if remote switch
> box located at top of  tower, or on mast.  OK, then use a balun at the DE....that is  mostly resistive.
> IF the balun is mostly resistive, the combo of a phys 1/4 wave  coax [x .98]  + resistive balun
> = excellent combo.  I can pull that off on 20-17-15m.  Can't be done on 80-40m. Since my
> remote switch box is 1/2 way up the mast, a line isolator will be located at the Input of the remote
> switch box.  The line isolator is just 393 wrapped around some type 31 cores...with connector's
> on both ends.  It's job is to ...'clean up'  any residual CM currents, b4 the single coax heads down the
> tower.  Braid of single coax is  bonded to  base of tower /gnd sytem  via lightning arrestor.
>
> ## Coax then routed 75'  along the grnd to just inside of  basement..and terminates on a 2nd
> lightning arrestor..which is bolted to the SPG [large sheet of 1/4" thick AL plate].  More coax to LP
> filter [also bolted to SPG plate], then more coax to a 2nd line isolator.... then more coax to
> wattmeter coupler/amp etc. Both line isolators are inside plastic nema box's, with type 31 cores
> suspended in mid air inside  the nema  box. [to minimize stray C] .   If all that doesn't do it... I give up.
>
> later... Jim  VE7RF
>
>
> ------------------------------
>
> Message: 2
> Date: Sat, 01 Jan 2011 15:22:37 -0500
> From: mikflathead at aol.com
> Subject: [TowerTalk] 1980s Cushcraft A4
> To: towertalk at contesting.com
> Message-ID:<8CD7808C3DEB53B-FBC-21ADC at webmail-d033.sysops.aol.com>
> Content-Type: text/plain; charset="us-ascii"
>
>
>
>
>   I acquired a late 70 A4 off a friend late dad. The center of the driven element is a black insulated material about 2 inches in diameter that the U bolts mount to the boom. There are two 1/4 20 tapped holes that I assume were to mount the feed line. As you might have determined I do not have the instruction manual. Can I use two brass bolts to connect the feed line to? How are they making connection to the tubing? It evidently worked as this was up for almost 30 years. Thanks Mike
>
>
>
>
> ------------------------------
>
> Message: 3
> Date: Sat, 1 Jan 2011 19:38:27 -0800 (PST)
> From: dave arruzza<w1ctn at yahoo.com>
> Subject: [TowerTalk] RG 303
> To: towertalk at contesting.com
> Message-ID:<980402.78546.qm at web38208.mail.mud.yahoo.com>
> Content-Type: text/plain; charset=us-ascii
>
> To all:
> I have been searching the internet for suppliers of RG303 coaxial.
> I am building a few choke baluns for my station.
>
> Does anyone have a small volume supplier of this cable? I don't need a 1000 foot spool for the number of baluns I am building.
>
> 73 es TIA
> Happy New Year
> Dave
> W1CTN
> Radio Ansonia
>
>
>
>
>
>
> ------------------------------
>
> Message: 4
> Date: Sun, 2 Jan 2011 07:16:50 -0800
> From: "Jim W7RY"<w7ry at inbox.com>
> Subject: Re: [TowerTalk] 1980s Cushcraft A4
> To:<towertalk at contesting.com>,	<mikflathead at aol.com>
> Message-ID:<3CDCB6DF0C524129885A6AF9CADAA898 at Laptop>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> 	reply-type=original
>
>
> Most likely an ATB-34. Should be a manual on line.
> 73
> Jim W7RY
>
>
> --------------------------------------------------
> From:<mikflathead at aol.com>
> Sent: Saturday, January 01, 2011 12:22 PM
> To:<towertalk at contesting.com>
> Subject: [TowerTalk] 1980s Cushcraft A4
>
>>
>>
>> I acquired a late 70 A4 off a friend late dad. The center of the driven
>> element is a black insulated material about 2 inches in diameter that the
>> U bolts mount to the boom. There are two 1/4 20 tapped holes that I assume
>> were to mount the feed line. As you might have determined I do not have
>> the instruction manual. Can I use two brass bolts to connect the feed line
>> to? How are they making connection to the tubing? It evidently worked as
>> this was up for almost 30 years. Thanks Mike
>>
>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk at contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
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>>
>>
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>
> ------------------------------
>
> Message: 5
> Date: Sun, 02 Jan 2011 10:49:42 -0500
> From: Rik van Riel<riel at surriel.com>
> Subject: Re: [TowerTalk] RG 303
> To: towertalk at contesting.com
> Message-ID:<4D209E96.9070809 at surriel.com>
> Content-Type: text/plain; charset=UTF-8; format=flowed
>
> On 01/01/2011 10:38 PM, dave arruzza wrote:
>> To all:
>> I have been searching the internet for suppliers of RG303 coaxial.
>> I am building a few choke baluns for my station.
>>
>> Does anyone have a small volume supplier of this cable? I don't need a 1000 foot spool for the number of baluns I am building.
> Small volumes of RG303 seem to be exorbitantly expensive,
> with several shops charging several dollars per foot.
>
> I did find one seller with 75 cents/foot:
>
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120666066468
>