>
>
>From: "Jim Thomson" <Jim.Thomson@telus.com>
>Subject: RE: [AMPS] Input circuit
To: <amps@contesting.com>
>Date: Fri, 6 Jul 2001 11:59:22 -0600
>
>
>
>
>##### Rick, pse forward this on to whoever.
>
>
>**** For a PI-net, use the excellent spreadsheet on G3SEK's
>website, or the spreadsheet on Rich Measures (AG6K) website. Both
>these fellows post regularly on 'amps' at contesting.com.
>
>
>**** Use a ckt Q of 3-3.5 (This equates to a individual Q of 2
>for the C1 cap. IE: 100ohms/Q-2 =XC of 50 ohms on ALL bands.
>C1 cap will have 50 ohms of Xc on all bands
/\ Most radios havee an output z of 50-ohms. Thus, for a c. Q of 2,
Xc1 =50/2 = 25-ohms. In practice, this will give a Q of a bit over 2.
>
>**** If Q is too low, solid state rigs will not like it.
>Complete info on AG6K's website.
>
>*** There is no commercial source of a ready made tuned input.
>If you are planning to use separate tuned inputs for each band,
>most fellows use small torroids for the coil, and ARCO
>compression trimmers for the C1 + C2 caps. The input Z of a
>4-1000 is aprx 100 ohms. The coils can be tweaked by
>compressing or spreading the turns on each torroid. or tuned
>slugs can be used.
>
>*** avoid using fixed caps, unless you test with air variables
>1st, then measure the value of the variables, and then substitute
>fixed silver mica's. On 160, and maybe 80M, most fellows pad
>the arco's with silver micas.
>
>**** To test ur tuned inputs put a 100 ohm 1/4w carbon
>composition resistor across the output of the pi-net in question,
>and put a MFJ-259/B on the input. Simply tweak both caps for
>flat swr on mfj. repeat for all other tuned inputs.
>
>
>**** Another method is to use two broadcast variables and a tapped
>coil. I use this method on my 3000A7 tube. It's also been
>used on 2 x 4-1000 amps.
>
>**** You can see pix of all this on Larry Molitor's (W7IUV)
>homebrew amp pix page.
>
>*** still another method that is used with 4-1000's is just one
>cap and one coil in parallel, bottom end to chassis, and top
>end facing cathode/exciter. W6RU uses this method often. Pix of
>his amps are also on Molitor's website. Everytime some new pix
>shows up, it's posted on 'amps'.
>
>Cul......Jim VE7RF (ex-VE7RQ)
>
>
>
>
>
>-----Original Message-----
>From: rick rosner [mailto:rar@uniserve.com]
>Sent: Friday, July 06, 2001 10:23
>To: jim.thomson@telus.com
>Subject: Fw: [AMPS] Input circuit
>
>
>
>----- Original Message -----
>From: "Peter" <pb0aiu@pi4cc.nl>
>To: <amps@contesting.com>
>Sent: Friday, July 06, 2001 3:16 AM
>Subject: [AMPS] Input circuit
>
>
>>
>> Hello world,
>>
>> Is there any source for a input circuit for a 4-1000 @ the hf bands? A
>> layout of a print circuit with components is also welcome.
>>
>> Peter
>>
>> Internet DX-cluster telnet://213.10.48.91
>> DX-cluster info http://www.pi4cc.nl/dxcluster
>>
>>
>>
>> --
>> FAQ on WWW: http://www.contesting.com/FAQ/amps
>> Submissions: amps@contesting.com
>> Administrative requests: amps-REQUEST@contesting.com
>> Problems: owner-amps@contesting.com
>>
>
>
- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
end
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