[Amps] 10 KW CCS ON 6M...USING THE 3CX-6000A7... PART 12

[Alek Petkovic]

Good onya Jim. Thanks for that.

It's coming along nicely. It'll be fun to see it producing the predicted 
goods. I've got wood already.

73, Alek.

On 2/12/2022 1:46 am, jim.thom jim.thom at telus.net wrote:
> Date: Thu, 1 Dec 2022 07:58:49 +0800
> From: Alek Petkovic <vk6apk at bigpond.com>
> To: amps at contesting.com
> Subject: Re: [Amps] 10 KW CCS ON 6M...USING THE 3CX-6000A7... PART 12
>
> <Yes, me too but I just can't get my head around that piece of bent
> <copper strip being sufficient inductance for 6m.
>
> <I have a bigger coil in my 2m amp and my 6m amp has quite a few turns.
>
> <73 and thanks, Alek, VK6APK.
>
> ## The tube is run at 5.5 kv @ 3amps under load.  Plate load Z = 1019 ohms.
> With a conventional PI network, the MINIMUM Q we can use is a whopping 24.
> That results in an insane  79 amps of RF flowing through the conventional
> tank coil. (all based on 51 mhz)
>
> If a conventional  PI network is used,  (Q = 24)  software spits out:  (51
> mhz)
> C1  =  13.1 pf
> L =  .20 uh
> C2 = 266 pf
>
> Ok, now we switch to the "L-PI' network  (Q = 11)    (51 mhz)  Plate load Z
> is now transformed down to just  192 ohms. The anode to grid C + strays  +
> the .13 uh 1st coil forms a step down L network.
>
> 1st coil  (between plate block caps and C1 main vac tune cap)  = .13 uh
> C1 = 17.7 pf
> L =   .12 uh
> C2  =   227.6 pf.
>
> I used a high tech version of Termans formula for strap length for required
> inductance. And yes, those straps are the correct length for the required
> inductance. The measured results are dead on with his formulae for
> straps..IE:  'flat wire'.
> https://chemandy.com/calculators/flat-wire-inductor-calculator.htm  (Here
> is the mating round wire software.
> https://chemandy.com/calculators/round-wire-inductance-calculator.htm)
>
> The big advantage of the straps is... they have 2 x sides, which doubles
> the RF current capacity.  IF the straps were wound into coils, the current
> capacity is only 1/2...so  2" wide strap coils would have to be used.....
> instead of the 1" wide arced straps we used.
> If tubing coils were used, the tubing would have to be 1.27" in diameter.
> The closest readily available copper tubing is 1.125" OD..and comes in 50'
> rolls...and is an absolute bitch to wind.
>
> In the next video, a temp 1019 ohm resistor will be wired from anode to
> chassis..and analyzer on the output. Then caps tweaked for 1:1 swr  @ 51
> mhz.  Then leave the tune + load caps alone, then sweep from 50-52
> mhz...and then again, but wider extremes, till we find the 2:1  swr points.
>
> Jim  VE7RF
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