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Re: [Amps] resonant choke filters.

To: "Jim Thomson" <Jim.thom@telus.net>, <amps@contesting.com>
Subject: Re: [Amps] resonant choke filters.
From: "Carl" <km1h@jeremy.mv.com>
Date: Sun, 21 Feb 2010 11:13:10 -0500
List-post: <amps@contesting.com">mailto:amps@contesting.com>
I believe Tom settled on 12-15% higher than 120 Hz as the best performing. 
Its somewhere in the archives.

Carl
KM1H


----- Original Message ----- 
From: "Jim Thomson" <Jim.thom@telus.net>
To: <amps@contesting.com>
Sent: Sunday, February 21, 2010 7:07 AM
Subject: [Amps] resonant choke filters.


> Date: Sat, 20 Feb 2010 11:29:34 -0600
> From: "Roy" <royanjoy@ncn.net>
> Subject: Re: [Amps] 120 Hz hum from Henry...
>
>
> "Be careful if you fix this. It's not tuned to *exactly* 120 Hz because 
> that
> would cause a very high voltage to appear across the choke. Use the 
> specified values if
> you replace anything."
>
>
> I strongly believe the above is a perpetuated old hams' tale, totally
> untrue. The parallel-tuned circuit is a frequency-rejection filter,
> exhibiting a very high Z to the 120 Hz ripple, thus preventing high
> circulating current and its resultant voltage build up. Read the article,
> noting the careful tuning to exactly the 120 Hz resonant frequency:
> http://www.qsl.net/i0jx/supply.html
>
> 73,   Roy    K6XK
>
> &&& IF you resonate the filter to exactly 120 hz... the resonating  cap
> WILL  blow up in your face. Try it and you will see for yourself. Been
> there, done that.    Ask Tom Rauch  abt his resonant choke experiences,
> he just abt killed himself.
>
> &&&  also note in the I0JX article.  He uses SIMULATIONS. That`s
> fine, but apparently the simulations  don`t show the exploding cap.
>
> &&  also note he advocates using swinging chokes. Swinging chokes
> are a dead loss, if used in resonant filters. Their inductance is all over 
> the map,
> exactly what you don`t want.  Dahl`s chokes, made for resonating, are very 
> stiff, and
> only drop down in value a small amount, when a huge load is applied.
>
> &&  Look at his plane jane  C input filter.. just ONE 15 uf cap.. 6450 vdc 
> No load,
> and  6175vdc, sucking 1000ma.    6147 divided by 6450 = .957   That`s  a
> 4.3% drop. That`s  superb regulation.   If he had increased the C  to 
> 50-150uf,  you
> will then get a real eye opener. Loaded V is higher.. and on SSB, it won`t 
> droop at all.
>
> In his henry 4 K ultra  example... his No load = 4525vdc.  His loaded V = 
> 3950vdc.
> 3950 divided by 4525 = .873    This is a 13%  DROP !    So much for the 
> nonsense abt
> the infamous Henry radio resonant chokes.They are heavy alright, but they 
> are not heavy duty.
>
> The 8 K ultra used a resonant choke.  It also sucks 300 w of bleeder, just 
> to make the choke,
> look like a choke. ( 5 x 20 k, 100 watt  WW`s in series)  No load is 5400 
> vdc.  To get that,
> they use a 6000 vac xfmr.   If that had been a simple C filer, only a 3800 
> vac  xfmr is needed...
> (and NO choke, nor 300 W  CCS  bleeder)   Loaded V on the 8k = 4800 vdc ,
> 4800 divided by 5400  = .888    again, no fantastic regulation here. 
> (11.1% drop)
>
> IMO, ur better off to dump the resonant choke,and spend the money on the 
> xfmr, and caps,
> not a bunch of excess weight.   Besides, any resonant choke set up will 
> not kill the harmonics
> very well.   The plane jane... BIG C input filter, will kill the 120 hz 
> ripple,,, and ALL the
> harmonix of 120 hz.
>
> later... Jim  VE7RF
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