[Amps] question for you experts...

[Carl]

Im far from waffling Gary if you actually read what I said.
Believe what you want but understanding a bit of the history of its use and 
general acceptance might help temper your comments.


----- Original Message ----- 
From: "Gary Schafer" <garyschafer at comcast.net>
To: "'Carl'" <km1h at jeremy.mv.com>; "'Kathy Bookmiller'" <wb2aio at yahoo.com>; 
<Amps at contesting.com>
Sent: Tuesday, March 27, 2012 10:20 PM
Subject: RE: [Amps] question for you experts...


> Well Carl, which is it? You seem to be waffling both ways.
>
> The only "safety benefit" that the choke offers is it keeps the DC voltage
> at zero on the output terminal of the amplifier so you won't get zapped if
> you should touch the antenna connector or an antenna connected that does 
> not
> have DC continuity in normal operation.
>
> 73
> Gary  K4FMX
>
>> -----Original Message-----
>> From: Carl [mailto:km1h at jeremy.mv.com]
>> Sent: Tuesday, March 27, 2012 9:58 PM
>> To: garyschafer at comcast.net; 'Kathy Bookmiller'; Amps at contesting.com
>> Subject: Re: [Amps] question for you experts...
>>
>> The REAL reason was as I stated since it conformed with Handbook and
>> magazine suggestions for decades prior.
>>
>> The other reason was a secondary benefit found by accident and reported
>> in
>> Hints and Kinks if I remember.
>>
>> Note I also said "theoretical" since the safety benefit is questionable.
>>
>> Maybe Gary can impress us with a test to see which blows open first.
>>
>> Carl
>> KM1H.
>>
>>
>> ----- Original Message -----
>> From: "Gary Schafer" <garyschafer at comcast.net>
>> To: "'Kathy Bookmiller'" <wb2aio at yahoo.com>; <Amps at contesting.com>
>> Sent: Tuesday, March 27, 2012 9:27 PM
>> Subject: Re: [Amps] question for you experts...
>>
>>
>> >A lot of people think that the choke is there as a safety device in
>> case
>> >the
>> > plate blocking capacitor shorts. Most chokes across the output are too
>> > small
>> > in current carrying capacity to be an effective safety device should
>> the
>> > plate blocking capacitor short.
>> >
>> > The real reason for the choke is to keep the output tune capacitor
>> from
>> > charging to some DC level and causing the tune capacitor to arc
>> > constantly.
>> > Most load capacitors are close spaced and only rated for a few hundred
>> > volts. Even if a vacuum capacitor is used as a load capacitor the
>> voltage
>> > rating is often less than the plate voltage supply.
>> >
>> > If there is no DC path to ground on the output of the amplifier then
>> that
>> > puts the plate blocking capacitor in series with the load capacitor
>> and
>> > the
>> > DC plate supply can charge the tune capacitor if there is any slight
>> > leakage
>> > in the plate blocking capacitor.
>> > Another way the load capacitor can charge is from static if an antenna
>> > with
>> > no DC ground across it is connected to the amplifier. This will cause
>> the
>> > load capacitor to continually charge and arc.
>> >
>> > If you hear a constant timed "pop" in your receiver at regular
>> intervals,
>> > maybe a few seconds to several minutes apart, you may have an open
>> choke
>> > on
>> > the output of the amplifier.
>> >
>> > 73
>> > Gary  K4FMX
>> >
>> >> -----Original Message-----
>> >> From: amps-bounces at contesting.com [mailto:amps-
>> bounces at contesting.com]
>> >> On Behalf Of Kathy Bookmiller
>> >> Sent: Tuesday, March 27, 2012 5:11 PM
>> >> To: Amps at contesting.com
>> >> Subject: [Amps] question for you experts...
>> >>
>> >> I was doing some checking out everything on my amp. (NCL2000) and
>> >> noticed that the 2.5mh choke that is after the loading capacitor in
>> the
>> >> amp. was open-connection/wire is gone. Looking at others amps., I see
>> >> they all have them-it would be rfc3 in a SB200, 1.1mh., for example.
>> >> Since they are in all amps, at least tube ones, what is it for? My
>> guess
>> >> it is to short out the HV if the coupling cap. shorted coming from
>> the
>> >> plates, but if I'm right, it doesn't seem heavy enough for a good
>> power
>> >> supply not to just burn it up and keep on putting the HV on the
>> >> antenna/output.
>> >> I think I can save the one in my amp. if I can get the paint off the
>> >> wire by scrapping or chemicals and reconnect it, but by doing this,
>> I'll
>> >> eliminate one of the 4 sections on the choke, but doubt that change
>> in
>> >> value would be a big problem?
>> >> Enlighten this poor QRPer,
>> >> Kathy W2NK
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