The designers choice
Carl
KM1H
----- Original Message -----
From: "Ulf (SM0NOR)" <ulf@sm0nor.com>
To: "Carl" <km1h@jeremy.mv.com>
Cc: "Vic K2VCO" <vic@rakefet.com>; <amps@contesting.com>
Sent: Wednesday, January 26, 2011 11:32 AM
Subject: Re: [Amps] Pi/L in Ameriton amps?
So, if I interpret this correctly the lower Q of L2 makes the tank less
sensitive to a wider frequency change? The conclusion of that would thus be
that it is not necessary to tap L2 for each band? How come most amplifiers
do that then?
73's
Ulf (SM0NOR)
ulf@sm0nor.com
On 26 jan 2011, at 16.28, Carl wrote:
> It allows a lower tank Q so there is less retuning needed and the L takes
> care of the higher harmonic content. Ameritron has been doing that since
> their beginning.
>
> Carl
> KM1H
>
>
> ----- Original Message -----
> From: "Vic K2VCO" <vic@rakefet.com>
> To: <amps@contesting.com>
> Sent: Wednesday, January 26, 2011 10:06 AM
> Subject: Re: [Amps] Pi/L in Ameriton amps?
>
>
>> It's common to use a pi-L only on the lower bands and a simple pi on the
>> higher ones. This
>> may be in order to use a smaller-sized output capacitor. Or perhaps
>> additional harmonic
>> suppression is necessary on the lower bands to meet FCC (etc.)
>> regulations.
>>
>> On 1/26/2011 4:35 AM, Ulf (SM0NOR) wrote:
>>> Yes, you are right.... I was confused because I thought it said "pi-l"
>>> in the specs
>>> sheet. But it doesn't.
>>>
>>> Still my question applies to the bigger amplifiers. For example the
>>> specifications of
>>> AL-1500 says "pi-l" but if you check the schematics, the third coil,
>>> after C2, called
>>> L4 is only tapped once!
>>>
>>>
>>> 73's
>>>
>>> Ulf (SM0NOR) ulf@sm0nor.com
>>>
>>>
>>>
>>> On 26 jan 2011, at 13.16, Dave M wrote:
>>>
>>>>
>>>> I hate the layout of the supplied schematic , but it is a standard Pi
>>>> network not PiL
>>>> the second coil is strictly for the higher freqs
>>>>
>>>>
>>>> ......................................................................................................
>>>>
>>>>
>>>>
>> 73 VE3DV , Dave
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>> From: ulf@sm0nor.com Date: Wed, 26 Jan 2011 13:04:07 +0100 To:
>>>>> amps@contesting.com
>>>>> Subject: [Amps] Pi/L in Ameriton amps?
>>>>>
>>>>> I'm helping a friend of mine who bought a damaged 811H. Transformer
>>>>> and
>>>>> tubes where
>>>>> gone. New transformer is on the way from Ameritron and tubes we found
>>>>> locally. I
>>>>> think we will have it up and running on no time! Now my question: is
>>>>> it
>>>>> a pi/l tank
>>>>> in this amp? The manual says so but the second coil has only two
>>>>> tappings. Does it
>>>>> mean that the high bands goes through the same inductance and the low
>>>>> bands go
>>>>> through the whole coil? What does it do for the intermediate
>>>>> resistance? I noticed
>>>>> all Ameritron amps are the same.
>>
>>
>> --
>> Vic, K2VCO
>> Fresno CA
>> http://www.qsl.net/k2vco/
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>
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