Yes. I see that now.
It is so cool to learn from you guys. I learn a lot in this forum!
Sent from my iPad
On 26 jan 2011, at 18:12, "Gary Schafer" <garyschafer@comcast.net> wrote:
> If you look closely at the AL1500 it is pi L only on 160 and 80. The L2 coil
> is completely shorted out on 40 - 10 meters.
>
> With pi L a much smaller output tune capacitor can be used than with just a
> pi network as the impedance at the output of the pi part can be made higher
> than 50 ohms which requires less capacitance to tune.
>
> 73
> Gary K4FMX
>
>> -----Original Message-----
>> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]
>> On Behalf Of Carl
>> Sent: Wednesday, January 26, 2011 11:41 AM
>> To: Ulf (SM0NOR)
>> Cc: amps@contesting.com; Vic K2VCO
>> Subject: Re: [Amps] Pi/L in Ameriton amps?
>>
>> 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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>>
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