[hpsdr] QSO on 3 at 400 mW - Reducing output of Penny?

[Alexander Geckeler]

Willi Reppel schrieb:
> Hi Alexander,
>
> I needed 1mW input to get 120 W out from a modified Icom 750 PA and 
> built a
> resistive PI- attenuator according to the attached copy of an ARRL 
> handbook.
> The chosen R1&R2 values for 25 dB attenuation reduce the 0.4 W output of
> Penny to 1 mW. Hope this info is useful for you.
>
> vy 73
> SM6OMH  Willi
>
> ----- Original Message ----- From: "Alexander Geckeler" 
> <alexander.geckeler at gmx.de>
> Cc: <hpsdr at lists.hpsdr.org>
> Sent: Sunday, March 01, 2009 8:41 PM
> Subject: Re: [hpsdr] QSO on 3 at 400 mW - Reducing output of Penny?
>
>
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> Lyle Johnson schrieb:
>>> ***** High Performance Software Defined Radio Discussion List *****
>>>
>>>> Yes - you can adjust the gain by band values in the PA Settings tab 
>>>> so you're only getting 10mW out when the main power out is set to 
>>>> 100%.
>>>
>>> Note that when you run the DAC at less than full scale, you begin to 
>>> reduce dynamic range.  Put another way, the Tx noise floor raises 
>>> and the relative level of Tx spurs increases by the amount you 
>>> reduce the signal from full scale.
>>>
>>> If you want to lower it a lot, you may want to consider using an 
>>> attenuator.
>>>
>>> 73,
>>>
>>> Lyle KK7P
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>> Hello Lyle and all!
>>
>> THX for your feedbacks!
>>
>> Re. attenuator: Is there a favour one, which is adequate for this 
>> purpose?
>>
>> 73,
>> Alexander
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>
>
Hello Willi,

many thanks for your answer.
I decided to use a 6db attenuator to reduce 0.4W output of Penny to 0.1W 
for driving the small 10W PA.

73, Alexander


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