[Lowfer] " XR's " first WSPR weekend

[John Andrews]

Andy,

OK. If you terminate the input to the amp (left side of the 180 Ohm 
resistor) with 50 Ohms (maybe like two 100 Ohm 2 watt resistors in 
parallel), and then connect the transceiver, what happens with the 
antenna current as you bring up the transceiver output?

John A.

On 12/6/2010 4:10 PM, Andy - KU4XR wrote:
> John:  Link to the PA schematic:
>
> http://ku4xr.webs.com/apps/photos/photo?photoid=108936955
>
> I'm sorry, when I try to explain what I'm doing, it's all too
> easy to get mW, and mA interchanged in my typing.
>
> As it should be, the reference is to MilliAmps of RF Current,
> and not MilliWatts...slip up on my part;
>
>
>
>
> Andy - KU4XR - EM75xr - Friendsville, TN. USA
>
> LOWfer Beacon " XR "
>
> --- On Mon, 12/6/10, John Andrews<w1tag at charter.net>  wrote:
>
>> From: John Andrews<w1tag at charter.net>
>> Subject: Re: [Lowfer] " XR's " first WSPR weekend
>> To: "Discussion of the Lowfer (US, European,&  UK) and MedFer bands"<lowfer at mailman.qth.net>
>> Date: Monday, December 6, 2010, 4:02 PM
>> Andy,
>>
>>> *** How ever accurate the power test may be; the meter
>> shows
>>> 1-1/2 watts output into the 50 Ohm dummy load MAX, and
>> distorted,
>>> using a 1500 cycle tone. For a clean output, it shows
>> .75 watts .
>>
>> That's 17 volts peak to peak across 50 Ohms. That's more
>> than enough to
>> drive any 1 watt Class D. PA. Did you have a 50 Ohm
>> termination at the
>> input of the PA? Is there a schematic of the PA available?
>>
>>> I can connect the radio directly to the 50 Ohm LPF,
>> and see
>>> 60 mW of RF current on the RF ammeter running wide
>> open........
>>> I connected the radio output thru a .33µF cap to the
>> input of the
>>> Class " D " amp, and got 90 mW of RF thru it..
>> Disappointment !!
>>
>> Are you doing a calculation to get those mW readings from
>> the antenna
>> ammeter, or are you talking about the antenna current in
>> mA?
>>
>> John, W1TAG
>> ______________________________________________________________
>
> ______________________________________________________________
> Lowfer mailing list
> Home: http://mailman.qth.net/mailman/listinfo/lowfer
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Lowfer at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>