jeremy-ca wrote:
> I remember reading a letter from Kenwood about 20 years ago that stated that
> their SS PA stages were designed to operate into 25-75 Ohm loads since 50
> Ohm cable was not a world wide standard.
>
> Ive been operating my TS-940's ( and TS-930's before that) into 75 Ohm loads
> since the late 80's with no difficulty and no power foldback. I do not use
> an antenna tuner, built in or external.
>
Many years ago in a different life I was in the amateur radio business
when it was quite profitable. I used to loan out an HF transceiver or
two to local groups for special operations, FD, or demonstrations.
These were all solid state. When asked about antennas I used to tell
them to use what ever was handy. Many times the antenna was nothing more
than a wire stuck in the coax jack. Who knows what the impedances those
finals saw. Over the years I only lost one set of finals and the
manufacturer replaced the entire final unit, not just the transistors.
73
Roger (K8RI)
www.rogerhalstead.com
>
> Carl
> KM1H
>
>
> ----- Original Message -----
> From: "David Cutter" <d.cutter@ntlworld.com>
> To: <amps@contesting.com>
> Sent: Sunday, March 09, 2008 8:18 AM
> Subject: Re: [Amps] Transceiver Output Impedance
>
>
>
>> One of these days I will try the following experiment.
>>
>> I will MAKE a rf signal generator and add resistance in series with it to
>> a
>> load of 50ohms and stop adding resistance when the load voltage is half
>> the
>> open circuit voltage. I will then assume this signal generator has an
>> output impedance of 50ohms. OR I will take a "known" 50ohm signal
>> generator
>> and test it for open and loaded output voltage.
>>
>> Then I will take say an ICE bandpass filter that has been tested on
>> someone
>> else's high grade test rig and characterise it on my signal generator with
>> a
>> 50ohm load.
>>
>> Then I will do the same with a transmitter and see if the results are the
>> same. If they are, I will assume that my transmitter is also 50ohm
>> "output
>> impedance."
>>
>> Then I will be more sure which side of the fence to drop.
>>
>> I suspect the output impedance of a broad band amplifer with L-C low pass
>> filters and transformer matching stages (possibly even feedback,
>> feedforward, stabilisation, etc ) does transmission line stuff and is not
>> just like a resistor in series with a zero source (Thevenin).
>>
>> The heavy weights have been arguing about this for quite a while and I've
>> seen magazine articles on the subject.
>>
>> David
>> G3UNA
>>
>>
>> _______________________________________________
>> Amps mailing list
>> Amps@contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>>
>>
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|