1/4 vs 1/2 wavelength antenna

[Tom Ring]

I read in sci.electronics.design that Tom Ring <[email protected]>
wrote (in <[email protected]>) about '1/4 vs
1/2 wavelength antenna', on Thu, 3 Mar 2005:




See the last sentence, about the effect of an **8 ohm** source impedance
on damping.

Oh, and going from 8 ohms output impedance to 10e-7 (unless I
miscounted) would take the damping factor from 1 to 8e7, which is a bit
more than 2. Ignoring the speaker wires of course.

tom
K0TAR

 

[John Woodgate]

I read in sci.electronics.design that Tom Ring <[email protected]>

Oh, and going from 8 ohms output impedance to 10e-7 (unless I
miscounted) would take the damping factor from 1 to 8e7, which is a bit
more than 2. Ignoring the speaker wires of course.

Also ignoring the ***voice-coil resistance***. If that is included, as
it must be for a correct analysis, you get 2.

F Langford-Smith 'invented' the concept of damping factor, and around
1949 accepted the point made by James Moir that, by not properly taking
into account the effect of the voice-coil resistance, it was a seriously
misleading concept. Yes, 60 years later, people are still being misled.

 

[Tom Ring]

I read in sci.electronics.design that Tom Ring <[email protected]>
wrote (in <[email protected]>) about '1/4 vs
1/2 wavelength antenna', on Fri, 4 Mar 2005:

Also ignoring the ***voice-coil resistance***. If that is included, as
it must be for a correct analysis, you get 2.

F Langford-Smith 'invented' the concept of damping factor, and around
1949 accepted the point made by James Moir that, by not properly taking
into account the effect of the voice-coil resistance, it was a seriously
misleading concept. Yes, 60 years later, people are still being misled.

Good point. I stand corrected.

The only nit I would pick would be that impedance be used, since you
need to measure it at the frequency(ies) in question, not DC. And then
there is that pesky crossover in most systems. Personally I like biamping.

tom
K0TAR

 

[Leon Heller]

Nice articulation. I don't know who OM is, but RF transmitter power amps
are
not "impedance matched." Neither are audio power amps for that matter.

'OM' is radio ham speak for 'Old man'.

Leon

 

[John Woodgate]

I read in sci.electronics.design that Tom Ring <[email protected]>

Personally I like
biamping.

So do I.