[Amps] Amplifier Vs Plate Modulated

[Fuqua, Bill L]

  I did not deal with plate dissipation. 562.5 Watts power is the average power out for 1500 Watts PEP and 
100% sinewave modulation. Now at 60% efficiency that amounts to 375 Watts Plate Dissipation. So there are two limits.
One is the PEP output the amplifier can produce at low distortion, the second is the plate dissipation. You would have 
to chose the lowest of the two. However, most amplifiers will be PEP Power Output limited not plate dissipation limited.
  Please check my math.
73
bill wa4lav

________________________________________
From: Fuqua, Bill L
Sent: Saturday, November 28, 2015 7:29 PM
To: Roger (K8RI); amps at contesting.com
Subject: RE: [Amps] Amplifier Vs Plate Modulated

  By putting all the sideband power into one sideband you have a 3dB advantage over traditional AM because you could go to
a 3kHz IF filter rather than 6kHz.
73
Bill wa4lav


________________________________________
From: Fuqua, Bill L
Sent: Saturday, November 28, 2015 7:26 PM
To: Roger (K8RI); amps at contesting.com
Subject: RE: [Amps] Amplifier Vs Plate Modulated

   Lets see, for legal limit you will be limited to 1500W PEP/4 or 375 Watts of carrier.
Sideband power for will be half of that if you are running constant sinewave tone into your exciter so add another 187.5 Watts.
The total power output for 1500W PEP 100% plate modulated by sinewave is 562.5 Watts average power.
  Taking that into account I'd think most any modern full gallon amplifier could handle it.
You could half the bandwidth but still have the same effective modulation by running 375W carrier and 187.5 Watts into
one sideband only rather than split between two.
73
Bill wa4lav
________________________________________
From: Amps [amps-bounces at contesting.com] on behalf of Roger (K8RI) [k8ri at rogerhalstead.com]
Sent: Thursday, November 26, 2015 1:27 AM
To: amps at contesting.com
Subject: [Amps] Amplifier Vs Plate Modulated

I've posted the following on two group. They are not cross posted.
Please do not cross post answers.  If you must post to both groups,
please cut and past rather than cross posting.  Thanks!

OK, I understand, there's less iron in an amp Vs plate modulation, but
how about a low level carrier driving a legal limit, plate modulated
stage Vs a low level AM signal into a linear amp?.  Which is
preferable?  Not many commercial ham amps can stand up, to long winded,
AM transmissions and from my experience most AMers tend to be long
winded, me included.  I talk like I write<:-) However Plate modulated,
or linear amp, the power out limit is the same. With the new power
limitations, AM appears to be the only loser,

So, what is the advantages and disadvantages for each.  Yes, I
understand that many of today's rigs will run a nice clean  AM signal of
relatively low amplitude (25 to 75 watts, bearing in mind that the
dissipation in class A is driving the amp right to its limit.

I haven't run AM since the old plate modulated days. OTOH, I do run the
5000MP in class A to drive a Tetrode to the legal limit.  The 5000MP amp
only gets warm when run this way.  It gets hot if I reduce the drive.
Class A runs the maximum dissipation with no signal input to the final.

Thoughts?

73

Roger (K8RI)

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus


_______________________________________________
Amps mailing list
Amps at contesting.com
http://lists.contesting.com/mailman/listinfo/amps