? What is the likely Z of a high-Q series-resonant circuit on frequencies above and below the frequency of resonance? As I recall, you measured an AL80 Tune-C series-resonance at c. 180MHz, and the
? I agree that not much VHF energy can make it to the tube. The VHF energy comes not from the transceiver. It comes from damped-wave ringing in the anode-resonant circuit. This (VHF) ringing occurs
I disagree, Tom. While some parasitic oscillations in amplifiers are well behaved, some are not. In my 4-1000A, for the longest time while building it I had a slight oscillation that I could produce
HOW? How does closing a relay wether it is a hot closure or not produce a transient in anode current? I always thought anode current (other than bias current) was produce by a driving signal. Hot sw
"Hot switching" causes a transient in anode current by changing the load (specifically, the plate load impedence). Once the output contacts close, the impedence changes abruptly and there is a disco
OK, agreed. I should have been more specific. Rich was talking about how hot switching the INPUT of an amp causes an anode transient. That's what I have a difficulty with. Problems with hot switchin
? Very much like a hammer (the transient) striking a bell (the resonant circuit). This is how spark transmitters worked in days of yore. Rich... R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/mea
? A spark is reliable producer of wide-band feculence. ? hotswitching causes a spark. ? The spark is connected to a wire that connects to the input of the tube. ? When I was on 1296MHz, I could hear
Is the amplitude of a spark that is generated by hotswitching a 100W signal on the input relay really large enough to drive the tube and thereby generate a change in anode current on the output? 73,
Hi Jon, Same in amps here. When I make them oscillate, they generate trash and draw current. No bangs, no arcs, no bent tubes, etc. Ahh. But that was likely a fundamental oscillation, or a low order
Come on Rich, use your head. The low pass system on the input of the amp virtually guaranties the rise time of any pulse is about the same as the rise time of the desired signal. That's very well kno
Isn't this one of the 'does the sound exist in the forest if no one is there to hear it?' type arguments? If there's an arc at the input applied to the amplifier, it is coincidental in arriving at th
That's why the design should employ a grid-current overload tripoff. It's just funny that commercial manufacturers of That's probably because commercial PAs aren't driven with 775DSP's and aren't re
OK. Since I have no idea of the frequency the oscillation occured at, I can't confirm or refute your statement. 73, Jon KE9NA -- The Second Amendment is NOT about duck hunting! Jon Ogden jono@entera
MY POINT EXACTLY! Let's nor forget too, that as you increase in frequency, the output capacitance of the tube becomes a greater percentage of the total first capacitance in the tank circuit (C1 = Ct
I'll play devil's advocate here. Assume that the parasitic circuit consists of the tube output capacity in series with the inductance of the connection between the plate and the tune capacitor (and t
Author: Donald.Kessler@wpafb.af.mil (Kessler Donald J LtC AFMC/DOOT)
Date: Mon, 7 Jun 1999 11:22:49 -0400
Greetings all... I've been following this thread with much interest as I received two TL-922A amps from the MARS program. While these amps had very little time on them, one of the amps had significan
Author: Donald.Kessler@wpafb.af.mil (Kessler Donald J LtC AFMC/DOOT)
Date: Mon, 7 Jun 1999 11:30:42 -0400
I hate spell checkers... It changed my call... 73 again de Don (ki6sz) Come on Rich, use your head. The low pass system on the input of the amp virtually guaranties the rise time of any pulse is abou
? One of the seemingly better articles on the treatment of vhf parasitics was written by a commercial amplifier engineer who worked for the General Electric Co. ("Parasites and Instability in Radio