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81. Re: [Amps] every db lost re Tubes vs. Solid State (score: 1)
Author: Larry Benko <xxw0qe@comcast.net>
Date: Mon, 30 Apr 2012 20:45:21 -0600
Nevertheless, mismatch losses are a BIG deal to the cellular folks. They do exist and can easily be seen at much lower frequencies with cheap connectors that are not correctly designed and also if te
/archives//html/Amps/2012-04/msg00319.html (9,030 bytes)

82. [Amps] Mismatch loss (score: 1)
Author: Larry Benko <xxw0qe@comcast.net>
Date: Wed, 02 May 2012 12:42:48 -0600
I have started a new topic. Both. See the family of curves in the ARRL Handbook for excess attenuation due to mismatch, which has been in every edition of the handbook since I've been buying it (the
/archives//html/Amps/2012-05/msg00071.html (12,597 bytes)

83. Re: [Amps] Mismatch loss (score: 1)
Author: Larry Benko <xxw0qe@comcast.net>
Date: Wed, 02 May 2012 13:50:49 -0600
Don, No, reflection coefficient = sqrt{ [(Rload - Ro)^2 + Xload^2] / [(Rload + Ro)^2 + Xload^2] } and SWR = (1 + reflection coeff))/(1 - reflection coeff) where Ro = characteristic/surge impedance of
/archives//html/Amps/2012-05/msg00081.html (10,795 bytes)

84. Re: [Amps] Mismatch loss (score: 1)
Author: Larry Benko <xxw0qe@comcast.net>
Date: Wed, 02 May 2012 19:21:46 -0600
Jim, You keep changing the topic. My original comment was that 2 UHF connector pairs separated by 155 degrees (worst case) of 50 ohm cable on 70cm _can_ produce slightly over a 2:1 SWR with low loss
/archives//html/Amps/2012-05/msg00096.html (13,319 bytes)

85. Re: [Amps] Tubes vs. Solid State (score: 1)
Author: Larry Benko <xxw0qe@comcast.net>
Date: Thu, 03 May 2012 11:41:15 -0600
Bob, Something doesn't sound right here. Even if your amp produced a perfect square wave output, the harmonics of the square wave would be down more than what you saw. The Fourier series of a square
/archives//html/Amps/2012-05/msg00124.html (14,895 bytes)

86. Re: [Amps] Tubes vs. Solid State (score: 1)
Author: Larry Benko <xxw0qe@comcast.net>
Date: Thu, 03 May 2012 12:16:22 -0600
Bob, I am currently experimenting with one of the smaller Freescale parts. I do not see any reference to the -7dBc spec in any of the datasheets. On the other hand I have seen the output waveform loo
/archives//html/Amps/2012-05/msg00126.html (19,151 bytes)

87. Re: [Amps] Dummy Load Blues (score: 1)
Author: Larry Benko <xxw0qe@comcast.net>
Date: Thu, 14 Jun 2012 22:08:32 -0600
Manfred, Just FYI. Using your numbers and assuming the SWR issues are excess inductance, the inductance necessary to turn 50 ohms to a 1.5:1 SWR on 2m is ~23nH. If you were to put 8pF from the center
/archives//html/Amps/2012-06/msg00128.html (10,647 bytes)

88. Re: [Amps] Pi-L Network Question (score: 1)
Author: Larry Benko <xxw0qe@comcast.net>
Date: Mon, 18 Jun 2012 13:09:01 -0600
Jim, I have often wondered this very thing and recently built several filters and have made several measurements. The effects of coupling between the coils are primarily stopband attenuation. Small a
/archives//html/Amps/2012-06/msg00251.html (10,222 bytes)

89. Re: [Amps] Pi-L Network Question (score: 1)
Author: Larry Benko <xxw0qe@comcast.net>
Date: Mon, 18 Jun 2012 13:29:16 -0600
Jim, On the comparison between a PI and a PI-L network: PI needs to be run at a higher Q than the PI-L for the same stopband attenuation resulting in sharper tuning as you QSY. PI needs 1 fewer poles
/archives//html/Amps/2012-06/msg00252.html (9,692 bytes)

90. Re: [Amps] Neon xfmr for HiPot (score: 1)
Author: Larry Benko <xxw0qe@comcast.net>
Date: Wed, 18 Jul 2012 10:17:13 -0600
I have a couple of fuel oil ignition transformers I use for this exact purpose. They are rated at 23mA and they actually work very well as current limited sources. They will produce 10kV @ 23mA or 10
/archives//html/Amps/2012-07/msg00219.html (9,853 bytes)

91. Re: [Amps] Forms for air wound coils (score: 1)
Author: Larry Benko <xxw0qe@comcast.net>
Date: Mon, 23 Jul 2012 19:56:23 -0600
Looking at the continuous air service temperatures for common plastics shows Teflon = 500F and PEEK = 480F and amazingly Polycarbonate (Lexan) = 475F. I usually use PEEK as I can get scraps from a lo
/archives//html/Amps/2012-07/msg00251.html (8,698 bytes)

92. Re: [Amps] IMD test question (score: 1)
Author: Larry Benko <xxw0qe@comcast.net>
Date: Wed, 01 Aug 2012 14:36:10 -0600
Bill, I have made amp IMD measurements with the circuit shown at http://www.w0qe.com/Technical_Topics/imd_testing_of_amplifiers.html which can measure any amp currently made. As I'm sure you are awar
/archives//html/Amps/2012-08/msg00015.html (8,835 bytes)

93. Re: [Amps] IMD test question (score: 1)
Author: Larry Benko <xxw0qe@comcast.net>
Date: Wed, 01 Aug 2012 23:39:45 -0600
Jim, There are NO radios currently made (that I know of) that are capable with 2 audio tones input of having output IMD <-60dBc when driving even a dummy load. Even when driving the radio to 1/2 or 1
/archives//html/Amps/2012-08/msg00032.html (13,303 bytes)

94. Re: [Amps] 4CX1500B project - swamped grid (score: 1)
Author: Larry Benko <xxw0qe@comcast.net>
Date: Fri, 10 Aug 2012 21:55:13 -0600
Hank, I hope someone will correct me if I am wrong but I believe the problem is the changing input impedance the tube/FET etc. throughout the RF cycle for all classes of operation except heavy class
/archives//html/Amps/2012-08/msg00170.html (13,898 bytes)

95. Re: [Amps] 4CX1500B project - swamped grid (score: 1)
Author: Larry Benko <xxw0qe@comcast.net>
Date: Sat, 11 Aug 2012 07:02:23 -0600
Peter, I can't quantify the change which is probably small but a professor I had in a EE class was emphatic about this topic. At the time I probably didn't grasp it completely. There should be a cont
/archives//html/Amps/2012-08/msg00173.html (15,106 bytes)

96. Re: [Amps] ALC Overshoot FTDX-5000 (score: 1)
Author: Larry Benko <xxw0qe@comcast.net>
Date: Mon, 13 Aug 2012 22:42:32 -0600
Not to nit pick but 60wpm is 20.0ms/dit. Letter spacing = 3 dits and word spacing = 7dits P = 11 + 3 A = 5 + 3 R = 7 + 3 I = 3 + 3 S = 5 + 7 Total = 50 dit times Therefore dit time = 1.2 / WPM 73, La
/archives//html/Amps/2012-08/msg00195.html (11,886 bytes)

97. Re: [Amps] Blue Disc Ceramic caps ?? (score: 1)
Author: Larry Benko <xxw0qe@comcast.net>
Date: Thu, 16 Aug 2012 22:01:48 -0600
Hank, Look at TDK CC45 capacitors. Available at Mouser with number 810-CC45xxxxxxxx. They are about $.15 in 1k quantities. The data sheet specifically says "low dissipation at high frequency". They a
/archives//html/Amps/2012-08/msg00267.html (7,737 bytes)

98. Re: [Amps] Multi-Amp w/ Power Combiners (score: 1)
Author: Larry Benko <xxw0qe@comcast.net>
Date: Thu, 23 Aug 2012 08:02:02 -0600
In a general RF power combiner the difference of amplitudes or phases between the 2 sources to be combined has the following effects. 1.) Equal TX amplifier amplitudes and phases = max. power output
/archives//html/Amps/2012-08/msg00361.html (9,115 bytes)

99. Re: [Amps] Multi-Amp w/ Power Combiners (score: 1)
Author: Larry Benko <xxw0qe@comcast.net>
Date: Fri, 24 Aug 2012 12:00:43 -0600
Generally yes if the combined port is at the correct impedance. The term you asking about is called isolation and it is specified port to port and is a function of terminating impedances. If you care
/archives//html/Amps/2012-08/msg00390.html (9,940 bytes)

100. Re: [Amps] diodes for motor driven vacuum variable (score: 1)
Author: Larry Benko <xxw0qe@comcast.net>
Date: Sat, 25 Aug 2012 22:09:15 -0600
Jim, Let's assume for a minute that there are only 2 diodes and the 3rd one is maybe something like a zener as only 2 diodes are needed for the usual limit switch circuitry. Also I am assuming that t
/archives//html/Amps/2012-08/msg00432.html (8,003 bytes)

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