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1. [Amps] GS-35B (score: 1): Author: TexasRF at aol.com (TexasRF@aol.com); Date: Mon Aug 18 21:59:13 2003; Hi Arnie, I have three of these tubes that are unused and I don't think I will need them for projects that were planned at the time. I paid $200 total for them and would like to recover my cost if yo; /archives//html/Amps/2002-09/msg00398.html (6,572 bytes)
2. Re: [Amps] Homebrew "Hi-Pot" design issues (score: 1): Author: TexasRF@aol.com; Date: Mon, 12 Jan 2004 10:45:17 EST; Emco makes a potted module that ouputs 0 to 10kv at .2ma with .7 to 15vdc input. They are available on Ebay for about $40 by searching for "10kv". I use one of these and my trusty old Heathkit VOM on; /archives//html/Amps/2004-01/msg00133.html (8,769 bytes)
3. Re: [Amps] Re: matching network (score: 1): Author: TexasRF@aol.com; Date: Wed, 28 Jan 2004 10:38:32 EST; A cathode driven configuration doesn't inherently cause excessive grid current. If proper grid and screen voltages are supplied, the grid current is a function of grid bias voltage and drive level, j; /archives//html/Amps/2004-01/msg00321.html (8,677 bytes)
4. Re: [Amps] Re: matching network (score: 1): Author: TexasRF@aol.com; Date: Wed, 28 Jan 2004 16:48:47 EST; One further clarification, in grid driven configuration: yes, the screen is grounded for r.f. but so is the cathode (less so if a degeneration resistor is used), so the drive is still applied between; /archives//html/Amps/2004-01/msg00328.html (8,169 bytes)
5. Re: [Amps] Re: matching network (score: 1): Author: TexasRF@aol.com; Date: Thu, 5 Feb 2004 10:40:58 EST; I have heard the term "super cathode drive" many times but have not seen an explanation of what it means. A Google search turns up links that mention super cathode drive and G2DAF circuits but no rea; /archives//html/Amps/2004-02/msg00036.html (7,838 bytes)
6. Re: [Amps] Re: matching network (score: 1): Author: TexasRF@aol.com; Date: Fri, 6 Feb 2004 12:32:46 EST; Ref: Triode vs Tetrode/Cathode Drive If you compare data sheets of a couple of modern popular tubes, 8877 triode and GS23B tetrode, with cathode drive you find both tubes have a rated transconductanc; /archives//html/Amps/2004-02/msg00043.html (10,359 bytes)
7. Re: [Amps] 2 x 8877 (score: 1): Author: TexasRF@aol.com; Date: Tue, 2 Mar 2004 12:20:09 EST; Whoa, wait a minute! That 150cm by 100 cm opening might be a waveguide beyond cutoff but the attenuation for this size opening is pretty low according to the Bill Orr Radio Handbook. The chart for th; /archives//html/Amps/2004-03/msg00021.html (8,004 bytes)
8. Re: [Amps] AMP INT LK500ZC (score: 1): Author: TexasRF@aol.com; Date: Sat, 6 Mar 2004 10:14:37 EST; Also, along the lines suggested by George, K6GT, the usual zener diode mounting insulators are fairly fragile and can allow a sneak cathode to ground path. This typically happens as a result of a pla; /archives//html/Amps/2004-03/msg00062.html (7,098 bytes)
9. Re: [Amps] Plate Load Impedance (score: 1): Author: TexasRF@aol.com; Date: Tue, 7 Sep 2004 10:28:39 EDT; The RCA Power Tube book shows plate load impedance= (plt voltage/plt current)/K factor. Note that plate voltage is the d.c. value from the power supply and plate current is as measured by the d.c. pl; /archives//html/Amps/2004-09/msg00160.html (7,889 bytes)
10. Re: [Amps] ARCO compression trimmer caps (score: 1): Author: TexasRF@aol.com; Date: Sat, 11 Sep 2004 10:24:36 EDT; I see that McMaster online has 12-38 and 1/8-40 hand taps listed. Perhaps one of these is what you need to rethread a new, smaller nut to fit. 73/k5gw _______________________________________________; /archives//html/Amps/2004-09/msg00193.html (7,190 bytes)
11. Re: [Amps] Dipped Mica Caps (score: 1): Author: TexasRF@aol.com; Date: Sat, 11 Sep 2004 10:28:02 EDT; Hi John, RF Parts has quite a few Mica Caps listed up to 1000v if that is enough. If you don't have a copy of their 2004 Catalog you should call them for one; it has a lot of very usefull amplifier r; /archives//html/Amps/2004-09/msg00194.html (6,572 bytes)
12. Re: [Amps] Recommend supplier for aluminum sheet? (score: 1): Author: TexasRF@aol.com; Date: Mon, 13 Sep 2004 10:09:10 EDT; The aluminum box maker is Charlie Byers, K3IWK. He advertises regularly in QST. 73/k5gw _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.c; /archives//html/Amps/2004-09/msg00247.html (7,726 bytes)
13. Re: [Amps] Equalising resistors with HV diodes (score: 1): Author: TexasRF@aol.com; Date: Tue, 21 Sep 2004 10:29:41 EDT; So we have a string of diodes with a few microamps flowing in the reverse direction. If one of the diodes is rated for 200v and and there is 300v across it, will it fail? I guess I haven't seen the e; /archives//html/Amps/2004-09/msg00378.html (8,114 bytes)
14. [Amps] filament voltage question (score: 1): Author: TexasRF@aol.com; Date: Wed, 27 Oct 2004 12:34:22 EDT; I am looking for some advice on adjusting the filament voltage on a TH347 tetrode used in my 1296mhz cavity amplifier. The TH347 is a directly heated cathode tube. Due to a long underground run for t; /archives//html/Amps/2004-10/msg00447.html (8,687 bytes)
15. Re: [Amps] toroid filament choke? (score: 1): Author: TexasRF@aol.com; Date: Wed, 27 Oct 2004 12:57:11 EDT; The filament transformer will limit the current to a large extent. Also, the resistance of the filament or heater will rise very quickly when the voltage is applied. For example, the TH347 filament r; /archives//html/Amps/2004-10/msg00450.html (7,878 bytes)
16. Re: [Amps] Amp failure advice please. (score: 1): Author: TexasRF@aol.com; Date: Mon, 15 Nov 2004 10:18:05 EST; I have a 70cm amplifier that recently showed exactly the same symptoms described. The problem turned out to be a shorted coax jumper (approx 6 inches long) between the amplifier output connector and; /archives//html/Amps/2004-11/msg00214.html (6,957 bytes)
17. Re: [Amps] High C out (score: 1): Author: TexasRF@aol.com; Date: Fri, 21 Jan 2005 12:19:00 EST; Makes one wonder if just increasing the inductance of the strap from the tube anode to the capacitor would be enough to allow resonance. Three easy ways to do this: 1> make it longer or 2>make it nar; /archives//html/Amps/2005-01/msg00415.html (6,579 bytes)
18. Re: [Amps] 10 DB increase (score: 1): Author: TexasRF@aol.com; Date: Sat, 5 Feb 2005 11:20:59 EST; Here is another weird theory: The ionosphere is not like a length coaxial cable with fixed and predictable loss; there are fluctuations in the loss that are not fixed and predictable. If we make a te; /archives//html/Amps/2005-02/msg00151.html (6,387 bytes)
19. Re: [Amps] 10dB and propagation (score: 1): Author: TexasRF@aol.com; Date: Tue, 8 Feb 2005 22:46:01 EST; I don't recall any mention of polarization changes in this discussion. Being an EME operator I am keenly aware of the faraday rotation problem at VHF. As the frequency is lowered the rotation speed i; /archives//html/Amps/2005-02/msg00328.html (8,538 bytes)
20. Re: [Amps] 8877 Test (score: 1): Author: TexasRF@aol.com; Date: Mon, 14 Feb 2005 10:38:27 EST; Hi alex and all, This is a true story: About a year ago I was given an unused 8877 that was about 20 years old. After all the warnings about firing up old tubes, I used my newly acquired solid state; /archives//html/Amps/2005-02/msg00478.html (8,523 bytes)

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