Search String: Display: Description: Sort:


References: [ 490 ]

Total 490 documents matching your query.

1. [Amps] GS-35B (score: 1)
Author: TexasRF at (
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)
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)
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)
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)
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)
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)
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)
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)
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)
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)
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)
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 http://lists.contesting.c
/archives//html/Amps/2004-09/msg00247.html (7,726 bytes)

13. Re: [Amps] Equalising resistors with HV diodes (score: 1)
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)
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)
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)
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)
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)
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)
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)
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)

This search system is powered by Namazu