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1. [Amps] Filament Transformer (score: 1)
Author: "David C. Hallam" <dhallam@rapidsys.com>
Date: Sun, 20 Jun 2004 10:50:55 -0400
I am building a linear using a 4CX1500A that needs about 38 amps at 5 volts for the filament. I have two identical 5V 21A filament transformers. Is there any reason why I can't wire the two in parall
/archives//html/Amps/2004-06/msg00109.html (6,594 bytes)

2. Re: [Amps] Filament Transformer & Zener Diodes (score: 1)
Author: "David C. Hallam" <dhallam@rapidsys.com>
Date: Tue, 22 Jun 2004 09:06:15 -0400
Thanks to all who replied to my request for help with filament transformers for my 4CX1500A. Now I have another question about something that never occurred to me before. For a zener regulated screen
/archives//html/Amps/2004-06/msg00113.html (7,865 bytes)

3. [Amps] Also Need a Door Knob Capacitor (score: 1)
Author: "David C. Hallam" <dhallam@rapidsys.com>
Date: Sun, 11 Jul 2004 12:41:41 -0400
I am looking for a ceramic door knob capacitor also. I need a 200 pf @ 10KVDC. It is one in the 80 meter coil assembly of a Butternut HF6V antenna. David C. Hallam KC2JD _____________________________
/archives//html/Amps/2004-07/msg00051.html (6,927 bytes)

4. [Amps] Where to get Lg Zeners? (score: 1)
Author: "David C. Hallam" <dhallam@rapidsys.com>
Date: Fri, 6 Aug 2004 08:54:46 -0400
As far as I know, Frank Fix at K2AW's Silicon Alley will still supply 50 watt zeners in about any value you want. Address in any issue of QST. David KC2JD ____________________________________________
/archives//html/Amps/2004-08/msg00052.html (7,369 bytes)

5. [Amps] RE: . zero-voltage triac power supply (Angel Vilaseca) (score: 1)
Author: "David C. Hallam" <dhallam@rapidsys.com>
Date: Tue, 10 Aug 2004 19:21:16 -0400
Message: 4 Date: Tue, 10 Aug 2004 09:33:49 +0200 From: Angel Vilaseca <avilaseca@bluewin.ch> Subject: [Amps] zero-voltage triac power supply To: AMPS@contesting.com Message-ID: <41187A5D.862A8E89@blu
/archives//html/Amps/2004-08/msg00090.html (9,745 bytes)

6. [Amps] Plate Load Impedance (score: 1)
Author: "David C. Hallam" <dhallam@rapidsys.com>
Date: Mon, 6 Sep 2004 21:26:06 -0400
I am going through the exercise to design the Pi-L network for a new amplifier. Calculating the plate load impedance by two different methods, I come up with two vastly different answers. With a tetr
/archives//html/Amps/2004-09/msg00145.html (7,371 bytes)

7. RE: [Amps] Plate Load Impedance (score: 1)
Author: "David C. Hallam" <dhallam@rapidsys.com>
Date: Thu, 9 Sep 2004 16:38:28 -0400
Gerald, I pulled out my copy of the RCA tube manual and read the section on AB1 amplifiers. I didn?t find anything that explicitly referred to a K factor for AB1, but then maybe my edition is an olde
/archives//html/Amps/2004-09/msg00175.html (9,512 bytes)

8. [Amps] James Millen Variable Capacitor (score: 1)
Author: "David C. Hallam" <dhallam@rapidsys.com>
Date: Tue, 21 Sep 2004 13:34:39 -0400
I have a James Millen air variable capacitor and the only marking I can find on it is 125Y5. None of my reference catalogs have any listing for Millen capacitors. Can anyone tell me what the capacita
/archives//html/Amps/2004-09/msg00390.html (7,374 bytes)

9. Re: [Amps] working out plate impedance for pi-network (score: 1)
Author: "David C. Hallam" <dhallam@rapidsys.com>
Date: Fri, 24 Sep 2004 08:11:08 -0400
Ian, I have just been through this exercise. The long answer is that the plate load impedance is the peak RF voltage divided by the peak fundamental RF plate current. These values are determined from
/archives//html/Amps/2004-09/msg00439.html (7,691 bytes)

10. [Amps] Vacuum Variable Capacitors (score: 1)
Author: "David C. Hallam" <dhallam@rapidsys.com>
Date: Sat, 25 Sep 2004 09:59:56 -0400
Has anyone had any experience with the Russian vacuum variable capacitors that are showing up on eBay? Are the mounting flanges and screw assemble to move the variable plate the same as Jennings, etc
/archives//html/Amps/2004-09/msg00449.html (6,624 bytes)

11. [Amps] Re: Transformer in GLA 1000 B : OK for 2xGI 7 ? (craxd) (score: 1)
Author: "David C. Hallam" <dhallam@rapidsys.com>
Date: Wed, 6 Oct 2004 08:41:35 -0400
In the old Bill Orr Radio Handbooks, he presents a graph of transformer core weight vs. power capacity for various duty cycles. Admittedly it is an approximation with a couple of caveats for ICAS ser
/archives//html/Amps/2004-10/msg00058.html (7,333 bytes)

12. Re: [Amps] Blowing off steam (score: 1)
Author: "David C. Hallam" <dhallam@rapidsys.com>
Date: Wed, 20 Oct 2004 19:50:59 -0400
My two cents worth: What's illegal, immoral, or unfair about sniping? The only reason you get outbid by a sniper is because he's will to pay more for an item than you are. The high bidder is the high
/archives//html/Amps/2004-10/msg00337.html (9,528 bytes)

13. [Amps] HT57 Capacitors (score: 1)
Author: "David C. Hallam" <dhallam@rapidsys.com>
Date: Sat, 4 Dec 2004 12:25:52 -0500
Does anyone have a HT57 200 pF 15kV capacitor for sale? I need one for my Butternut HF6V antenna. David C. Hallam KC2JD _______________________________________________ Amps mailing list Amps@contesti
/archives//html/Amps/2004-12/msg00071.html (6,665 bytes)

14. [Amps] Re: Rm resistor (score: 1)
Author: "David C. Hallam" <dhallam@rapidsys.com>
Date: Tue, 14 Dec 2004 12:46:54 -0500
I had intended to do something similar to this to a new amplifier to establish the correct position for the taps on the coils. I am a little puzzled about how to go about it for a Pi-L network. I pla
/archives//html/Amps/2004-12/msg00214.html (7,567 bytes)

15. [Amps] Y-180 (score: 1)
Author: "David C. Hallam" <dhallam@rapidsys.com>
Date: Sat, 1 Jan 2005 13:28:18 -0500
Can anyone identify a Y-180 tube? I have several and don't know what they are. They look like a 4CX300. They are not listed in my Eimac catalog. David C. Hallam KC2JD ________________________________
/archives//html/Amps/2005-01/msg00001.html (6,980 bytes)

16. RE: [Amps] PLATE RESISTENCE (score: 1)
Author: "David C. Hallam" <dhallam@rapidsys.com>
Date: Thu, 6 Jan 2005 14:44:27 -0500
Chris, The Q of the circuit is not a derived value. You select the operating Q you want to use and then calculate the values of capacitance and inductance for the Pi circuit. A value of 10 to 15 is u
/archives//html/Amps/2005-01/msg00082.html (7,156 bytes)

17. [Amps] Small Amplifier (score: 1)
Author: "David C. Hallam" <dhallam@rapidsys.com>
Date: Fri, 14 Jan 2005 11:26:18 -0500
I want to build a new small amplifier for those times when I really don't want to heat up the shack with the 5CX1500A. I have a supply of 4CX300's and sockets as well as 4CX250's and sockets. I plan
/archives//html/Amps/2005-01/msg00257.html (7,013 bytes)

18. [Amps] Re: OT: Anyone know of any RF Speech Processor Kits? (score: 1)
Author: "David C. Hallam" <dhallam@rapidsys.com>
Date: Sat, 15 Jan 2005 12:27:50 -0500
I have a RF speech processor that I built from a 1970's article in Ham Radio. There were a several different construction articles for RF processors that appeared in Ham Radio over the years. Mine us
/archives//html/Amps/2005-01/msg00278.html (7,059 bytes)

19. [Amps] 4CX250 Grounded Grid (score: 1)
Author: "David C. Hallam" <dhallam@rapidsys.com>
Date: Tue, 18 Jan 2005 08:44:25 -0500
The 4CX250B can be operated in grounded grid. However, you cannot tie the screen grid to the grounded control grid. Normal screen voltage must be supplied to it. Look in any of the Bill Orr handbooks
/archives//html/Amps/2005-01/msg00341.html (6,762 bytes)

20. [Amps] Re: Re: Small Amplifier (score: 1)
Author: "David C. Hallam" <dhallam@rapidsys.com>
Date: Tue, 18 Jan 2005 12:34:56 -0500
IMO The best way to do this is to use a passive grid driven mode for the 4CX250B's where you can adjust the noninductive grid resistor to get the proper grid voltage swing based on the output of your
/archives//html/Amps/2005-01/msg00350.html (7,915 bytes)

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