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Total 17 documents matching your query.

1. [AMPS] Henry 8K at 1500 watts Out -- Warning Long (score: 1)
Author: (Mike Willis)
Date: Wed, 09 Dec 1998 16:14:11 +0000
As long as the amplifier is correctly biased and not nearly in class C ! I found this out when a transistor amplifier bias failed because of a dry joint. Seemed linear from 10W-100W. Didn't check tha
/archives//html/Amps/1998-12/msg00168.html (8,825 bytes)

2. [AMPS] 3-500Z on 50MHz (score: 1)
Author: (Mike Willis)
Date: Thu, 19 Nov 1998 08:24:46 +0000
I am building an amplifier for 6m with a 3-500Z. I have 2.6kV EHT, plenty of drive and am looking for something like 500W of output. I can get 300W. I have had two problems. Firstly a nasty parasitic
/archives//html/Amps/1998-11/msg00271.html (7,714 bytes)

3. [AMPS] 4CX3000A - getting one tested? (score: 1)
Author: (Mike Willis)
Date: Tue, 06 Oct 1998 08:39:53 +0100
I have found that, when polished up and properly displayed, they have far more value as an ornament than as a practical amplifier for amateur radio. An excellent use for low emission 3-500Zs as well
/archives//html/Amps/1998-10/msg00032.html (7,591 bytes)

4. [AMPS] Re: Wanted: 2 X 4CX250r amp article (score: 1)
Author: (Mike Willis)
Date: Wed, 15 Jul 1998 15:04:47 +0100
Squeze it a bit! Do you have to replace the valves after each over? -- FAQ on WWW: Submissions: Administrative requests: amps-REQUEST@contes
/archives//html/Amps/1998-07/msg00079.html (7,698 bytes)

5. [AMPS] Low efficiency from AM6155 on 432 MHz (score: 1)
Author: (Mike Willis)
Date: Wed, 10 Jun 1998 09:04:21 +0100
I have now got an AM6155 running on 432MHz using the W3RJW mods to the RF cavity (need a new blower BTW) but although I get 300mA of anode current from a few watts of drive, I can not get more than 1
/archives//html/Amps/1998-06/msg00130.html (7,415 bytes)

6. [AMPS] A simple 4CX250 question (score: 1)
Author: (Mike Willis)
Date: Wed, 20 May 1998 08:17:25 +0100
I do not seem to have my data sheet to hand. I wonder what the optimim screen voltage is for the 4CX250K with 1.6kV on the anode, for SSB use with 100mA standing bias? Perhaps it does not matter so m
/archives//html/Amps/1998-05/msg00373.html (7,167 bytes)

7. [AMPS] A "no tune" amplifier output section/operationquestion. (score: 1)
Author: (Mike Willis)
Date: Tue, 07 Apr 1998 15:53:19 +0100
Another way is to use a transformer, as in audio amplifiers and most modern solid state HF radio amplifiers -- FAQ on WWW: Submissions: Admin
/archives//html/Amps/1998-04/msg00049.html (7,938 bytes)

8. [AMPS] Valve Amplifiers and Bad Matches (score: 1)
Author: (Mike Willis)
Date: Fri, 10 Apr 1998 19:59:23 +0100
I have a question regarding the AL80A. What is the maximum VSWR it can manage (all phases) to compensate for at say 500W output. Secondly, what is the range of resistance the PI-L output circuit can
/archives//html/Amps/1998-04/msg00082.html (7,073 bytes)

9. [AMPS] ARCING MORE (score: 1)
Author: (Mike Willis)
Date: Thu, 16 Apr 1998 08:16:39 +0100
It may be. Once the capacitor arced and the plates became deformed the arc persisted. The original cause of the arc was operator error, much of that cause will be treated by the extraction of the cos
/archives//html/Amps/1998-04/msg00103.html (9,052 bytes)

10. [AMPS] parasitics (score: 1)
Author: (Mike Willis)
Date: Wed, 22 Apr 1998 08:05:08 +0100
Almost certainly, but it is difficult owing to the EHT. If you design the PI-L circuit correctly, it will act like a low pass filter so ought to never be high Z at VHF. This does mean you have to us
/archives//html/Amps/1998-04/msg00214.html (9,603 bytes)

11. [AMPS] 3-500Z amplifiers and grid current (score: 1)
Author: (Mike Willis)
Date: Mon, 16 Mar 1998 11:22:13 +0000
How does one estimate the grid dissipation in valves like the 3-500Z, 3CX800 etc. DC Volts x DC amps is simple, RMS volts and RMS current also easy. But what about RF losses? Say I have 50W input to
/archives//html/Amps/1998-03/msg00320.html (8,288 bytes)

12. [AMPS] PT-1000-K1Mh (score: 1)
Author: (Mike Willis)
Date: Wed, 25 Mar 1998 13:28:44 +0000
I don't know but I am getting pretty sick of all this one theme argument. Lets have more discussion in other areas, e.g. VHF/UHF, experiences with the new tetrodes from Svetlana etc? -- FAQ on WWW:
/archives//html/Amps/1998-03/msg00404.html (8,619 bytes)

13. [AMPS] PT-1000-K1Mh (score: 1)
Author: (Mike Willis)
Date: Wed, 25 Mar 1998 15:35:20 +0000
OK. Many K2RIWs do not work while other seemingly identical ones do. Why? The K2 style cooling system has been used a lot with the 4CX250B. It does not provide an air blast to the base. Does this mat
/archives//html/Amps/1998-03/msg00408.html (9,030 bytes)

14. [AMPS] Plate RFC choke design (score: 1)
Author: (Mike Willis)
Date: Fri, 27 Mar 1998 08:51:28 +0000
This is certainly the way to go, but make sure you get them in the right order and space them well apart and mutually at right angles to the tank coil. -- FAQ on WWW:
/archives//html/Amps/1998-03/msg00442.html (8,449 bytes)

15. Re: [Amps] HF amp output power dropping (score: 1)
Author: Mike Willis <>
Date: Sat, 29 Sep 2007 22:06:48 +0100
Last time I had this happen it was the antenna. I think something was getting hot and changing the match. I am sure you are tuning it into a dummy load, so it can't be that. However, it was possibly
/archives//html/Amps/2007-09/msg00497.html (7,913 bytes)

16. Re: [Amps] HF amp output power dropping (score: 1)
Author: Mike Willis <>
Date: Sat, 06 Oct 2007 17:52:29 +0100
OK - That is interesting. While you have it set up, check that the power does not come back when you tune the input circuit. If you can not tune the input circuit, this might be your problem. If it d
/archives//html/Amps/2007-10/msg00063.html (9,655 bytes)

17. Re: [Amps] Amps Digest, Vol 64, Issue 5 (score: 1)
Author: Mike Willis <>
Date: Wed, 02 Apr 2008 21:24:44 +0100
For amplifiers using mechanical coaxial relays, TX/RX switching time depends mainly on the settling time of the coaxial relay. Here are some manufacturers figures. An sequencer will need to delay by
/archives//html/Amps/2008-04/msg00050.html (8,589 bytes)

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