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81. Re: [Amps] Pin Diodes (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Wed, 8 Mar 2006 17:42:27 +0000
I have only tested HC-1s, but it's the same as you get with your circuit... and exactly the same as I posted two weeks ago :-) -- 73 from Ian GM3SEK _______________________________________________ Am
/archives//html/Amps/2006-03/msg00213.html (8,895 bytes)

82. Re: [Amps] Threads - was idiocy - perhaps it still is (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Tue, 14 Mar 2006 19:16:00 +0000
A few months ago, I had the pleasure of touring the Bletchley Park ENIGMA station with Roy Lewallen, W7EL. They have all kinds of related exhibits there, including a fine display of old communication
/archives//html/Amps/2006-03/msg00372.html (8,640 bytes)

83. Re: [Amps] Microwave Oven Autopsy (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Thu, 16 Mar 2006 07:45:40 +0000
Another important difference is in the load it's designed for. In DC terms, a magnetron is a diode. It has no control grid, so it needs a current-limiting supply to prevent runaway damage. This is co
/archives//html/Amps/2006-03/msg00430.html (8,865 bytes)

84. Re: [Amps] Washing equipment (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Thu, 16 Mar 2006 08:59:55 +0000
Paul later confirmed that the ultrasonic bath contained water plus a small amount of detergent or wetting agent. The water ended up a dirty brown but the rig came out sparkling. His friend's firm rou
/archives//html/Amps/2006-03/msg00434.html (8,909 bytes)

85. Re: [Amps] HV switching power supplys? (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Fri, 17 Mar 2006 19:53:07 +0000
The increasing number of "vacation DXpeditions", along with declining sunspot numbers, means the demand for lightweight, reliable power amplifiers is stronger than ever before. Everybody can run 100
/archives//html/Amps/2006-03/msg00521.html (8,924 bytes)

86. Re: [Amps] CD Cap (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Thu, 23 Mar 2006 08:01:56 +0000
First question is: what is the ripple current rating? Don't commit yourself to using them until you know. The ripple current rating is about internal heating, which has a large effect on capacitor li
/archives//html/Amps/2006-03/msg00611.html (8,243 bytes)

87. Re: [Amps] CD Cap (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Fri, 24 Mar 2006 00:33:59 +0000
Ripple current rating is the amount of alternating current that the capacitors can pass without too much internal heating. In a capacitor input supply, the caps are only charged in the parts of the c
/archives//html/Amps/2006-03/msg00631.html (9,368 bytes)

88. Re: [Amps] CD Cap (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Fri, 24 Mar 2006 06:24:50 +0000
As seen from here in GMT country, you're already on permanent night shift, so the meds should be bringing you double pay. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.if
/archives//html/Amps/2006-03/msg00633.html (7,497 bytes)

89. Re: [Amps] CD Cap (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Sat, 25 Mar 2006 18:25:04 +0000
For the DC current of a single 3-500Z you should be fine.... but to answer your original question, do leave some air circulating space between them. From a quick run through the PSU Designer program,
/archives//html/Amps/2006-03/msg00663.html (9,274 bytes)

90. Re: [Amps] Need some 220K 2 watt carbon resistors (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Mon, 27 Mar 2006 07:08:48 +0100
Strongly agree! Solid carbon (or carbon composition) resistors were the best available in Days of Old, but it would be a mistake to use them as replacements today. For cap equalizers and other applic
/archives//html/Amps/2006-03/msg00680.html (7,987 bytes)

91. Re: [Amps] Need some 220K 2 watt carbon resistors (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Tue, 28 Mar 2006 21:00:20 +0100
Where do Ohmite specify the inductance of these resistors, or show how they are made? We're straying away from the original topic, where inductance doesn't matter at all, but many metal film resistor
/archives//html/Amps/2006-03/msg00709.html (12,037 bytes)

92. Re: [Amps] Need some 220K 2 watt carbon resistors (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Tue, 28 Mar 2006 23:07:00 +0100
There's no such thing as literally "non" inductive, so the question then becomes: how low is it really? Or perhaps: how much does it matter for each particular application? -- 73 from Ian GM3SEK 'In
/archives//html/Amps/2006-03/msg00714.html (10,218 bytes)

93. Re: [Amps] Need some 220K 2 watt carbon resistors (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Wed, 29 Mar 2006 21:51:30 +0100
Scrape off enough of the paint/cement/enamel to be able to count the number of turns (n). Measure the diameter (d) and length (b), and then plug the numbers into the usual formula: L = d^2*n^2/(18*d
/archives//html/Amps/2006-03/msg00759.html (10,959 bytes)

94. Re: [Amps] [Moon-net] 4CX250B in P-P 2m? (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Fri, 31 Mar 2006 19:43:33 +0100
A kilowatt output can just about be done: increase the B+ to 2.5kV (on-load), use a big blower, forget any pretence about linearity, bias the tubes into class B or C to give them a rest on key-up, th
/archives//html/Amps/2006-03/msg00806.html (8,564 bytes)

95. Re: [Amps] The ongoing 4CX250B verbage! (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Tue, 4 Apr 2006 13:58:24 +0100
That seems quite reasonable, because the tubes are only being driven to 275-300W output per tube. Turning to 4CX250Rs, GW4FRX measured 3rd-order IMD of -30dB below either tone for a pair of 250Rs dri
/archives//html/Amps/2006-04/msg00040.html (9,693 bytes)

96. Re: [Amps] The ongoing 4CX250B verbage! (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Tue, 4 Apr 2006 20:40:27 +0100
Nice one, Steve :-) My apologies for rekindling this Holy War. I don't care which convention people use, so long as they say what they're doing. The objectionable practice is to add 6dB with the sole
/archives//html/Amps/2006-04/msg00059.html (8,562 bytes)

97. Re: [Amps] 4CX250B and data sheets in general. (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Tue, 4 Apr 2006 21:15:53 +0100
wrote: This particular data sheet did exactly what you say: it specified the operating conditions, the PEP output and the levels of IMD to be expected. In doing so, it implied that the company endors
/archives//html/Amps/2006-04/msg00060.html (9,666 bytes)

98. Re: [Amps] Chimney materials - Loss or not TSPA (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Fri, 14 Apr 2006 20:50:04 +0100
I think he microwave oven test does provide useful information - within its limitations, of course. If you test similar samples of various materials at the same time (relying on the turntable or mode
/archives//html/Amps/2006-04/msg00259.html (10,208 bytes)

99. Re: [Amps] New Elecraft Amps (GS35B sockets?) (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Thu, 27 Apr 2006 08:29:05 +0100
The method of cooling by blowing the cold air in above the chassis can be made to work perfectly well - indeed, it is the *normal* method of cooling in many VHF/UHF amplifiers, both amateur and comme
/archives//html/Amps/2006-04/msg00397.html (12,766 bytes)

100. Re: [Amps] Looking for amp design useing 2- 4CX250b tubes (score: 1)
Author: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Sat, 6 May 2006 18:07:09 +0100
There is an excellent design by W2GN (SK) at: http://www.radiowrench.com/sonic/so02197.html You can download the PDF from there, or maybe more easily from: http://www.newsvhf.com/w2gn.html -- 73 from
/archives//html/Amps/2006-05/msg00024.html (7,402 bytes)


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