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61. [Amps] RE: Problems with Heath SB-220 (score: 74): Author: G3SEK at ifwtech.co.uk (Ian White, G3SEK); Date: Thu Jan 23 04:12:55 2003; Agreed... but so far we have been focusing on switching capacity. The other issue is the effect on T/R timing and RF arcing in the amp's antenna relay. The open-frame relays on most older amps are to; /archives//html/Amps/2003-01/msg00187.html (9,609 bytes)
62. [Amps] Reducing Ameritron AL-800H blower noise? (score: 74): Author: G3SEK at ifwtech.co.uk (Ian White, G3SEK); Date: Sun Jan 26 17:46:20 2003; [...] How do you know that? If there is a difference due to frequency, what is the physical reason for it? -- 73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB) Editor, 'The VHF/UHF DX Book'; /archives//html/Amps/2003-01/msg00230.html (8,004 bytes)
63. [Amps] Reducing Ameritron AL-800H blower noise? (score: 74): Author: G3SEK at ifwtech.co.uk (Ian White, G3SEK); Date: Mon Jan 27 05:35:40 2003; Thank you for the direct quote from EIMAC. From time to time it seems a good idea to separate what EIMAC said from your own opinions about what that implies. Also EIMAC notably do *not* say anything; /archives//html/Amps/2003-01/msg00236.html (10,647 bytes)
64. [Amps] Reducing Ameritron AL-800H blower noise? (score: 74): Author: G3SEK at ifwtech.co.uk (Ian White, G3SEK); Date: Tue Jan 28 16:12:19 2003; I tried to send this message yesterday... See below... Sorry, but none of that theory ties-in with what VHF/UHF amplifier users know about the same tubes. The grid "monopole" is heavily capacitively; /archives//html/Amps/2003-01/msg00271.html (14,033 bytes)
65. [Amps] Q: Chimneys for 3-500/4-400?? (score: 147): Author: Ian White, G3SEK" <g3sek@ifwtech.co.uk (Ian White, G3SEK); Date: Wed, 4 Dec 2002 00:03:36 +0000; [...] A while ago, I made some rough measurements on the 3-500Z in an SB-1000, using thermal-sensitive labels on the glass. That amp has a 6in Muffin-type fan blowing across the tube, with the air ou; /archives//html/Amps/2002-12/msg00054.html (9,216 bytes)
66. [Amps] Meter Shunts (score: 147): Author: Ian White, G3SEK" <g3sek@ifwtech.co.uk (Ian White, G3SEK); Date: Mon, 9 Dec 2002 12:00:03 +0000; Pretty close. Right values for the low-value resistors (which need to be power types), but the resistor in series with the meter is too high - your 1k has to include the meter's own internal resistan; /archives//html/Amps/2002-12/msg00154.html (10,519 bytes)
67. [Amps] re: Magic values for "Glitch" Resistors in HV Pwr Sply (score: 147): Author: Ian White, G3SEK" <g3sek@ifwtech.co.uk (Ian White, G3SEK); Date: Sun, 22 Dec 2002 19:56:01 +0000; Don't know where you might have read that, but it doesn't look like good advice, for two reasons... [This information comes from Eimac Bulletin #17 on 'Fault Protection', downloadable at: www.ifwtech; /archives//html/Amps/2002-12/msg00244.html (13,761 bytes)
68. [Amps] ICOM 756 PRO II or FT 1000 MP Field or Mk 5 ? (score: 147): Author: Ian White, G3SEK" <g3sek@ifwtech.co.uk (Ian White, G3SEK); Date: Tue, 24 Dec 2002 09:11:58 +0000; There's a head-to-head user review at: http://www.w8zr.com/markv/index.htm -- 73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB) Editor, 'The VHF/UHF DX Book' http://www.ifwtech.co.uk/g3sek; /archives//html/Amps/2002-12/msg00265.html (8,825 bytes)
69. [Amps] resistor (score: 147): Author: Ian White, G3SEK" <g3sek@ifwtech.co.uk (Ian White, G3SEK); Date: Tue, 24 Dec 2002 09:06:35 +0000; I've "seen" both of those, when providing remote diagnostics for people using my Triode Board without an effective surge resistor. In one VHF amp, the air-wound RF choke was completely crunched up by; /archives//html/Amps/2002-12/msg00266.html (7,953 bytes)
70. [Amps] FT-1000D Band Data Jack (score: 147): Author: Ian White, G3SEK" <g3sek@ifwtech.co.uk (Ian White, G3SEK); Date: Sat, 28 Dec 2002 14:56:43 +0000; There is no "special tab" - the connector has an ordinary metal shell. If you're desperate, you can poke wires straight into the socket, and use the empty shell from any metal DIN plug to operate the; /archives//html/Amps/2002-12/msg00312.html (7,216 bytes)
71. [Amps] Re: [Amps] various parasitic sources... chassis, tubes, etc... (score: 147): Author: Ian White, G3SEK" <g3sek@ifwtech.co.uk (Ian White, G3SEK); Date: Wed, 6 Nov 2002 14:32:28 +0000; The 8877 is well known as a *stable* tube for amplifiers at 50MHz and 144MHz. With the input and output both tuned to the same frequency, and typically 15-18dB of on-frequency gain, it's stable. If y; /archives//html/Amps/2002-11/msg00056.html (9,003 bytes)
72. [Amps] Re: [Amps] various parasitic sources... chassis, tubes, etc... (score: 147): Author: Ian White, G3SEK" <g3sek@ifwtech.co.uk (Ian White, G3SEK); Date: Wed, 6 Nov 2002 16:26:24 +0000; On the contrary, every VHF/UHF amp I can think of has at least one parasitic resonance. For example... 50MHz pi- or pi-l: parasitic resonance above the operating frequency, for exactly the same reaso; /archives//html/Amps/2002-11/msg00059.html (11,992 bytes)
73. [Amps] G8GSQ only (score: 147): Author: Ian White, G3SEK" <g3sek@ifwtech.co.uk (Ian White, G3SEK); Date: Sun, 10 Nov 2002 14:11:48 +0000; Sorry to have to use the list for this: Steve - I've been trying to e-mail you direct at the qsl.net address, with no success. -- 73 from Ian G3SEK; /archives//html/Amps/2002-11/msg00156.html (6,204 bytes)
74. [Amps] Re: 8877 dissp (score: 147): Author: Ian White, G3SEK" <g3sek@ifwtech.co.uk (Ian White, G3SEK); Date: Thu, 14 Nov 2002 07:51:46 +0000; To answer #2, it depends on the tube and the voltage reduction you have applied. Fortunately you can measure the recovery time - or the warm-up time from cold - by measuring the heater current. The h; /archives//html/Amps/2002-11/msg00221.html (8,828 bytes)
75. [Amps] Hot Switching (score: 147): Author: Ian White, G3SEK" <g3sek@ifwtech.co.uk (Ian White, G3SEK); Date: Fri, 15 Nov 2002 08:17:14 +0000; It depends on the combination of the transceiver, the amp and the voice. Basically it's a race against time between the transceiver and the amp. The amp gets its PTT from the transceiver, and it then; /archives//html/Amps/2002-11/msg00240.html (12,946 bytes)
76. [Amps] Output Safety Choke Value (score: 147): Author: Ian White, G3SEK" <g3sek@ifwtech.co.uk (Ian White, G3SEK); Date: Fri, 15 Nov 2002 10:28:56 +0000; Probably when TV doorknob caps were pushed beyond their limits. But it is a real risk - although the probability is low, the consequences of B+ voltage getting onto the antenna line could be very nas; /archives//html/Amps/2002-11/msg00243.html (9,308 bytes)
77. [Amps] Hot Switching (score: 147): Author: Ian White, G3SEK" <g3sek@ifwtech.co.uk (Ian White, G3SEK); Date: Fri, 15 Nov 2002 09:57:57 +0000; It seems to be a crossover from CB amps, via the "bricks" intended for amateur VHF-FM hand-helds that don't have a PTT output. But from there, RF-actuated switching seems to have trickled down into a; /archives//html/Amps/2002-11/msg00244.html (7,983 bytes)
78. [Amps] Hot Switching (score: 147): Author: Ian White, G3SEK" <g3sek@ifwtech.co.uk (Ian White, G3SEK); Date: Fri, 15 Nov 2002 16:45:39 +0000; The Ameritron and some Alphas use PIN diode QSK, which is very fast and will work fine... if the transceiver timings will let it. I wonder if that's due to the very long spring arm - probably the har; /archives//html/Amps/2002-11/msg00256.html (10,167 bytes)
79. [Amps] SB220 T/R relay substitution (score: 147): Author: Ian White, G3SEK" <g3sek@ifwtech.co.uk (Ian White, G3SEK); Date: Fri, 15 Nov 2002 16:25:35 +0000; On the 746 in all modes, it's about 12-14ms between the first key-down/PTT and the start of RF output. The HSEND/VSEND outputs on the DIN accessory sockets are the fastest for amp control, and they g; /archives//html/Amps/2002-11/msg00257.html (8,774 bytes)
80. [Amps] SB220 T/R relay substitution (score: 151): Author: Ian White, G3SEK" <g3sek@ifwtech.co.uk (Ian White, G3SEK); Date: Fri, 15 Nov 2002 23:31:36 +0000; Thanks - duly noted. Thanks for the offer - but if I did, I'd only be using a conventional short-persistence scope. Single-shot measurements can still be done using the storage devices at the back of; /archives//html/Amps/2002-11/msg00264.html (10,443 bytes)

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