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101. Re: [Amps] Filament monitoring - LOOKING FOR ELMER (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Sat, 09 Apr 2016 16:06:01 +0100; Correction, sorry. Opamp U2A adds x2.5 gain so nominal current in the heaters will give ~+5V at FIL_MON. D25 prevents it going -ve and D24 clamps the output at 5V, both presumably to protect whatever; /archives//html/Amps/2016-04/msg00016.html (9,231 bytes)
102. Re: [Amps] new high power transistor announced (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Fri, 06 May 2016 21:53:58 +0100; It's been a game of musical chairs. The old NXP product line (BLF... etc.) has been floated off separately as Ampleon, centred on the original Philips RF factory at Nijmegan. They have some new produ; /archives//html/Amps/2016-05/msg00006.html (8,313 bytes)
103. Re: [Amps] Ldmos heat spreaders (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Mon, 22 Aug 2016 07:44:16 +0100; I do agree on the interfaces being extremely important, and the most important one is that between the FET and the spreader. Soldering the FET to the spreader is essential when the application has h; /archives//html/Amps/2016-08/msg00068.html (8,864 bytes)
104. Re: [Amps] LDMOS HEAT SPREADERS (score: 1): Author: Steve <g8gsq72@gmail.com>; Date: Tue, 30 Aug 2016 15:53:41 +0100; Can't see why not with a bit of effort and ingenuity, and looks well worth the effort. The same people list 'liquid chill plates' under the 'heat sinks' category. These look remarkably similar to one; /archives//html/Amps/2016-08/msg00076.html (8,786 bytes)
105. Re: [Amps] LDMOS HEAT SPREADERS (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Wed, 31 Aug 2016 22:33:05 +0100; I guess the factory probably has a supply of chilled water at pressure to make life easier. If I've got my sums right, with perfect heat transfer, around 240ml/min should be sufficient. OK, in realit; /archives//html/Amps/2016-09/msg00000.html (8,601 bytes)
106. Re: [Amps] RF voltage on VHF strip line (score: 1): Author: Steve <g8gsq72@gmail.com>; Date: Tue, 1 Nov 2016 11:06:26 +0000; What effects/damage are you seeing? Does it always happen in the same place? Can you run the amp with reduced plate voltage? That might show up whether it's a marginal effect where rf on top of dc is; /archives//html/Amps/2016-11/msg00008.html (9,176 bytes)
107. Re: [Amps] MLA2500 issue (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Tue, 15 Nov 2016 07:51:02 +0000; What happens to the HV, grid current and plate current during these changes? Steve Hi All, I'm no amp expert, but have owned an MLA2500 for close to 3 decades. I've repaired it a few times (all new c; /archives//html/Amps/2016-11/msg00048.html (8,602 bytes)
108. [Amps] ENI21 transistors (score: 1): Author: Steve <g8gsq72@gmail.com>; Date: Fri, 9 Dec 2016 15:44:42 +0000; Most ENI transistors were standard product line parts from the main manufacturers, sometimes tested to slightly different specs., or using ENI fixture, but always marked with a custom part number. Wh; /archives//html/Amps/2016-12/msg00218.html (7,131 bytes)
109. Re: [Amps] SS amps and auto-tune. Is it even necessary? (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Sun, 11 Dec 2016 18:59:16 +0000; I think Manfred has a point - where the harmonics aren't going into a load and are being 'reflected' by the harmonic filter, I think the phase between fundamental and harmonics matters. The right rel; /archives//html/Amps/2016-12/msg00269.html (10,030 bytes)
110. Re: [Amps] Time to back up- SS and autotune (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Sat, 17 Dec 2016 22:57:44 +0000; I believe, in transmitters of this type, that the modules aren't combined in the same way we're used to in the likes of Quadra, PW-1 or SPE type amps - in the AM txs I think it's more like the module; /archives//html/Amps/2016-12/msg00406.html (8,830 bytes)
111. Re: [Amps] TRANS WORLD TW500A-RM (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Wed, 21 Dec 2016 21:59:42 +0000; I'm sure that somewhere I have the user manual for the TW500 mobile version. If I can find it and get any spare time over the holiday I'll run it through the scanner. In answer to Emile's original qu; /archives//html/Amps/2016-12/msg00435.html (9,419 bytes)
112. Re: [Amps] TRANS WORLD TW500A-RM (score: 1): Author: Steve <g8gsq72@gmail.com>; Date: Thu, 22 Dec 2016 12:13:13 +0000; You're absolutely right, Dave. I found my manual which is for TW500M not TW500A. The TW500M is a 12V mobile amp and appears to be identical to Metron 1000B apart from the front panel badge. My apolog; /archives//html/Amps/2016-12/msg00438.html (9,506 bytes)
113. Re: [Amps] TRANS WORLD TW500A-RM (score: 1): Author: Steve <g8gsq72@gmail.com>; Date: Fri, 23 Dec 2016 11:33:36 +0000; As you were - a direct email from Emile says that his TW500A uses 12V transistors and is not simply half a TW1000A. Steve I found a manual for Metron 100B on the BAMA site - apart from the brand name; /archives//html/Amps/2016-12/msg00439.html (9,949 bytes)
114. Re: [Amps] FCC Denies Expert Linears' Request for Waiver of 15 dB Rule; (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Mon, 2 Jan 2017 10:36:41 +0000; For most of the 40odd years I've had my licence, it's given me a unique privilege: that of being able to operate a transmitter which hasn't been checked, tested or type approved by someone else. No o; /archives//html/Amps/2017-01/msg00010.html (8,270 bytes)
115. [Amps] Transworld TW500M manual (score: 1): Author: Steve <g8gsq72@gmail.com>; Date: Tue, 3 Jan 2017 16:16:12 +0000; I've now scanned my copy of the handbook. I've emailed it to BAMA so hopefully it will be available generally soon, but in the meantime email me off list if anyone wants a copy. Regarding the power t; /archives//html/Amps/2017-01/msg00040.html (7,007 bytes)
116. Re: [Amps] Diagnosing relay problem (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Sun, 8 Jan 2017 16:10:23 +0000; If there's enough cable length between the relays in the rx path, a TDR might do it. I feel sure there should be a way using a capacitance meter, but I haven't stopped to figure out how yet. Steve I; /archives//html/Amps/2017-01/msg00181.html (8,379 bytes)
117. Re: [Amps] 220 MHz segment (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Wed, 11 Jan 2017 07:56:05 +0000; Most of the ACSSB junk has been ripped out. I did some work for the UK company which came up with the original system which, I think, EFJ marketed in the US. 20odd years ago 5kHz channel spacing and; /archives//html/Amps/2017-01/msg00226.html (6,826 bytes)
118. Re: [Amps] rich Richard - tiny antenna (score: 1): Author: Steve <g8gsq72@gmail.com>; Date: Mon, 10 Apr 2017 15:36:45 +0100; The -30dB figure in the report is dB reference pep. Take 6dB off to get dBc so it's -24dBc. That's lousy. Steve This is not correct. More like -30 dB for the new K3S and -27 dB for the older K3, acco; /archives//html/Amps/2017-04/msg00047.html (8,378 bytes)
119. Re: [Amps] 144 MHz GS35B input circuit (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Mon, 1 May 2017 08:09:50 +0100; That sounds totally wrong to me. The rf needs to go onto the common point of the cathode and filament (or heater as I prefer to call it where there's a separate cathode). As long as the heater supply; /archives//html/Amps/2017-05/msg00005.html (8,792 bytes)
120. Re: [Amps] High voltage MOSFETs (score: 1): Author: Steve Thompson <g8gsq72@gmail.com>; Date: Wed, 3 May 2017 23:09:35 +0100; I think most of these are products inherited when they took over APT. There's a number of app notes to go with them - they were originally designed for narrow band saturated cw use and one common the; /archives//html/Amps/2017-05/msg00046.html (7,798 bytes)

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