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1. [Amps] Re: 10dB and propagation (score: 1)
Author: "David Lisney" <g0fvt@hotmail.com>
Date: Wed, 9 Feb 2005 18:50:54 -0000
I think this thread has some interesting twists without going into witchcraft. The standard practice of using switched attenuators and a measuring receiver is commonly used in various EMC measurement
/archives//html/Amps/2005-02/msg00344.html (31,439 bytes)

2. Re: [Amps] Tetrodes (Ian White GM3SEK) (score: 1)
Author: "David Lisney" <g0fvt@hotmail.com>
Date: Wed, 13 Jul 2005 16:55:36 +0100
Hi, my own little tetrode amplifier uses a conduction cooled version of the 4CX250, the CCS1, my screen supply is merely a pair of BU208 television transistors, one configured as a constant current s
/archives//html/Amps/2005-07/msg00147.html (7,572 bytes)

3. Re: [Amps] Marking Tubes (score: 1)
Author: "David Lisney" <g0fvt@hotmail.com>
Date: Sun, 17 Jul 2005 09:31:45 +0100
Hi, here in the UK it used to be possible to get kits to security mark the glass in car windows, maybe the kits are still available, may be a reasonable approach for your 3-500s, though not sure of t
/archives//html/Amps/2005-07/msg00186.html (6,405 bytes)

4. Re: [Amps] 4CX250 bases (David Kirkby) (score: 1)
Author: "David Lisney" <g0fvt@hotmail.com>
Date: Fri, 22 Jul 2005 20:19:59 +0100
Hi, just to confirm that like another contributor the base in my wee CCS1 amplifier is an "air system" one, I used a small brushless fan to cool the valve base area and to get a wee bit of airflow th
/archives//html/Amps/2005-07/msg00263.html (7,335 bytes)

5. Re: [Amps] 4CX250 bases (David Kirkby) (score: 1)
Author: "David Lisney" <g0fvt@hotmail.com>
Date: Sat, 23 Jul 2005 12:39:38 +0100
Hi, just to clarify the fan is not in the RF field, it pressurises the lower chassis of the amplifier and air then enters vents of grid compartment, then through base of valve to vaguely stir up the
/archives//html/Amps/2005-07/msg00270.html (7,338 bytes)

6. Re: [Amps] Fraudulent email to amps posters (score: 1)
Author: "David Lisney" <g0fvt@hotmail.com>
Date: Sat, 13 Aug 2005 15:49:17 +0100
Hi, I have received some spams with address probably trawled from here, the usual fake Ebay and Paypal correspondence with links to faked pages. Often you can find that the servers are owned by legit
/archives//html/Amps/2005-08/msg00462.html (9,682 bytes)

7. Re: [Amps] Parasitic Oscillation (score: 1)
Author: "David Lisney" <g0fvt@hotmail.com>
Date: Wed, 17 Aug 2005 20:06:33 +0100
73 de David _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
/archives//html/Amps/2005-08/msg00572.html (7,128 bytes)

8. Re: [Amps] Screen Supply for 4CX250 series (score: 1)
Author: "David Lisney" <g0fvt@hotmail.com>
Date: Sun, 11 Sep 2005 20:01:12 +0100
Hi, a couple of people emailed me off list for the circuit diagram of my transistor stabilised screen supply, sorry I had a hard-drive failure (how do they possibly claim such amazing MTBFs) if those
/archives//html/Amps/2005-09/msg00093.html (6,830 bytes)

9. Re: [Amps] PC power supplies in series (score: 1)
Author: "David Lisney" <g0fvt@hotmail.com>
Date: Sat, 3 Jun 2006 23:02:09 +0100
Although I have not tried PC power supplies in series I have in the past used a pair of 5v 40a switchmodes in series, I modified both to give about 7v out in order to end up with approximately 13.8v
/archives//html/Amps/2006-06/msg00067.html (8,645 bytes)

10. Re: [Amps] Mains Isolation Transformer (score: 1)
Author: "David Lisney" <g0fvt@hotmail.com>
Date: Sat, 1 Jul 2006 18:34:33 +0100
A point was made that the shack earth should not be part of the aerial, this seems commendable common sense, however in a typical situation (like mine) I have an HF transceiver which has it mains saf
/archives//html/Amps/2006-07/msg00018.html (8,594 bytes)

11. Re: [Amps] 70MHz transistor PA, schematics?? (score: 1)
Author: "David Lisney" <g0fvt@hotmail.com>
Date: Sun, 2 Jul 2006 13:27:00 +0100
Hi, at work I maintain a number of Low-Band (70Mhzish) systems, one of which runs a Storno exciter at about 15w into a 100w Kathrein linear amplifier. These are on continous transmit 24/7, last year
/archives//html/Amps/2006-07/msg00043.html (35,447 bytes)

12. Re: [Amps] Bandwidth (score: 1)
Author: "David Lisney" <g0fvt@hotmail.com>
Date: Tue, 4 Jul 2006 06:33:56 +0100
Hi, sometimes I think it can be interesting to see in practice what a transmitted product is like and whether it is troublesome... Some time ago I measured the spectral output of a Mk1 FT690 (a 6m al
/archives//html/Amps/2006-07/msg00164.html (7,438 bytes)

13. Re: [Amps] 8 pin balanced mixer (score: 1)
Author: "David Lisney" <g0fvt@hotmail.com>
Date: Fri, 14 Jul 2006 20:16:15 +0100
Sorry for the late contribution, someone asked about a possible replacement for one of these in an exciter, is the SBL1 what you are looking for? A passive double balanced mixer incorporating the two
/archives//html/Amps/2006-07/msg00389.html (6,575 bytes)

14. Re: [Amps] Switching Power Supplies (score: 1)
Author: "David Lisney" <g0fvt@hotmail.com>
Date: Fri, 14 Jul 2006 20:51:02 +0100
We had some issues with a UHF PMR base station being "heard" 50KHz away, due to residual ripple from a switch-mode. No time for experiments with it so it just got it's power source shifted to a linea
/archives//html/Amps/2006-07/msg00393.html (8,304 bytes)

15. Re: [Amps] HV transformers I want to series primary and parallel (score: 1)
Author: "David Lisney" <g0fvt@hotmail.com>
Date: Sat, 19 Aug 2006 14:11:00 +0100
I have operated two identical large transformers with their primaries in series and secondaries in parallel, in my case the secondaries were low voltage high current. It seemed an elegant way to get
/archives//html/Amps/2006-08/msg00559.html (6,796 bytes)

16. Re: [Amps] Coil Former (score: 1)
Author: "David Lisney" <g0fvt@hotmail.com>
Date: Sun, 8 Oct 2006 17:34:35 +0100
Hi Ian, I wonder if something like the ceramic former from an old electric fire element would behave for you, or for a larger diameter some old electric hairdriers had ceramic former too. Just random
/archives//html/Amps/2006-10/msg00054.html (7,333 bytes)

17. Re: [Amps] TL922-one tube dead (score: 1)
Author: "David Lisney" <g0fvt@hotmail.com>
Date: Sun, 10 Dec 2006 17:58:46 -0000
Hi, I have a TL922 but not yet seen the inside of it! However it is never a good idea IMHO to worry about spares before the extent to the damage is know. Since one tune is still lighting up and drawi
/archives//html/Amps/2006-12/msg00057.html (7,314 bytes)

18. Re: [Amps] TL922-one tube dead? (score: 1)
Author: "David Lisney" <g0fvt@hotmail.com>
Date: Sun, 10 Dec 2006 23:28:09 -0000
Sorry my previous posting assumed the heaters were in parallel, they are in series. _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/m
/archives//html/Amps/2006-12/msg00060.html (6,834 bytes)

19. Re: [Amps] How best to reduce filament voltage? (score: 1)
Author: "David Lisney" <g0fvt@hotmail.com>
Date: Fri, 2 Feb 2007 19:42:47 -0000
Hi, depending on the construction of your mains transformer sometimes it is feasible to slip a few turns of ordinary connecting wire round the bobbin as a "buck" winding. Obviously you will need to s
/archives//html/Amps/2007-02/msg00022.html (8,973 bytes)

20. Re: [Amps] General question on filament life (score: 1)
Author: "David Lisney" <g0fvt@hotmail.com>
Date: Sun, 11 Feb 2007 21:46:59 -0000
Hi, not much experience of this, however I once worked for a lamp manufacturer, there was a tendency for lamps to fail at switch on ( I believe we have all seen this). The cold resistance of a typica
/archives//html/Amps/2007-02/msg00193.html (28,740 bytes)


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