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61. Re: LF: Survival (score: 1)

Author: "Andy Talbot" <andy.g4jnt@googlemail.com>

Date: Tue, 6 May 2008 13:41:40 +0100

And I thought the dinosaurs died out 650 million years ago :-) Andy G4JNT (Never used a valve in my life. Dislike morse but forced to use it occasionally on microwave bands, and find its a good a cod

/rsgb_lf_group-archives/html/rsgb_lf_group/2008-05/msg00013.html (11,731 bytes)

62. Re: LF: Re: Loran C (score: 1)

Author: "Andy Talbot" <andy.g4jnt@googlemail.com>

Date: Thu, 19 Jun 2008 18:28:56 +0100

Good - I'm glad to know the telecomms opeators have thought about the vulnerabilities inherent with putting all their eggs into the GPS timing basket. I had been told - clearly from a not too informe

/rsgb_lf_group-archives/html/rsgb_lf_group/2008-06/msg00041.html (13,413 bytes)

63. LF: VE2ZAZ GPSDO findings (score: 1)

Author: "Andy Talbot" <andy.g4jnt@googlemail.com>

Date: Mon, 16 Jun 2008 20:17:14 +0100

Having now completed and mostly tested two VE2ZAZ GPS Controlled oscvillators, I can say I'm rather more than quite impressed with what can be achieved. Both GPSDOs were built using good quality sing

/rsgb_lf_group-archives/html/rsgb_lf_group/2008-06/msg00088.html (13,349 bytes)

64. Re: LF: Re: Loran C (score: 1)

Author: "Andy Talbot" <andy.g4jnt@googlemail.com>

Date: Thu, 19 Jun 2008 21:43:22 +0100

The whole over-air interface for the mobile phone system has to be locked - the frame structure in GSM is critical to microseconds, and has to be synchronised between all base stations. I believe 3G

/rsgb_lf_group-archives/html/rsgb_lf_group/2008-06/msg00111.html (12,644 bytes)

65. Re: LF: Re: Loran C (score: 1)

Author: "Andy Talbot" <andy.g4jnt@googlemail.com>

Date: Thu, 19 Jun 2008 08:41:19 +0100

The article has a very good point to make about GPS jamming though. I think its probably the first time I've seen it talked about in the open-press. Our telecomms infrastructure now is so critically

/rsgb_lf_group-archives/html/rsgb_lf_group/2008-06/msg00127.html (12,739 bytes)

66. Re: LF: Rad Com / critical mass etc (score: 1)

Author: "Andy Talbot" <andy.g4jnt@googlemail.com>

Date: Fri, 18 Jul 2008 19:55:47 +0000

That's because no one sends anything in !!!!!!!!!!!!!! As I said in a previous posting a few months ago to one of the many groups (microwaves, probably) - its positive feedback. People see reduced te

/rsgb_lf_group-archives/html/rsgb_lf_group/2008-07/msg00002.html (11,671 bytes)

67. LF: Loop Conundrum (score: 1)

Author: "Andy Talbot" <andy.g4jnt@googlemail.com>

Date: Mon, 21 Jul 2008 12:29:33 +0100

Was pondering this while out walking the other day, and couldn't come to a satisfactory conclusion either way... A small magnetic loop mounted vertically has a defined radiation resistance that is a

/rsgb_lf_group-archives/html/rsgb_lf_group/2008-07/msg00026.html (11,550 bytes)

68. Re: LF: satellites/RadCom (score: 1)

Author: "Andy Talbot" <andy.g4jnt@googlemail.com>

Date: Thu, 17 Jul 2008 11:24:06 +0100

Two pijnts... 1) Satellites Having just joined Amsat (because I felt I 'ought' to) I'm less than impressed with a) Oscar News which has had no technical content in the two issues so far received, and

/rsgb_lf_group-archives/html/rsgb_lf_group/2008-07/msg00038.html (12,665 bytes)

69. Re: LF: Re: LF RadCom Articles (score: 1)

Author: "Andy Talbot" <andy.g4jnt@googlemail.com>

Date: Sun, 20 Jul 2008 20:05:45 +0000

Radcom redraw all diagrams anyway - and now with wiggly resistors. Theyt tend to leave the text alone unless there are glaring errors or bad English, so it looks as if you could be onto a winner. Giv

/rsgb_lf_group-archives/html/rsgb_lf_group/2008-07/msg00052.html (14,982 bytes)

70. Re: LF: satellites/RadCom (score: 1)

Author: "Andy Talbot" <andy.g4jnt@googlemail.com>

Date: Sun, 20 Jul 2008 18:52:58 +0100

Which big bang ? A few superpowers may have tested the occasional EMP weapon with 'interesting' findings, but no one ever deployed one - they all realised the potential for damaging thier own infrast

/rsgb_lf_group-archives/html/rsgb_lf_group/2008-07/msg00066.html (14,866 bytes)

71. Re: LF: Re: LF RadCom Articles (score: 1)

Author: "Andy Talbot" <andy.g4jnt@googlemail.com>

Date: Sun, 20 Jul 2008 18:44:02 +0100

btw. By LCL output stage, assume you mean a lowpass Tee network? Andy G4JNT www.scrbg.org/g4jnt design --

/rsgb_lf_group-archives/html/rsgb_lf_group/2008-07/msg00083.html (12,977 bytes)

72. LF: Loop conundrum (score: 1)

Author: "Andy Talbot" <andy.g4jnt@googlemail.com>

Date: Fri, 25 Jul 2008 08:49:37 +0100

Tnx for the replies on this. In the original post I'd forgotton that Chu-Harrington described a sphere just sufficient to enclose the antenna, so a pair od crossed loops would fit into the same size

/rsgb_lf_group-archives/html/rsgb_lf_group/2008-07/msg00118.html (10,968 bytes)

73. Re: LF: RADCOM (score: 1)

Author: "Andy Talbot" <andy.g4jnt@googlemail.com>

Date: Fri, 18 Jul 2008 15:06:15 +0100

EXcuse meThe only country that doesn't oficially use the Metric system is the USA, along with two tiny ones whose names don't come to mind. And look what not using it cost the Nasa space programme! I

/rsgb_lf_group-archives/html/rsgb_lf_group/2008-07/msg00130.html (12,268 bytes)

74. Re: LF: Rad Com / critical mass etc (score: 1)

Author: "Andy Talbot" <andy.g4jnt@googlemail.com>

Date: Sat, 19 Jul 2008 09:30:24 +0000

Not speculation, I've had several discussions with him on the subject, and my idea of Radcom going unstable had him quite amused. But it is a feedback situation, and as in all control systems, the wr

/rsgb_lf_group-archives/html/rsgb_lf_group/2008-07/msg00144.html (13,166 bytes)

75. Re: LF: new cw yahoo group (score: 1)

Author: "Andy Talbot" <andy.g4jnt@googlemail.com>

Date: Tue, 12 Aug 2008 11:13:00 +0100

Excellent. And if more people used computer generated morse for transmitting, the decoding software would be more reliable still. We don't want any of this hand sent, badly formatted stuff :-) Andy G

/rsgb_lf_group-archives/html/rsgb_lf_group/2008-08/msg00069.html (11,328 bytes)

76. Re: LF: new cw yahoo group (score: 1)

Author: "Andy Talbot" <andy.g4jnt@googlemail.com>

Date: Wed, 13 Aug 2008 07:57:16 +0100

Your dual tone proposal is an excellent idea but suffers from one major drawback for LF. Being a dual tone sysytem, it requires a linear transmitter. If you could adapt the scheme to a single tone on

/rsgb_lf_group-archives/html/rsgb_lf_group/2008-08/msg00165.html (17,580 bytes)

77. Re: LF: Re: 500KHz NoV (score: 1)

Author: "Andy Talbot" <andy.g4jnt@googlemail.com>

Date: Mon, 4 Aug 2008 19:57:45 +0100

That's going back a bit. Old-enough technology to keep Mal happy :-) -- Andy G4JNT www.scrbg.org/g4jnt

/rsgb_lf_group-archives/html/rsgb_lf_group/2008-08/msg00239.html (11,385 bytes)

78. Re: LF: Usefull BBC document , low frequency Ae design (score: 1)

Author: "Andy Talbot" <andy.g4jnt@googlemail.com>

Date: Tue, 18 Nov 2008 20:51:11 +0000

Looking at the list of BBC Publications ( http://www.bbc.co.uk/rd/pubs/whp/index101-120.shtml ) the author of this paper, R.H.M. Poole, has also written one on electrically short antennas; and on a f

/rsgb_lf_group-archives/html/rsgb_lf_group/2008-11/msg00275.html (12,153 bytes)

79. Re: LF: Re: 3C85/90 Toroids (score: 1)

Author: "Andy Talbot" <andy.g4jnt@googlemail.com>

Date: Thu, 20 Nov 2008 16:44:35 +0000

Yes that's correct. The Txxx is a size designation, -2 is iron powder mix 2, suited for MF to low HF. For SMPSU / LF transformers Siemens N80 material is a substitute for 3C85 / 3C90.(hope I've remem

/rsgb_lf_group-archives/html/rsgb_lf_group/2008-11/msg00607.html (13,530 bytes)

80. LF: E field active antennas (score: 1)

Author: "Andy Talbot" <andy.g4jnt@googlemail.com>

Date: Fri, 5 Dec 2008 16:22:56 +0000

Having just had to make an active antenna for HF (for gainful employment-type work, not Am. radio purposes. The commercially made one we've ordered is on five weeks delivery and it was needed before

/rsgb_lf_group-archives/html/rsgb_lf_group/2008-12/msg00150.html (11,361 bytes)