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1. LF: LF Receivers (score: 1)
Author: "Andrew Talbot" <>
Date: 31 Jul 2001 14:17:36 +0100
I am now putting the finishing stages to a custom LF receiver, designed to be a useful accurate measurement tool as well as for operating. The design is optimised for narrow band and ultra narrow-ban
/rsgb_lf_group-archives/html/rsgb_lf_group/2001-07/msg00006.html (12,890 bytes)

2. LF: Re: Amateur VLF DX (score: 1)
Author: "Andrew Talbot" <>
Date: 24 Jul 2001 09:39:27 +0100
The "earth loop" antennas have their adherents, and seem appealing because of the potentially large size possible. The simple radiation resistance formulae suggest that loops should always lose out c
/rsgb_lf_group-archives/html/rsgb_lf_group/2001-07/msg00043.html (10,360 bytes)

3. LF: RE: 60 khz (score: 1)
Author: "Andrew Talbot" <>
Date: 19 Jul 2001 08:46:27 +0100
It is only off for maintenance. They usually fire it up for a few hours during the night to resynchronise clocks during these annual antenna cleaning sessions. But not last night obviously - my MSF c
/rsgb_lf_group-archives/html/rsgb_lf_group/2001-07/msg00076.html (9,255 bytes)

4. LF: ELF Antennas - ground loops tested. (score: 1)
Author: "Andrew Talbot" <>
Date: 17 Jul 2001 14:51:59 +0100
I did hear from a non attributable source in the academic world that at one time there was a proposal in this country to use the third rail of the railway network as an antenna for ELF/ULF communicat
/rsgb_lf_group-archives/html/rsgb_lf_group/2001-07/msg00095.html (10,951 bytes)

5. LF: Re: Near field of 9kHz antenna IV (score: 1)
Author: "Andrew Talbot" <>
Date: 16 Jul 2001 09:43:42 +0100
For our garden sized antennas I think that resonating a wire is completely impractical at these frequencies. What I intend looking at, (if a 9kHz NoV ever happens :-( is something like a ground loop.
/rsgb_lf_group-archives/html/rsgb_lf_group/2001-07/msg00101.html (11,296 bytes)

6. LF: RE: Near field of 9kHz antenna II (score: 1)
Author: "Andrew Talbot" <>
Date: 13 Jul 2001 15:52:55 +0100
Obviously not 1/R^6 roll off then !!! Looking at the figures for 1km and 2km it appears to be more like 1/R^2 which is the rate of the radiation field decay - surely the H field should fall off faste
/rsgb_lf_group-archives/html/rsgb_lf_group/2001-07/msg00121.html (8,950 bytes)

7. LF: RE: Fw: Near field of 9kHz antenna (score: 1)
Author: "Andrew Talbot" <>
Date: 13 Jul 2001 15:04:19 +0100
Looks very much like like 1/R^3 fall off - just as the equations predict. I seem to recall the magnetic field falls off even faster - 1/R^6 sound familiar. Looks as if allocations at 9kHz could be a
/rsgb_lf_group-archives/html/rsgb_lf_group/2001-07/msg00124.html (9,578 bytes)

8. LF: RE: Re: LF/Hyper test (score: 1)
Author: "Andrew Talbot" <>
Date: 12 Jul 2001 16:10:37 +0100
But they are not radiating it though, just compressing a lot of hot air. Unless some of the grain orientated, directional, oxgen free copper cables the Hi-Fi buffs claim are necessary have some magic
/rsgb_lf_group-archives/html/rsgb_lf_group/2001-07/msg00134.html (9,232 bytes)

9. RE: LF: LF/Hyper test (score: 1)
Author: "Andrew Talbot" <>
Date: 12 Jul 2001 11:06:34 +0100
The far field of a radiated signal, where the reactive E and H fields can be safely ignored in propagation loss measurements, occurs at approximately lambda / 2.pi At this frequency, with a wavelengt
/rsgb_lf_group-archives/html/rsgb_lf_group/2001-07/msg00137.html (12,175 bytes)

10. LF: RE: Re. Net access on power lines etc. (score: 1)
Author: "Andrew Talbot" <>
Date: 4 Jul 2001 09:57:55 +0100
Do you read Dave Lauder's EMC section in RadCom ?- it is often mentioned in there. RSGB were instrumental is setting up the expert group that defined the MPT1570 level for 9kHz to 150kHz. Unfortunate
/rsgb_lf_group-archives/html/rsgb_lf_group/2001-07/msg00187.html (10,896 bytes)

11. LF: RE: Re: More on lightning (score: 1)
Author: "Andrew Talbot" <>
Date: 3 Jul 2001 09:03:51 +0100
(most UK citizens dont know how big a metre is anyway). I certainly don't think that is true. Metric has been taught in schools since at least 1969 (was in primary school when it became compulsory) a
/rsgb_lf_group-archives/html/rsgb_lf_group/2001-07/msg00203.html (9,031 bytes)

12. LF: Voyez le Brick (Off Topic) (score: 1)
Author: "Andrew Talbot" <>
Date: 17 Aug 2001 15:46:41 +0100
A query resulting from a typical Friday afternoon conversation... In the English language there is a phrase useful for testing things such as typewriters, that includes every letter of the alphabet a
/rsgb_lf_group-archives/html/rsgb_lf_group/2001-08/msg00098.html (9,578 bytes)

13. RE: LF: Radiated power at PA0SE (score: 1)
Author: "Andrew Talbot" <>
Date: 14 Aug 2001 16:11:22 +0100
...................... I found a FS of 370 microvolt/metre. From this follows an impressive radiated power (EIRP) of 52 milliwatt. I guess). what program did you use ? You don't need a programme, jus
/rsgb_lf_group-archives/html/rsgb_lf_group/2001-08/msg00117.html (10,260 bytes)

14. LF: RE: <TECH> RA1792 (score: 1)
Author: "Andrew Talbot" <>
Date: 6 Aug 2001 09:30:47 +0100
All the RA1792s I have seen (admittedly all of the same vintage, manufactured within a couple of years of 1981) use a 455kHz 2nd IF. But since they also only have 10Hz steps there is obviously a late
/rsgb_lf_group-archives/html/rsgb_lf_group/2001-08/msg00166.html (9,755 bytes)

15. LF: RE: The CFA Antenna (again...) (score: 1)
Author: "Andrew Talbot" <>
Date: 2 Aug 2001 08:32:44 +0100
Yes. That is exactly what Maxwell stated and Hertz demonstrated 10 years later (I've just been re-reading a book on basic Electromagnetism). One field is generated from the other as soon as its value
/rsgb_lf_group-archives/html/rsgb_lf_group/2001-08/msg00193.html (10,156 bytes)

16. LF: RE: Re: SV: Re: SV: LF Receivers (score: 1)
Author: "Andrew Talbot" <>
Date: 1 Aug 2001 13:36:53 +0100
The PTC crystal heater may be one of the reasons for your sucess in pulling it so far. Most crystals are designed for nominal 20 deg operation, and if you heat them up the frequency drops. These crys
/rsgb_lf_group-archives/html/rsgb_lf_group/2001-08/msg00196.html (10,084 bytes)

17. LF: RE: SV: LF Receivers (score: 1)
Author: "Andrew Talbot" <>
Date: 1 Aug 2001 11:55:06 +0100
What an elegant solution ! For a signal generator as a piece of test equipment its ideal ! Although for my purposes in a receiver, exact frequency increments are not necessary provided the exact valu
/rsgb_lf_group-archives/html/rsgb_lf_group/2001-08/msg00199.html (9,455 bytes)

18. LF: LF Receivers (score: 1)
Author: "Andrew Talbot" <>
Date: 1 Aug 2001 09:25:44 +0100
But isn't the accuracy and stability of a cheap colour subcarrier xtal, pulled more than 100ppm from its normal operating point, going to swamp the values you derive from the 'nice' numbers generated
/rsgb_lf_group-archives/html/rsgb_lf_group/2001-08/msg00203.html (9,744 bytes)

19. LF: LF Receivers (score: 1)
Author: "Andrew Talbot" <>
Date: 1 Aug 2001 08:40:35 +0100
The BFO at 456kHz is derived by extracting the 57th harmonic of the 10MHz divided down to 8kHz. This was actually extremely simple and the most satisfying part of the breadboarding process to get goi
/rsgb_lf_group-archives/html/rsgb_lf_group/2001-08/msg00204.html (10,681 bytes)

20. LF: RE: Doppler effect. (score: 1)
Author: "Andrew Talbot" <>
Date: 26 Sep 2001 08:22:49 +0100
The rate of recombination of the E (?) layer causing the height to change at dusk / dawn will move at this sort of rate. I did see Doppler shifts, although not perhaps quite as great as this, on the
/rsgb_lf_group-archives/html/rsgb_lf_group/2001-09/msg00050.html (11,171 bytes)


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