RE: LF: Re: U.S. VLF License WH2XBA

[Bob Raide <rjraide@hotmail.com>]

Alan;
I am noticing exactly that-groundwave not that good at 29 kHz.  Much better at 137 or even 74.  Just got report from Kansas where I always put good daytime sigs in on 137-74.  Got lot to learn about this VLF stuff-Bob
 

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From: alan.melia@btinternet.com
To: rsgb_lf_group@blacksheep.org
Date: Sat, 1 Mar 2014 21:15:41 +0000
Subject: Re: LF: Re: U.S. VLF License WH2XBA

Hi Bob if you mean "skywave" or ionospheric returns? that occurs day and night at LF and VLF the skywave is weaker in daytime at LF due to a portion of absorbing D-lyer below the apparent reflection height, also at VLF but less so. At the powers we use the ground wave probably does not go very far. I think the two are about the same strength at around 400miles then the skywave predominates. It may be less with amateir antennas because a lot more of the signal is lanuched at higher angles that would be the case for big antenna on Mil sites.

 

I think there is some confusion about VLF being "all groundwave". Many of these ideas were formed in the days before Heaviside and Appleton. Ionospheric return is fom the D-layer in daytime (with some absorption) and by the lower E-layer at night.

 

Paul Nicholson has front-ended some Mil propagtion software for VLF called LWPC  you can tell its the "real stuff it was written in Fortran :-))

Single shot strengths are calculated for the date and time entered so you can see diurnal effects. I have not tried it at very short range but it certainly models he day-night transition quite well

It is at http://abelian.org/lwpc/

 

Best Wishes for Good VLF DX

Alan

G3NYK

 

----- Original Message -----

From: Bob Raide

To: rsgb_lf_group@blacksheep.org

Sent: Saturday, March 01, 2014 8:14 PM

Subject: RE: LF: Re: U.S. VLF License WH2XBA

Alan;
Will the "skip" be at night like all higher freqs?  And the later [early morning] might be best?   Bob
 

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From: alan.melia@btinternet.com
To: rsgb_lf_group@blacksheep.org
Date: Sat, 1 Mar 2014 19:13:49 +0000
Subject: Re: LF: Re: U.S. VLF License WH2XBA

Hi Bob

Almost certainly there will be "skywave" At 30 miles the ground and skywaves may be out of phase and near the same strength. We can detect two hop in the UK at 70miles range on 19.6kHz Anthorn. Not only that your short antenna will throw quite a bit skywards.....it cant get through the ionosphere so it gotta come back :-))

 

Alan

 

 

----- Original Message -----

From: Bob Raide

To: rsgb_lf_group@blacksheep.org

Sent: Saturday, March 01, 2014 6:22 PM

Subject: RE: LF: Re: U.S. VLF License WH2XBA

Alan;
Do you think there will be nights of skywave propagation as low as 30 kHz?  Without it I don't see my .1 w ERP going anywhere close.
BTW;
I have a BC engineer friend about 30 miles from here.  He could barely hear my fundamental signal and said 60 kHz is S9 at his QTH.
I measured my second harmonic-appears about -60 db down- at 58.998.  
I will have a 60 kHz clock tomorrow to seen if any cal trouble right here at transmitter location-Bob
 

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From: alan.melia@btinternet.com
To: rsgb_lf_group@blacksheep.org
Date: Sat, 1 Mar 2014 18:12:48 +0000
Subject: Re: LF: Re: U.S. VLF License WH2XBA

Hi Warren I think the 70kHz "boundary" is just the point at which the Earth-Ionosphere waveguide supports so many different modes that the modelling becomes difficult and the ray path is as effective.  Even this transition is fuzzy and is often quoted as low as 50kHz.

 

It may be of interest that Paul Nicholson has put a web front end to the LWPC propagation code

http://abelian.org/lwpc/  This gives reasonable results up to around 45kHz. I have done some tests on it and it gives quite sensible answers.

 

Alan

G3NYK

----- Original Message -----

From: Warren Ziegler

To: rsgb_lf_group

Sent: Saturday, March 01, 2014 3:54 PM

Subject: Re: LF: Re: U.S. VLF License WH2XBA

Hi Alan,

      I agree, there was nothing that I could find that indicated that there would be a problem at 30kHz. I even checked with a well known vlf expert who has done design work for some of the BIG military vlf systems. Somewhere around 70kHz there is a transitional area between waveguide modes applicable at vlf and ray-tracing which is applicable at higher frequencies. The increased number of modes above 70kHz I believe explains the deep fading there as the modes constructively and destructively interfere.

   However, it didn't hurt to ask for the additional frequencies as Dex was able to use an existing loading coil to get on 45kHz within hours of the license being issued!

73 Warren K2ORS

On Sat, Mar 1, 2014 at 10:40 AM, Alan Melia <alan.melia@btinternet.com> wrote:

Hi Warren I cant see30kHz being particularly different for propgation in that part of the spectrum. I can see 2nd harmonic trashing WWVB clock synchronisation over a substantial area though, bearing in mind the receivers are very simple.........and most only try to sync around midnight.

 

Alan

G3NYK.

----- Original Message -----

From: Warren Ziegler

To: rsgb_lf_group

Sent: Saturday, March 01, 2014 3:17 PM

Subject: LF: U.S. VLF License WH2XBA

Hello the list,

    Several questions have come up concerning the WH2XBA grant and I thought I might address them here.  Bob W2ZM contacted me about applying for a grant at the top end of the vlf range (just below 30kHz).

The thought was that the high end of vlf would be a bit less challenging than the low end below 9kHz (which is unregulated).

    Some of the usual suspects expressed interest so they were added to the application. Also Jim AA5BW - Jim and I have a mutual friend through work - Jim is highly capable and  technical and has multiple sites throughout the country.   There was some concern that the frequencies around 30kHz were unoccupied due to propagation reasons and some thought it might be good to go a bit higher, hence the 27-59kHz range, leaving clearance for WWVB at the top end. 

     The license is for 5W ERP, 27-59kHz, CW and every data mode that I could think of.

    The application was filed on January 29 and the license issued on February 27 - this was despite some Federal Holidays and closings due to blizzards!  So I suspect that it didn't raise too many questions.

     The stations are:

WH2XBA/1     Bob W2ZM

WH2XBA/2   Warren K2ORS

WH2XBA/3     Jay W1VD

WH2XBA/4     Dex  W4DEX

WH2XBA/5   Laurence KL1L 

WH2XBA/6 /7 /8 etc etc James Plesa AA5BW

 

WH2XBA Grant Attached.

73 Warren K2ORS

--
73 Warren K2ORS
                WD2XGJ
                WD2XSH/23
                WE2XEB/2
                WE2XGR/1

                WG2XRS/1

                WH2XBA/2

 

--
73 Warren K2ORS
                WD2XGJ
                WD2XSH/23
                WE2XEB/2
                WE2XGR/1