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500kHz


#1

Dear all

I have applied for a special permit to do some portable (SOTA) tests on 500kHz. I am cautiously optimistic about getting this. I am guessing that few, if any, SOTA people will have 500kHz transmitters so maybe some cross-band tests will be fun. I have yet to build the transmitter but that won’t take too long. I will update you when/if this comes off. Most HF transceivers will receive on 500kHz quite well.

73

Richard
G3CWI


#2

In reply to G3CWI:
Ahh, the good old days of TRs, QTCs, 8 hour watches split into 4, 2 and 2, GLD, GNI, GNF, GKZ, GIL, GCC, GLV, GPK etc…
Good luck with the permit Richard. Had more space on all the ships on which I was R/O for mf aerials than I have here!
I will certainly take a listen for you.
73
Graham G4FUJ


#3

In reply to G3CWI:
What are the power limits Richard? Would be great to work on 500 Kcs with split onto 512.

Graham, you forgot MSG’s SLT’s, Interflora and WX Reports :slight_smile: Not forgetting the bad 2nd Officers who changed ships time each day so you were never sure when to get on watch !!

Regards
David/G4CMQ


#4

In reply to G4CMQ:
LOL
Navwarns, OBS, et al!
Hehe, David, by the time I got to sea, watchkeeping was on local time (though log entries etc. were all in GMT).
Sad it’s all gone now…
73
Graham G4FUJ


#5

In reply to G3CWI:
Richard,

I have a receive converter for 500Khz, and have wanted to try transmitting on VLF for some time but havent found a proper setup. Unfortunately I still don’t have a proper antenna and I think 500Khz across the pond may be pushing our luck…

What level of ERP do you think you will be allowed to run?

In the states it is just about impossible to get an experimental permit for 500Khz, but everyone here, ham or not, can operate on 160-190khz but with a very small signal. One of these days I hope to build or buy an transciver for 160-190…

73,
Tom-N2YTF


#6

In reply to N2YTF:

Tom

I am not sure what ERP I will have as my special licence has not arrived yet (I have been advised that it is in the post). 500kHz should be fun. You can build a transmitter for under $15 - see:

http://groups.google.com/group/uk500khz/web/gw3uep-cw-tx

Across the pond is possible but unlikely with portable equipment. This is especially true as I will be operating during the day. I envisage a maximum range of about 100 miles.

73

Richard
G3CWI
PS I have enough parts to build two TXs so I suspect that Cloud-Gun could be the first 500kHz s2s!


#7

Progress Report

I have built the transmitter (12W o/p). I have an ATU sort of working. I have got a signal as far as Birmingham. A SOTA activation on 500kHz can’t be too long away.

73

Richard
G3CWI


#8

In reply to G3CWI:

Best of luck with this Richard, I remember when the 73 KHz band was first made available & some of the antenna designs were remarkable. I remember a photo of a laundry basket,very similar to one I had in the house at the time, virtually covered in copper wire that was the loading coil for that particular Gentleman’s antenna.

At least 500KHz should be easier, with a wavelength of a round 600 Metres.

It appears that there are already several SOTA stations who have used 500KHz professionally & are familar with it’s particular quirks, & I hope they will help you with any questions you may have.

I do not have a 500KHz NOV or any equipment capable of transmitting more than milliwatts that far down, let alone an aerial! But I can listen out for you if I know you are going to transmit. Would you be able to work cross-band with 80 Metres SSB? My CW is very rusty, but it is getting better.

73,

Mark G0VOF


#9

In reply to G3CWI:
All sounds good - I think I might have to have a bash at this! (In between all the other projects…)
73 Graham G4FUJ


#10

In reply to G4FUJ:

Graham

It is very easy. I built my TX in one evening. I have put a photo here:

73

Richard
G3CWI


#11

In reply to G3CWI:

What you need to do, of course, is qualify a hill with some contacts on 500kHz and some on 10GHz. That would give you the distinction of qualifying a hill with the widest frequency range possible! :wink:

Andy
MM0FMF


#12

In reply to G3CWI:

Hi Richard,

What sort of antenna will you use /P? I would think you
would be lucky to even approach the 1W ERP allowed for fixed
stations, and keep all the antenna within the activation zone!

I have done quite a lot of listening between 200 and 525 kHz,
as I ‘chase’ Non Directional Beacons , and of course winter time
with darkness over the whole path gives optimum DX results.
I usually use a 1 metre square tuned loop indoors, and when the
conditions are right east coast Canada and the USA are no problem
both for NDBs and Navtex. I have also heard most of the regular
UK beacons/ operators, so can recommend this type of antenna for
listeners.

Kind regards

Dave G0ELJ


#13

In reply to G0ELJ:

Dave

My current thinking is to take a 7m pole and fly a wire off the top of it with a kite. Ideally I will aim for 100m total of wire. This will be tuned against a few radial laid on the ground.

I am not certain what sort of daytime range might be possible but people indicate that well over 100km should be achievable with such a set-up during the day. My initial tests have been more successful than I expected but I have yet to sort out the portable aerial.

Apparently there are only about 40 NoV holders - many not actually on - so QSOs could be in short supply. As Andy says, I may need to fall back on a more reliable band such as 10GHz to get the four!

73

Richard
G3CWI


#14

In reply to G4FUJ: For a while there I thought this thread was going to turn into Radio Officers Reunited!

500KHz is a tall order for portable ops from the point of view of antennas, but being mainly groundwave propagation it will be very reliable if you can get it going. Great stuff, Richard, as ever pushing the whole spectrum.

73 Ken GI4FLG (me too - Marconi, Liverpool, 1967 onwards)


#15

In reply to G3CWI:

Hi Richard

I would think you would get out very well if you can get that
kite antenna to stay aloft. Out of interest I have just had a
’daytime’ listen on 500kHz and received G3DXZ from Retford at
about S5 and G3KEV at Scarborough at S7-8. OK, G3KEV has a pretty
substantial antenna system, but so will you!! His distance from me
is about 220km. No preamp used this end just the loop into a Datong
VLF converter into the FT857.

Also have a Drake SPR-4 and a Marconi CR200 TRF LF receiver so will
have to get these dusted off and have a serious listen. Sadly my garden
is much too small for me to get an NOV for 500kHz as the antenna would
have to be too close to adjoining properties.

PS Just heard G3KEV working G3AQC at Chichester

Look forward to hearing you soon

Kind regards

Dave G0ELJ


#16

Dear all

Anyone wanting to have a listen on the 500kHz band will find that almost all modern transceivers go down that far with reasonable performance. All that is needed is a longish aerial like an 80m dipole. The band runs from 501-504kHz. There are various beacons there including GI4DPE (CW on 501kHz) and G4JNT on 503.7kHz, transmitting every 15 minutes at 04/19/34 and 49 minutes past the hour, using the same format as the RAL/ORK/WES 5MHz beacons, but PSK31 for the 30 - 48 second period. There is also a Swedish beacon on exactly 500kHz that I heard last night. http://www.radiorud.se/fyren.asp

There is some CW activity - I have heard several stations. Some use data transmissions or very slow CW.

73

Richard
G3CWI


#17

In reply to G3CWI:

Hi Richard I have been listening around the band and I haven’t heard any beacons on my 80m dipole but I can pick up local motorbikes at 5/9+60dB. Good luck with the project hopefully get a cross-band with you some time. I like Andy’s idea, a cross-band 500kHz/10GHz contact could go down as one of the strangest ones yet.

73 Steve GW7AAV


#18

In reply to GW7AAV:

a cross-band 500kHz/10GHz contact
could go down as one of the strangest ones yet.

…and one of the trickiest. 10GHz is tricky anyway but trying to fly a kite with a 500kHz aerial at the same time would make it a whole lot harder. Interestingly it appears that a lot of microwavers are also on the MF/LF bands which might make things slightly easier.

I have spent that afternoon winding reels of wire for my 500kHz tests.

Quarter-wave vertical and four radials = 750m wire.

73

Richard
G3CWI


#19

In reply to G3CWI:

Would a helium balloon be more reliable than a kite, Richard? Just a thought prompted by a memory that I have somewhere an old Radcom article on balloon borne antennas for 80 metre DXing.

73

Brian G8ADD


#20

In reply to G8ADD:
Actually I heard of someone that uses one of these:

http://www.helikite.co.uk/

…for Top Band work. Apparently he “launches” it after dark (he’s in the suburbs) and cranks it down later.

I’m not sure about one on a breezy summit though!

73 Marc G0AZS