This coming weekend, we’ll be near Tywyn (at SH597014) in a field large enough to set up my inverted ‘V’ stepped dipole. This is cut for 80 metres. I’ve already found that by joining the sides at the apex (centre) and feeding from one end against a counterpoise on the ground, I can use a tuner to get a 50 ohm match. I’ve no idea whether it would be efficient enough to transmit on, so I’m intending to give it a try on QRS CW mid-evening. I’ll self-spot, and would appreciate a call from anyone who can hear me.
To start with I’ll be using about 15W from an FT857, tuning with a Z-11 Pro auto-tuner.
If it works, I’ve a mind to use it when we are near Swanage, Dorset, in September, from G/SC-012.
Any thoughts, advice, comments would be appreciated.
Whilst that configuration may give you a good match, it will be extremely inefficient. If you could somehow make your 80m dipole into a 40m long vertical ground plane, that would work much better
Of course, that may not be practical, but putting up as much as you can vertically with a capacity hat on top does work, the same idea is used on much longer wavelengths than 160m. Google at LF/MF antennas used by NDB’s (aeronautical navigation beacons) for example.
Or maybe you could look at your 80m dipole purely as 40m of wire, you could improve your configuration by erecting it as an inverted L. This is a popular choice of antenna for 160m for a reason & it will out-perform your original configuration quite significantly. Take as much wire as possible vertically from the feed point then take the rest out horizontally to a convenient support. You will need a good ground but a good counterpoise should suffice.
Not knowing what antenna supports you will have available I would probably go for extending each leg of your 80m dipole to make it into a 160m dipole. A lot depends on how high you can get the feed point off the ground, but this would be another more efficient arrangement using the same amount of wire. The current maximum will be in the centre at the highest point & as it is a balanced antenna you should have less problems with RF at the transceiver, although with CW this shouldn’t be a problem. A good ground or counterpoise is recommended though.
After dark, 15 Watts of CW should be OK, & I have worked stations that were using much less, but be prepared to be disappointed. If you have more power available be prepared to use it, remember that whilst your location may be RF quiet, those trying to work you will probably not be so lucky.
Drop me an email to mark@brownhill.demon.co.uk when you have a better idea of timings & I will endeavor to listen for you.
I think it pays to ignore efficiency and just go ahead and try an antenna, after all if the antenna is only 25% efficient your signal will be only one S-point down on a 100% efficient antenna. I have had a number of successful chases on 160-metres SSB using a 102-foot doublet, a G5RV with the matching ladderline extended to the ATU in the shack. This is not something that would normally be regarded as a reasonable Top Band antenna, particularly as it is only 8 metres high, but it suffices. Obviously your end-fed 80-metres shorted dipole will be somewhat more efficient and on the basis of my experience I would certainly consider it worthwhile to give it a go.
I remember back in the 1960s I helped a G3 friend set up a portable Top-band station on Greenlowther GM/SS-056, a 10-watt valve rig with just a centre-loaded whip antenna about 3 metres high, and we got some CW contacts even though the efficiency couldnt have been better than a few percent, so a nice big lump of wire is bound to do better!
I don`t do CW but I will certainly listen out for you and see if I can identify your signal.
don’t know if you remember my very pessimistic alert in December, when I did my first 160m activation, with the comment “don’t expect a huge signal :-)”.
At that time my setup was similar to your suggestions above. I used a long wire in an inverted L configuration, with the vertical part only 10m high, and four short counterpoise wires.
At least I got 14 contacts in my log with my 5 watts and CW. Sadly, my first contact would have been a SSB QSO with an UK operator (not a SOTA member). He repeated several times my full callsign DM1LE/P and gave me a rapport of 33 to 44 but at the end he denied that it was a valid QSO because he insisted that German callsigns must end with 3 letters
I should give 160m another try in the near future.
@Dave: Good luck and definitely try QRS CW. My impression was, that 160m chasers are extremely cooperative, as it was one of my first CW activations.
In reply to all:
Many thanks to all for your comments and encouragement.
Some further clarifications:
We’ll be in our touring caravan on a CL. Wellies are standard equipment. Brolly? Sunshade?
I’ll be using what I have to hand, and which could be used for an activation, and which I realise will be very in-efficient. The maximum centre height I can attain is about 7 metres, and the ends will be supported by walking poles at about 1 metre above ground.
I’m very much a rookie cw op, so please bear with me. If the experience isn’t too awfull, I might try cw as part of future hf ssb activations.
I expect to be QRX about 2000G on Thursday, and will spot on SOTA, notwithstanding problems alluded to elsewhere.
For anyone who has dabbled in cw but don’t think they’ve quite cracked it - have a go anyway if you can hear me. I have to write it all down and miss some, but I use a straight key and will send QRS or/and Farnsworth if it will help. Don’t forget all cw ops started from nothing.
In reply to G4MD:
Thanks, Paul. I’m intending to activate Tarrenhendre on Friday (Late morning if its not too hot) so Friday evening will be updating my log etc. If Thursday is successfull, I could try Saturday evening, but it depends on what plans my XYL has. I’m not on the net while away from my QTH so I have to depend on Alerts and Spots.
Well I’ll be blowed, I could actually hear Dave @ 339 with QSB QRN & my local noise here in Blackburn, he’s still calling at about 15WPM on 1830KHz so have a listen.
Edit:Now QRT @ 2017z.
Well done Dave.
Don’t forget to delete the test spot if nobody else does it first.
