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Stick or Twist?


#1

We’ve all built antennas and ended with bits of wire all over the floor before starting all over again.

About 3 years ago I picked up, just under a Kilometre of wire at a rally, ideal for building antennas.

So far, about 300 metres has ended up in the trash, cut in lenghts varying from a few centimetres to a few millimetres.

I’ve just knocked up a new 2m dipole which is showing a SWR of 1.2.1.

Would you stick or twist :wink:

73 MIke
2E0YYY


#2

In reply to 2E0YYY:

I’m sure you can do better than that. You’re not really trying!

Andy
MM0FMF


#3

In reply to MM0FMF:

In reply to 2E0YYY:

I’m sure you can do better than that. You’re not really trying!

Hmmmmmmmm :wink:

73 Mike
2E0YYY


#4

In reply to 2E0YYY:
“I’ve just knocked up a new 2m dipole which is showing a SWR of 1.2.1.”

I would settle for that at the band edges:)

73,
Colin
M0XSD.


#5

Twist. Experimenting is the only way to develop your own perfect system. 73 Richard G3CWI


#6

1.17.1

Stick or Twist?

73 Mike
2E0YYY


#7

In reply to 2E0YYY:

If you can get to 1.14 : 1 you will have improved the return loss by 3dB from 1.2 : 1

At present you’ve only made a 1.3dB improvement.

Andy
MM0FMF


#8

In reply to MM0FMF:

I’ve been down this route before, Andy. I’m currently using a microscope and scalpel :wink:

73 Mike
2E0YYY


#9

In reply to 2E0YYY:

Use a small file, you can take a few thou at a time off then.

Andy
MM0FMF


#10

In reply to MM0FMF:

Rotfl. Maybe you need to clarify what you mean by a 1.3db improvement. But then again that might spoil Mike’s fun.

73 Richard G3CWI


#11

In reply to G3CWI:
All this fine adjustment is a total waste of time Mick.

Your bound to stand on the damn thing anyway the first time you take it up on those dark, satanic hills!


#12

In reply to G1STQ:

In reply to G3CWI:
All this fine adjustment is a total waste of time Mick.

Your bound to stand on the damn thing anyway the first time you take
it up on those dark, satanic hills!

That’s why I’m building this one :wink:
73 Mickey
2E0YYY


#13

In reply to 2E0YYY:

Perhaps a nice rhombic Mike,

Kind regards

Dave


#14

In reply to 2E0YYY:
LOL!

I must admit to thinking along the lines of 1.5:1 is ok for a portable aeriel - and a bit better is nice but not worth loosing temper over.

There are so many variables with location that really does it make much difference? Just look at your odd-lenght HF set-up and you’ll see what I mean!


#15

In reply to G1STQ:

Super-low SWR is massively overrated. Most radios operate just fine with a higher SWR and even at 3:1 no-one will be able to tell the difference on their S meter.

Without wanting to wake Andy up or cajole him into chasing me with a gun - I still like to refer to this book for a bit of common sense :

http://books.google.co.uk/books?id=wUzQN8GN_zYC&pg=PA20&lpg=PA20&dq=lou+franklin+swr&source=bl&ots=VP-MZ4y6nr&sig=EJhQ6uiybOPMIzjlEfKZ_DGQlpQ&hl=en&sa=X&ei=FnQbUf_uA9C4hAesh4D4Ag&ved=0CC8Q6AEwAA

Cue the debate! ;)))

Rob


#16

In reply to G7LAS:

Of course it is Rob. Lower is better but only within reason. The only reason to really care is if you have a TX that cuts back the power at the slightest sniff of any reflected power. Then you need to ensure the degree of mismatch is low enough not to cause any throttling back in all likely use scenarios. My HF vertical is a bit of ground sensitive pig and can cause the 817 to sulk without a few minutes faffing with the counterpoise.

There are ultra rugged PAs available that will not degrade irrespective of the load applied. But the FT817 isnt one of them!

I’d be interested in what Mickey was using to measure SWR than can resolve a 0.03 change in SWR at 1.2:1. Unless he’s using the kind of precision N or APC connectors they fit to big VNAs (the kind of connector that when I was a student we were told cost more than we got for 3year’s grant!) then the variation in insertion loss on remaking a connection is probably going to be greater!

Anything better than 2:1 is fine in my book.

Andy
MM0FMF


#17

In reply to MM0FMF:

I’d be interested in what Mickey was using to measure SWR than can
resolve a 0.03 change in SWR at 1.2:1. Unless he’s using the kind of
precision N or APC connectors they fit to big VNAs (the kind of
connector that when I was a student we were told cost more than we got
for 3year’s grant!) then the variation in insertion loss on remaking a
connection is probably going to be greater!

Anything better than 2:1 is fine in my book.

Just having a bit of fun, Andy :wink:

Using nothing more sophisticated, than a combination of 3 Watson power/SWR meters. Naturally, they`re all giving a different readings

The worst reading is under 1.2.1, so I’ll settle for that and hopefully test it out on Moel Famau this coming Saturday (if it stops snowing) :frowning:

Just as an aside, I’ve found Moel Famau an excellent summit for both HF and VHF take-off. Have you had much experience of this one?

73 Mike
2E0YYY


#18

In reply to 2E0YYY:

Just having a bit of fun, Andy :wink:

I know hence suggesting you try to make it better.

Does Moel Famau have a reasonably steep drop in the direction of the areas of major population density?

Does Moel Famau overlook a large reasonably flat area of the country with a very high population density?

Is VHF SOTA operation something commonly experienced by people living in these areas?

If the answer to all 3 is yes then it will be a good VHF location for SOTA!

Andy
MM0FMF


#19

In reply to MM0FMF:
No, no and probably no to answer the above.

BUT - what it does have is a nice, easy walk where Micky can drag his co-linear up without too much trouble.

We are all waiting to watch him try NW-051 Foel Fenlli (from the carpark - naturally!)

:wink:


#20

In reply to G1STQ:

In reply to MM0FMF:
No, no and probably no to answer the above.

BUT - what it does have is a nice, easy walk where Micky can drag his
co-linear up without too much trouble.

I’ve activated this summit three times (once with you, IIRC) and everyone says what a nice easy walk this is, however, with over 20kgs in tow, not quite so easy.

We are all waiting to watch him try NW-051 Foel Fenlli (from the
carpark - naturally!)

If YOU can manage NW-051 Foel Fenlli, from the car park, then a man with a wooden leg and grand piano strapped to his back should have little trouble :wink:

Ten points is somewhat tempting though, so I may just pair them.

73 Mike
2E0YYY