Is the dipole horizontally polarised by any chance?
No, the dipole was mounted vertically on a fishing pole about 16ft clear of the ground.
The collinear was mounted 15ft above the ground on 3 x 5ft poles.
Failing these possibilities I suspect the simplest explanation of a 6
S point discrepancy must be some sort of magic.
I`ve never claimed to be a magician, I merely noted the readings on the S meter. However, I would refer the gentleman to the explanation I gave Andy, a few minutes earlier.
Failing these possibilities I suspect the simplest explanation of a 6
S point discrepancy must be some sort of magic.
Or the S meter scale on the 857 is horribly compressed. Unfortunately despite running an 857 myself I cant give a view on that as I generally use my ears when giving signal reports. Does that mean that as I get older and my hearing starts to fail, everyone will get worse reports? Will have to look back through the logs to see how Im faring!
Now, as you are well aware, I am a big fan of the simple dipole,
however, the collinear simply blew it out of the water. The improvement on
receive was between two and a staggering six s points.
A 6 S point increase is nominally 36dB.
Indeed it is! *
In the specifications for the Diamond X-300 colinear, they claim 6dBi gain on 2 metres. (That is 6 dB over isotropic). To convert to gain over a dipole, we subtract 2.2 dB. That gives a claimed gain of 3.8 dBd, which is less than one S-point.
If Mick is really getting a 6 S-point improvement over his dipole, there is something seriously wrong with the dipole! If the dipole had been horizontally polarised, I could have believed the claim because you can expect a 27 dB loss due to cross-polarisation. However, Mick insists that his dipole was vertically polarised. Bear in mind, however, that a dipole`s performance will be seriously impaired if the feeder is allowed to hang down adjacent to the lower leg of the dipole. The feeder of a vertical dipole must be mounted in such a way that it leaves the feed-point at right angles to the antenna for at least a half-wavelength before dropping down to ground level.
Personally, I would not spend £150 on a colinear to achieve less than an S-point advantage over a home-made dipole and considerably more weight to carry! YMMV!
Mind you, I have known some S-meters, especially on VHF/UHF equipment, that are calibrated such that one S-point = 3 dB.
Mind you, I have known some S-meters, especially on VHF/UHF
equipment, that are calibrated such that one S-point = 3 dB.
I was under the impression that 6 dB per S point was standard on older American equipment but 3 dB per S point is usual on modern Japanese equipment. I emphatically agree that the evidence suggests that there is a serious problem with the dipole!
I was under the impression my TS570 (bought new in 2003) had a lazy S-meter but on driving it with signal generator showed it was correct and each S point was near enough 6dB not to worry. I think it was a bit optimistic on the difference between S9+20 and S9+60 but I wasn`t really too concerned there.
I must try the 817 meter calibration sometime. I don`t use it as a meter more an indicator of not much signal, some signal and lots of signal. A task for which it is perfectly suited.
Wow - what a thread hijack!
Regardless of the arguments about beam / dipole v colinear, the results speak for themselves (208 contacts). Also if a marginal chaser knows the activator is using an omni directional antenna they may stick around longer in the knowlege the activator isn`t about to beam off them.
ps - tried to spell check this post & received an error message.
Yes, it now bears absolutely no relation to a discussion on how a new activator should operate SOTA on 40/30/20m. A bit like asking how to make a pina colada and getting recommendations on which beer is best.
But I got my Pinacolada, errrr, operating tipps and don´t feel as a victim. Just enjoyed reading (and learning) the friendly discussion here while listening to OK1EQ/p on 40m. Btw my proposal for the guilty one in the 6-units-topic: the so called S-meters… On Hf I now enjoy the otherwise controversial RBN-network of skimmers as a very useful tool for antenna comparisons.
Best regards,
Chris (DL8MBS)
still hoping for the wx-front to move slooooowly
A bit like asking how to
make a pina colada and getting recommendations on which beer is best.
73, Gerald G4OIG
Of the more nationally available brews I find Marstons generally quite good. However, the real gems are to be found in the local brews, if somewhat more of an acquired taste at times. :>)
The feeder of a vertical dipole must be mounted in such a way
that it leaves the feed-point at right angles to the antenna for at
least a half-wavelength before dropping down to ground level.
This has not been the case Walt, the feeder is dangling down ajacent to the dipole leg.
Personally, I would not spend £150 on a colinear to achieve less than
an S-point advantage over a home-made dipole and considerably more
weight to carry! YMMV!
I purchased the Sharman clone of the Diamond X-300 for portable use for less than half the price of the Diamond.
Mind you, I have known some S-meters, especially on VHF/UHF
equipment, that are calibrated such that one S-point = 3 dB.
I`ve noticed that when my SLAB is under a load from the FT-857 the voltage meter on the FT-857 is 1 volt lower than the multimeter voltage reading.
Bear in mind, however, that a dipole`s performance will be seriously
impaired if the feeder is allowed to hang down adjacent to the lower leg of
the dipole. The feeder of a vertical dipole must be mounted in such a way
that it leaves the feed-point at right angles to the antenna for at
least a half-wavelength before dropping down to ground level.
I wonder if the way round this is to use a J-Pole configuration (ie, an end-fed half-wavelength, approx) as the active element for a vertical YAGI.
Well, that would explain why it`s not working properly!
It was probably the world`s first 2m NVIS antenna
So the yin of amazing gain is balanced by the yang of a faulty reference antenna and the disturbance in the laws of physics is corrected. More importantly we will continue to use the 2M18XXX on contests along with the hassle of a another mast/rotator and keeping it in the air instead of investing in ten bobs worth of wire and phasing coils.
"When you can measure what you are speaking about, and express it in numbers, you know something about it. But when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind.
It may be the beginning of knowledge, but you have scarcely in your thoughts advanced to the state of Science,"
I`ve noticed that when my SLAB is under a load from the FT-857
the
voltage meter on the FT-857 is 1 volt lower than the multimeter
voltage reading.
This seems to be the general case with both the 857 and 897, it must
be an artifact of how the voltage is measured.
I`m relieved you noticed this too, Brian.
Very annoying, especially /P.
The voltage reading from the rig deceived me on a number of occasions. This was before I took the trouble to put a meter across the SLAB under a load and got the true condition of the battery. In the meantime, I`d got my supplier to send me a fairly expensive, ultra deep cycle, 20Ah SLAB, before I twigged it was the meter on the rig which was playing games
Yes Mike, you will find the voltage reading on the 857 sags even lower if you tag a BNOS 180W linear onto the end of the rig. Extremely satisfying though watching the bar graph light up on the linear, even though my 12AH slab only provided enough power to get through 8 QSOs!
I still think the way to go is low(ish) power and a huge array. Just think of all that lovely gain on receive.
73, Gerald G4OIG
who does drink Marstons Pedigree - on occasion
and don´t feel as a victim. Just enjoyed reading (and learning) the friendly discussion here while listening to OK1EQ/p on 40m. Btw my proposal for the guilty one in the 6-units-topic: the so called S-meters… On Hf I now enjoy the otherwise controversial RBN-network of skimmers as a very useful tool for antenna comparisons.
