directional gainmasters

[bob85]

what high gain antennas Eddie, you know there is no such a thing as a high gain vertical cb antenna,

just some with a little less loss,

some that are longer to raise current maxima while having a fight with their own lower 1/8wave,

some that are even longer to raise current maxima even higher & don't have a fight with their lower 1/4wave,

some that are hat loaded to raise current maxima even further above ground at the same tip height,

plus a miriad of antennas that don't have the expected pattern or noise levels because they are connected to conductive masts ground wires & unchoked feed-lines.


LC
i get a small increase when i point the side with the hat towards the direction i want to talk, possibly not noticable on anything but a steady carrier like FM.

 

[bob85]

mudfoot,
its FM that does the damage, SSB & AM especially big swinging AM are MUCH easier on amplifiers and antennas.

 

[bob85]

Eddie.
I have said it before, GM mounted in the clear is the best white stick I ever tested at multiple locations as a throw it up antenna,
no messing with radials isolators chokes, or so I thought,

GM has inexcusable mechanical issues ( weakest white stick in wind ) & electrical issues ( 200w FM power rating ) that sirio won't fix,

nobody makes a wind-proof high power 1/2wave ground-plane, preferably with an inbuilt isolator,
a 1/2wave is easier to make wind-proof,

can you imagine how you market a good 1/2wave telling people it will equal or out perform their 5/8wave end-fed if its mounted at the same tip height and why that is, when almost everybody else in the cb antenna game have spent years telling people the 5/8 is the dogs bollocks of antennas & showing inappropriate patterns of ground mounted 1/4-1/2-5/8 waves over a perfectly conducting infinite ground-plane,

what a great idea 5/8's are,
you get to use more tube to make a less robust more floppy antenna that performs no better than a 1/2wave at best when both are correctly installed at the same tip height,

antennas need to be able to withstand 100+MPH winds or they are cheap fall apart garbage imho,

in the last week within a few miles of me we have had

1X sirio 827 lose its radials,
1x sirio tornado snapped at the base insulator,
1x bent twisted & cone broke new vector 4000,
1x bent new vector 4000,
2x snapped IMAX
1x snapped gain-master
multiple banana shaped venom/ silver rod type,

that's just the ones I know about, there's more,

astroplane & i10k are undamaged so far and penetrator 500 survived pulling the 9" rawl bolts holding the 20ft mast loose from the wall, now swapped for imax until winds go away,

navs IMAX snapped a few days back so he made a sirio 827- imaxtron99 1/2wave

827 hub & coil form / IMAX bottom section / a99 middle & top section,

I just gave him another 827 to convert to a 100mph 1/2wave.

I don't believe any mainstream manufacturer is the slightest bit interested in making antennas that last,

take my buddy blind AL as an example,

he had 1x 2 section super big stick & 2x sirio 827 break in a few years & 1 blown base amplifier due to open circuit 827,
been blind he was paying commercial antenna installers to supply & errect his antennas, that dismal situation would have continued every year or two had i not intervened,

for the last 13 or so years he has had the I-10k up on the same mast ( UNTOUCHED since it was erected ) as those fall apart go open circuit & blow your amplifier antennas were sited,

if they made antennas that last nobody would be buying new ones.

 

[nav2010]

This was the Antronmax 827 during construction. 827 hub, Imax lower section and Antron two upper sections. To tune it needed a 10pf coax stub in parallel to the coil. Now up and running, SWR 1.1 to 1 on my local frequencies and only 1.2 to 1 on frequencies 700khz either side of resonance which is quite good. Had good radio reports so far.

 

[nav2010]

Half wave BTW and no radials

 

[bob85]

roll your own from from the busted antennas you have lying around ,

 

[M0GVZ]

I'd be proper worried if turning the antenna so the coax was facing a station resulted in an increase in anything. It suggests that the coax is forming part of the antenna which is something that coax coil built into the bottom of it is supposed to prevent.

 

[M0GVZ]

i have no idea how much of a change 1 s-unit is on an ic7600.

3dB from S0-S9, 6dB above S9.

nobody makes a wind-proof high power 1/2wave ground-plane, preferably with an inbuilt isolator

Because the legal limit for DB is 4W-12W in pretty much the entire world hence the reason Sirio won't do anything about the 200W FM limit either.

There is however a company that does make such an antenna, albeit not half wave but rather .64 wave although it does come with a proper set of radials. Take a look at this beauty,hey'll sell and ship to the USA too however the downside is its £300 for UK and £450 for USA so not cheap.

http://www.vortexantennas.co.uk/shop/quasar-q64-vertical-mk2/

m0ogy has a review of it on his Youtube channel, if you watch that it gives you a real indication of just how over-engineered this is.

 

[bob85]

Connor,
if sirio had not made all the stupid claims and just said

maximum power FM mode 200W *50% duty cycle *
maximum power SSB mode 500W + *NO COMPRESSION*
maximum wind survival < 60mph *NO GUY LINES*

all would be well,

they may handle more on other frequencies but not 27.78125 or frequencies close to that,

yes i have seen the vortex quasar, know who smoked his for the same reason the gainmaster won't handle power,
neither vortex or sirio seem to understand how stub matching & coax ratings with high vswr work,

they realised the stub match setup was never going to handle 5kw with high vswr above the stub so they copied the i-10k trombome match,

it still wont take high power like my i-10k,

i was playing with my buddys vortex Q82 yesterday,
vortex use the strongest thickest heaviest tube ever seen in any cb antenna,
it makes my i-10k look like a whimp,

but its ott, thick walled & heavy, comes in a minimal number of sizes so their antennas have a low number of long sections making them heavy as hell and top heavy to boot,

i much prefere a faster taper high section count of .058" wall tube, its lighter & stiffer when used to build antennas.

 

[Mark Malcomb]

Eddie my old jrc meter is stingy vs a typical cb,

people still talk about gain-masters here but not in the same way they did when they first came out,

the game is up for 5/8 gain-masters pronounced "GAYMASTERS" in this area,
the honeymoon is over.

the last GM that went up was on a popular ch19 gateway & did not last more than a week because of vswr rising with the high duty cycle of gateway use at way below rated power,

they break in wind far too easy & won't handle more than about 200w for long overs on uk FM,

the 1/2wave version is a bit stronger & handles more power in the real world.

You're killing me Bob, I'M officially going to tear down my "Gay Master" and move back to Suffolk county where I spent 4 years in the service. Wow I may have made a poor choice on this Bloody antenna, At least I don,t have to pay the Tax for antenna we used
to. I really appreciate that insight, Brilliant chap.. Thanks Bob,,,,,MM

 

[M0GVZ]

they realised the stub match setup was never going to handle 5kw with high vswr above the stub so they copied the i-10k trombome match,

it still wont take high power like my i-10k,

Just how much power do you think you need? 5kW is only a single S point on a CB meter more than 2.5kW and 2 S points more than 1kW on a CB meter or just 1 S point on a meter calibrated to IARU standards.

Whilst 5kW may sound like it'd make a massive difference over 2 or even 1kW the truth is that it doesn't. Once you get over a 100W or so you're terrain limited more than anything and if you are high enough above sea level not to have the curvature of the earth getting in the way you tend to find you need a whole lot less power anyway and even 10W will get you 50+ miles with relative ease.

 

[bob85]

i don't need 5kw connor, but that's what they claimed it would take,
i run 25w & have zero interest in fighting with the acom 1000 club on ch19.

Mark,
don't take it down if its working ok, they do work great if you don't want high power rating and don't get strong winds,

still don't know what to make of the directivity claims if connor is correct my locals see almost 3db change rotating the antenna,

sounds crazy, i need to check it out with my GM.

 

[Marconi]

Bob I'll wait to hear your own testing results. Have you talked to either of these locals or did some other local tell you this revelation?

I can't model a GM precisely, but I can get a good match with a 258" inch radiator while using a 23pF capacitor at the source feed point near the middle of the antenna. Here the match equals R= 47.66 +J 5.907 ohms = 1.139 SWR. Without the match the antenna shows R=178.3 J +J 305.2 ohms = 14.222 SWR. The maximum gain is 3.59 dbi at 9* degrees TOA. The model is copper wire and is 0.3" inches in diameter. It is sitting on the ground (Earth) and the mast is 0.45" inches in diameter to simulate closer to coax diameter. This mast is not isolated from the bottom of the antenna. I have a 1pF choke at the top of the mast. This was done to minimize currents flowing on the mast. Here I'm assume this is a simulated feedline in this case, and it is intended to show the feed line effects...as if I had a feed line attached to the model.

I do not see any skewing and this model in Free Space shows an Average Gain result = 1.

If these guys GM's show 3 db gain in some particular direction...then I say go for it.

Keep us posted.

 

[bob85]

i talk to them often, its what they are claiming Eddie,
seeing any change at all is surprising to me, weather is not right for playing antennas its who's antenna aint broke or damaged week.

 

[Marconi]

Well I guess you could look at it that way,

So, you haven't actually seen such change in signals from these 2 guys.

If you have to put your GM antenna up in order to maybe figure out this riddle from England...you might ought to be careful, if Momma' don't like it, and she cuts your servings of Apple Pie down to nothing.

IMO, this antenna is not worth it.