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HAM BIG MAC 7/8

B

BOOTY MONSTER

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it isnt made anymore and im sure they would be a small fortune on e-bay , but what is/was the deal on this antenna ? ive read/seen the name droped a few times in threads here and there , but no real conversation on it . im sure some of you guys are familar with it , or even had one ...... so whats th scoop on it ?

THE ONLINE CB MUSEUM: HAM BIG MAC 7/8


HAM%2BBig%2BMac.jpg
 

Hmm that looks like an interesting antenna. I hope you get a reply to your question, can't wait to see whats said. Does anyone know about a super scanner that some guys in the uk bang on about, is it any good or just hype? I've never heard of one myself.
 
delta said:
Hmm that looks like an interesting antenna. I hope you get a reply to your question, can't wait to see whats said. Does anyone know about a super scanner that some guys in the uk bang on about, is it any good or just hype? I've never heard of one myself.
Click to expand...

7/8 wave have high radiation angle. We need low radiation angle over the horizon to get the best results.
Mike
 
sp5it said:
We need low radiation angle over the horizon to get the best results.
Mike
Click to expand...

Not always true.

I don't think this antenna was ever sold stateside, but had quite a folowing overseas.Maybe Jazzsigner or another Euro member can fill us in.



 
With high radiation angle bounce from ionosphere is short. To get long distance QSO lowest radiation angle is the best. Groundwave or bounced.
Mike
 
The Big Mac is the only real CB collinear antenna I've ever seen. This means the antenna is more then just one antenna in a single package. The Big Mac is a 5/8 wave over a 1/4 wave antenna. The coil in the middle of the antenna is a phase correction coil and it provides the proper phase and impedance to drive the top 5/8 wave section.

This is a LOW ANGLE radiation antenna just like the Sigma IV and has very similar performance. The antenna is more complicated then the Sigma IV but don't get your hopes up. Chances of finding one are very slim. Over the years I have talked to a just a few people who have had them. One who had both a Big Mac and a Sigma. His test results indicated the Big Mac was nearly identical to the performance of the Sigma.

From studying these two antennas I have to say I believe the Big Mac may have a slight advantage. This is very small and difficult to measure since we are talking about a few tenths of a db. The person I spoke with who had them both, claimed he felt the Big Mac was stronger however, it was too close to call.

The Big Mac did have a few problems. Snow or ice buildup on the coil insulators will detune the antenna. Bandwidth on the Big Mac collinear is less then the Sigma. It's large size contributes to mechanical failures similar to what we see in the new Sigma clones.

This next part is based somewhat on my theory of how the Sigma works. If anyone disagrees, please feel free to explain. While both antennas are about the same length. Most of us agree the Sigma does not radiate from it's base while the Big Mac does. This would seem to place the Sigma at a disadvantage to the Big Mac.

I disagree based on this. Since nearly no radiation is taking place in the lower 1/4 wave of the Sigma, almost all of the energy is available to radiate off the top section. As the length of a resonant radiator is increased from 1/4, 1/2, 5/8, and 3/4 wave, the RF voltage at the top of the antenna tends to increase. This is why the top 1/2 wave of the Sigma greatly outperforms any other half wave radiator.
 
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The Super Scanner was an Avanti vertical antenna. It had 3 half wave elements that were controlled by a relay switch box located on the antenna. The signal could be switched from omni directional or directional by the relay box. It was a compromise antenna that offered both omni and switchable directivity. Don't expect to provide a highly directional pattern as it can not do this.

It is better then an Imax 2000 but nearly any other beam can outperform it. If you're thinking about hunting a Super Scanner down, do yourself a favor and try and find a PDL II. It is a much more effective beam with dual polarity and still very compact. It will be just as hard to find but can be done on eBay.
 
decent info shockwave, with one correction, was not made by Avanti, Antenna Specialists made them, who ended up eventually buying Avanti, but by that time the SuperScanner had been discontinued. AS was later purchased by Telex/Turner.... Thinking about it, they also bought HyGain, CDE Rotors, and probably many others I cannot think of atm.... I know late production rakers were sold in AS marked boxes... Telex also had a decent inventory of parts for many years..

10 Meter "Super Scanner" Antenna Project - How to Modify the Original Super Scanner for 10 Meters!

Antenna Specialists MS-119 Super Scanner

http://www.hamuniverse.com/kd4wpc6metermod.html


My experience with the antenna was that it was actually quite nice, back when it could be purchased new it was relatively inexpensive, especially when compared with the cost of a regular directional antenna, and a rotor. Plus it was pretty compact, and something that was easily (at least for me) put up solo.

Match that with durable, and instantly steerable it was a pretty cool package. I actually enjoyed running it the most with another larger more traditional directional antenna like the Moonraker 4, it worked very nicely to go from omni-directional, to one of 3 lobes to get a rough direction indication, then Zero in with the Raker...

Loved the setup... I would buy one without hesitation If I could find one reasonable (under 300)... Been considering reproducing my own, wouldn't be that hard...


As for the BigMac, sorry Booty, not much to add on it, have seen it mentioned, and looked at pictures and paperwork on it, thats about the extent of it.
 
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thanks guys . is the first time i saw a pic of it , but ive herd it mentioned befor . thought some might find it interesting . it is a bit different looking
 
A useful co-linear for CB can be made from a 44' center fed vertical. Feed it with balanced line. 10/8 wave. Keep the feed 90 degrees away from the wire for as long as possible.
Build an experimental one from junk wire and TV twinlead. Feed it with yer favorite balanced tuner.
 
As shockwave says the ham big mac was a beast, i only knew of one in my city and it cracked out, was awesome on line of sight and dx so was deffo no cloud warmer. the owner was one of the few people who could compete with my signal around here back then, but i had a significant height advantage being halfway up a hill.

i would think it was better built than modern sigma clones but doubt very much it was as well built as the original avanti sigma. performance wise i'd say the big mac had a slight edge over the sigma and it's clones, but not by much, when you get to this level of vertical antenna the gains between the top performers are probably at best unnoticeable to the average user (except at very extreme line of sight distances) without very sensitive test equipment.

at the time they were around in the uk, legal antenna height was 1.5m loaded whip although radials could be full 1/4 wave, so if you were going to go to the extremes of 27 foot plus antennas you were better off just saying fuck it and installing a beam antenna and increasing gain and directivity with the added bonus of going flat side would reduce/null out much of the local vertically polarised qrm (of which their was no shortage in the 80's with ukcb just having been legalised), especially here in the north of the uk where the weather would rip any antenna not built to a very high standard apart easily.

round about that time i traded my avanti sigma 4 in for a 3 element horizontal beam with an antenna specialists mighty magnum 3 mounted above it, which at the flick of a switch gave you the omni for monitoring/sporadic e/local work out to about 70 miles and the beam for long haul dx. it looked like someones nightmare mounted on the chimney of a very modest uk 4 in a block terraced house,especially when it was all turning, but it worked like fuck.
 

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