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Gizmotchy Beam Antenna...Coming Review
- Thread starter Robb
- Start date
The two antennas I am going to test first will be the IMAX against the Gizmotchy.
Here are some of the guidelines:
Both at 36 high at the feed points.
The Gizmotchty will have Belden 9913Flex coax for the vertical & flat side.
Same for the IMAX - which it has already.
Both antennas are greater than 36 ft away from each other.
I will be in a mobile with a Galaxy radio with a very stingy but accurate meter four miles due East of where the station is. The beam will be pointed in that direction. I will be using a switch between the antennas - including the flat side of the beam. The base station will be a Grant XL with a standard 4 watt output.
Any other controls that should to be used?
Here are some of the guidelines:
Both at 36 high at the feed points.
The Gizmotchty will have Belden 9913Flex coax for the vertical & flat side.
Same for the IMAX - which it has already.
Both antennas are greater than 36 ft away from each other.
I will be in a mobile with a Galaxy radio with a very stingy but accurate meter four miles due East of where the station is. The beam will be pointed in that direction. I will be using a switch between the antennas - including the flat side of the beam. The base station will be a Grant XL with a standard 4 watt output.
Any other controls that should to be used?
B
BOOTY MONSTER
Guest
im new to beams and hope to try to build one this spring/summer . but i cant undertand how they can even make a gain claim for their power booster / extra reflector element without knowing how many elements are on the beam it will be added to .
just using maco as an example....
MACO :: Products>Antennas
their 104c has 3 db gain over the 103c , but as each additional element is added the ammount of gain from each reflector is less and less up to the point where the 108c only has .5 or 1/2 a db of gain over the 107c . im sure these are approximate specs and each installation will have its own unique conditions that affect their measurements . but once you go past 5 or 6 elements , going by their claims the gains are minor IMO . not to mention the cost of the bigger rotor and sturder tower/support structure for the big boys . a 3 or 4 element seems to give the biggest effect for the dollar .
just a few questions and thoughts from someone trying to learn about beams and make some sense of it all .
just using maco as an example....
MACO :: Products>Antennas
their 104c has 3 db gain over the 103c , but as each additional element is added the ammount of gain from each reflector is less and less up to the point where the 108c only has .5 or 1/2 a db of gain over the 107c . im sure these are approximate specs and each installation will have its own unique conditions that affect their measurements . but once you go past 5 or 6 elements , going by their claims the gains are minor IMO . not to mention the cost of the bigger rotor and sturder tower/support structure for the big boys . a 3 or 4 element seems to give the biggest effect for the dollar .
just a few questions and thoughts from someone trying to learn about beams and make some sense of it all .
how are you going to account for the difference due to cross polarization?
also, at that distance, the TOA (take off angle) isn't even a factor. at greater distances, the TOA will greatly affect both antennas performance.
in "real" situations, changing the height-above-ground will alter its TOA.
are you going to measure RECEIVED signal strenght? bear in mind that most man-made electrical interference (aka white noise) is verticaly polarized and the beam "should" be much quieter as far as noise is concerned.
ok, there's some "problem" areas :blink: i thot of. here are some positive ideas.
i recommend that you do not use voice to make the comparisons, it's too subjective,...... use a two tone generator.
only measure the DIFFERENCE in received signal, that will account for the background noise issue. if the noise level is 3 db and the signal is 7 db, then the actual signal is 4 db.
have fun
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Cross polarization doesn't need to be part of this test. Because -of course- the vehicle that is measuring these signal strengths is going to be vertically polarized. But I will include it as part of the account. The Gizmotchy 'flat side' or 'horizontal axis' on this particular antenna isn't exactly horizontal. It is actually shaped more like an inverted "V". But I will measure all of the data and include it in order to be complete.
AS far as using a signal generator when transmitting from these antennas. I will do that. I built a variable audio frequency generator a few years back. This will keep an even transmit signal from the radio being used. Can do.
AS far as using a signal generator when transmitting from these antennas. I will do that. I built a variable audio frequency generator a few years back. This will keep an even transmit signal from the radio being used. Can do.
You know what would be cool, a PDL-2 up against the 2 ele Gizmotchy. I would be curious which would be better.
AP
AP
The antenna from Gizmotchy arrived today via UPS just 10 minutes before this post. It was pretty light - a lot lighter than I had anticipated. Considering it is still in the packing boxes as well! A light weight antenna needs a smaller rotor, and this can save the user extra $$$ in the process of getting one of these rascals up.
The review will be ongoing, so these are the boxes and a quick look at how small this came packaged. I must tell you , that I am pleased it is so light! Including the shipping boxes - the weight is just a little over sixteen pounds.
The review will be ongoing, so these are the boxes and a quick look at how small this came packaged. I must tell you , that I am pleased it is so light! Including the shipping boxes - the weight is just a little over sixteen pounds.
Attachments
The weather forecast for my area says that rain will dominate this area for several days.
Might take a bit longer to put this antenna up.
In the mean time, I will be collecting necessary materiel to complete this project.
Tom Charles pointed out to me on the phone, that all of the Gizmotchy and Maco products have tamper-proof seals on them. This is to assure that what you get in the box is complete when one is shipped out to you.
Seal on box means all of the parts inside have been carefully accounted for
Might take a bit longer to put this antenna up.
In the mean time, I will be collecting necessary materiel to complete this project.
Tom Charles pointed out to me on the phone, that all of the Gizmotchy and Maco products have tamper-proof seals on them. This is to assure that what you get in the box is complete when one is shipped out to you.
Seal on box means all of the parts inside have been carefully accounted for
Attachments
I couldnt believe how light that antenna was when it arrived aswell I was thinking what the hells missing out of the box LMAO!! When it was all put together I think its like 12-13 pounds!!! I have a Ham 4 rotar under mine and believe me the rotar doesnt even know the antennas there its such an overkill. You could easily use a TV antenna rotar to turn this antenna without a worry.
I am going to ad the booster kit this spring I was just amazed in the perormance of this antenna for a 3 element assembly is a breeze you have all the mesurement right on the diagram which helps Im thinking about getting another one to tune at another portion of the band for the kids to use on there bench.
How heavy is just the booster kit?? extra 2-3 pounds Im guessing??
I am going to ad the booster kit this spring I was just amazed in the perormance of this antenna for a 3 element assembly is a breeze you have all the mesurement right on the diagram which helps Im thinking about getting another one to tune at another portion of the band for the kids to use on there bench.
How heavy is just the booster kit?? extra 2-3 pounds Im guessing??
The specs say that the "Power Booster" is four pounds.
I think it might be closer to three pounds.
I took the instructions out of the box and read them carefully, so I would have a leg-up when it came to put it together. As Tom Charles pointed out to me, all of the aluminum radials are exactly the same lengths for each section. That agrees with what I see here. As an ex-machinist, I appreciate this kind of workmanship. The liberal use of stainless steel hose clamps for the radials also makes for the use of quality parts in this kit.
I think it might be closer to three pounds.
I took the instructions out of the box and read them carefully, so I would have a leg-up when it came to put it together. As Tom Charles pointed out to me, all of the aluminum radials are exactly the same lengths for each section. That agrees with what I see here. As an ex-machinist, I appreciate this kind of workmanship. The liberal use of stainless steel hose clamps for the radials also makes for the use of quality parts in this kit.
That's an easy one. The PDL II was the best 2 element beam ever made for 11 meters. No other 2 element beam will beat it. That is a fact. It's driven element is a full wave quad fed by a half wave. The design was years ahead of it's time. The PDL is about equal to a 3 element Yagi.
I used to have one of them old PDL-2 With that copper rejection wire kit and plastic hubs this was another antenna they stopped production like so many others. The only antenna I think that should have been continued and would have sold like hotcakes nowdays is still the Superscanner rotar free electronically switched beam I have 4 of these put away with some extra parts that eventually Im just going to sell because like alot of the other beams I have and had put away Ill never use them Im more than pleased with what Im using as a matter of fact I also have a 5 or 6 element Jogunn thats still in the box if anyone is in or near Wisconsin I may just sell this thing aswell.
The wall thickness of the horizontal support beam is .065 of an inch. The radials have a wall thickness of .050 of an inch. I will ask him what aluminum alloy was used the next time I talk to him. Which should be be pretty soon. I will post those results - as well as other facts in the actual review.