Scanmaster B1300-N vs Scanmaster Airmaster

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Re: Scanmaster B1300-N vs Scanmaster Airmaster

Postby m0lsx » Mon Dec 31, 2018 11:36 pm

waxmax wrote: Would you say Nomads are the best for lofts?


No antenna is ideal within a loft, as the roof will antenuate.
The advantage something like the Nomad has is, versatility.
You hang it from something, or tape it to something.
I have used mine hanging from a window blind. I have used it taped to a fiberglass telescopic pole, my daughter had hers zip tied to the leg of her cabin bed. It will hang in a corner. etc etc.
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Re: Scanmaster B1300-N vs Scanmaster Airmaster

Postby m0lsx » Mon Dec 31, 2018 11:46 pm

waxmax wrote:So back to my original question though: should I get the scanmaster b1300 due to its larger length? As this seems to be case with my telescopic ?


I personally would not. Partly because I do not like commercially built RX only antennas, as they are more often than not, not very good.
Length is about resonance on VHF & UHF & Airband is around 2.5 meters down to 2.2 meters in free space & slightly less than that in the real world. So a half wave antenna would be a little over 1 meters. Thus length is not an issue, unless you can find a colinear airband. Which would be multiple of resonant antennas, over a resonant antenna.
On the longer wavelengths such as on High Frequency, which is around 200 meters down to 10 meters. Then a longer antenna is, or can be better. But not always there either.
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Re: Scanmaster B1300-N vs Scanmaster Airmaster

Postby radiostationx » Tue Jan 01, 2019 1:49 am

The "scanmaster 1300" is a knock off/clone of the diamond d-130/d-300n family which is made from high grade stainless steel, both have been around for ages.
The longer vertical part is a loaded steel whip(there is a loading coil at the bottom) which is for freqs below 60mhz so for you @waxmax that extra height is irrelevant for the civil/mil airband.
One thing is for certain, the discone is no perfect antenna, but its very widebanded and versatile.

The "scanmaster airband" has dimensions that are equiv to a 1/4 wave ground plane antenna for civil airband, the centre driven element having some weather proofing ( a glass fibre tube).

Both are designed to be out in all weathers.

A lot will depend upon your requirements but if its loft mount you are after, something with improved gain is perhaps more desirable.


A slim-jim or j-pole can be constructed very easy and cheaply for a fiver using 2 metres of ladder line such as this.

https://www.radioworld.co.uk/ladder_line/450-s_ohm_twin_feeder_sold_per_metre_

Use the easy calculator below (insert 128 mhz as your freq for civil airband and hit the calculate button)

https://m0ukd.com/calculators/slim-jim-and-j-pole-calculator/

You should end up with something about 1.6m long.

Solder coaxial centre ad braid to the feed points shown in the calc.

Hang it high up in the loft with a drawing pin and place a blob of bluetac at the bottom of the ladder line for ballast to help with maintaining vertical polarisation.

Good to go,If you make it right and cut/solder accurate, I bet you its better or at least as good as both of the above antennas only difference is cost.

A really good airband j-pole is made by Kevin at superyagi antennas..more expensive than a 450 ohm ladder line diy job, but you can make your own first and try out before buying a Rolls Royce of j-poles from him.
Heres a review

https://ukradioscanning.com/viewtopic.php?f=4&t=6478
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Re: Scanmaster B1300-N vs Scanmaster Airmaster

Postby waxmax » Tue Jan 01, 2019 10:09 am

radiostationx wrote:The "scanmaster 1300" is a knock off/clone of the diamond d-130/d-300n family which is made from high grade stainless steel, both have been around for ages.
The longer vertical part is a loaded steel whip(there is a loading coil at the bottom) which is for freqs below 60mhz so for you @waxmax that extra height is irrelevant for the civil/mil airband.
One thing is for certain, the discone is no perfect antenna, but its very widebanded and versatile.

The "scanmaster airband" has dimensions that are equiv to a 1/4 wave ground plane antenna for civil airband, the centre driven element having some weather proofing ( a glass fibre tube).

Both are designed to be out in all weathers.

A lot will depend upon your requirements but if its loft mount you are after, something with improved gain is perhaps more desirable.


A slim-jim or j-pole can be constructed very easy and cheaply for a fiver using 2 metres of ladder line such as this.

https://www.radioworld.co.uk/ladder_line/450-s_ohm_twin_feeder_sold_per_metre_

Use the easy calculator below (insert 128 mhz as your freq for civil airband and hit the calculate button)

https://m0ukd.com/calculators/slim-jim-and-j-pole-calculator/

You should end up with something about 1.6m long.

Solder coaxial centre ad braid to the feed points shown in the calc.

Hang it high up in the loft with a drawing pin and place a blob of bluetac at the bottom of the ladder line for ballast to help with maintaining vertical polarisation.

Good to go,If you make it right and cut/solder accurate, I bet you its better or at least as good as both of the above antennas only difference is cost.

A really good airband j-pole is made by Kevin at superyagi antennas..more expensive than a 450 ohm ladder line diy job, but you can make your own first and try out before buying a Rolls Royce of j-poles from him.
Heres a review

https://ukradioscanning.com/viewtopic.php?f=4&t=6478

So you’d say that the the nomads or a home built slim Jim are the best for lofts due to versatility and gain which can be made specific to airband. How would the scanmaster airmaster compare to these then?
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Re: Scanmaster B1300-N vs Scanmaster Airmaster

Postby radiostationx » Tue Jan 01, 2019 12:54 pm

Hi waxmax,

The difference between the two and given that each would be loft mounted would be very small.
https://www.hamradio.me/nec-shootouts/monopole-vs-jpol-eznec-shootout.html
As said earlier the roof materials will attenuate the intended receive signal and you would have to experiment with different positions.
If you are handy with DIY you can make your own scanmaster airmaster clone and try both.
https://m0ukd.com/calculators/quarter-wave-ground-plane-antenna-calculator/

One thing is certain, decent connection coaxial is a must.
The cheaper coaxial can cause problems in loft mount installs as often the braid can act as a phantom antenna for Broardcast FM stations/unwanted signals from house wiring/electrically noisy motors/other devices.

Both antenna types will not be in free air, they will have purlins, rafters,tiles etc effecting their performance. Sometimes moving the antenna 1 ft or 50p per metre extra on coaxial can make all the difference, we are dealing with tiny fractions of a volt between received weak and dirty s2 signal and a super clean s9+30 signal.

The j-pole/slim jim if made for around 128mhz can work very well on 260-300 mhz mil airband.

Its worth experimenting a bit. Drives you mad at times but thats part of the fun of radio.
When you make your station as good as it can be given the limitations, there is great satisfaction in that.
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Re: Scanmaster B1300-N vs Scanmaster Airmaster

Postby waxmax » Tue Jan 01, 2019 2:04 pm

radiostationx wrote:Hi waxmax,

The difference between the two and given that each would be loft mounted would be very small.
https://www.hamradio.me/nec-shootouts/monopole-vs-jpol-eznec-shootout.html
As said earlier the roof materials will attenuate the intended receive signal and you would have to experiment with different positions.
If you are handy with DIY you can make your own scanmaster airmaster clone and try both.
https://m0ukd.com/calculators/quarter-wave-ground-plane-antenna-calculator/

One thing is certain, decent connection coaxial is a must.
The cheaper coaxial can cause problems in loft mount installs as often the braid can act as a phantom antenna for Broardcast FM stations/unwanted signals from house wiring/electrically noisy motors/other devices.

Both antenna types will not be in free air, they will have purlins, rafters,tiles etc effecting their performance. Sometimes moving the antenna 1 ft or 50p per metre extra on coaxial can make all the difference, we are dealing with tiny fractions of a volt between received weak and dirty s2 signal and a super clean s9+30 signal.

The j-pole/slim jim if made for around 128mhz can work very well on 260-300 mhz mil airband.

Its worth experimenting a bit. Drives you mad at times but thats part of the fun of radio.
When you make your station as good as it can be given the limitations, there is great satisfaction in that.

The airmaster actaully seems rather short compared to the wanted size of 118 airband frequencies from that calculator.
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Re: Scanmaster B1300-N vs Scanmaster Airmaster

Postby radiostationx » Tue Jan 01, 2019 3:14 pm

Yes waxmax it would seem that the airmaster centre freq is around 125mhz and they are using standard 1/4 wave radials not 12% increased size radials.
I prefer 127/8 to work by as 108-117 of the airband isnt much good to us as there are only beacons/nav aids etc there, that leaves 118-137 used for voice transmissions and the centre of that portion is around 127/8.
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Re: Scanmaster B1300-N vs Scanmaster Airmaster

Postby m0lsx » Tue Jan 01, 2019 3:21 pm

waxmax wrote:The airmaster actaully seems rather short compared to the wanted size of 118 airband frequencies from that calculator.


According to the calculator above 118 MHz gives a quarter wave length of 60.9 cm with a velocity factor of 95% & the airmaster is, according to the dealer Nevada, 570mm, (57cm) which is roughly a quarter wavelength at 118 MHz
So the airmaster will be resonant across a chunk of the airband. As what you do is design it with the highest SWR at either end of the desired band coverage.
Ignore the frequencies on the image below. I am just using this only as an example.
What you want is the lowest SWR across the majority of a band. So the highest SWR will be at the band edges.
On a 40 channel radio you would check SWR at 1, 40 & 20.
The curve may see higher swr at 1 than 40 or the other way around, or the same. But you want something like the image below. with a lowering curve across the band.
The length of the antenna is not as important as how the antenna performs & the build material can make a small difference in length.

Image
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Re: Scanmaster B1300-N vs Scanmaster Airmaster

Postby waxmax » Tue Jan 01, 2019 3:34 pm

radiostationx wrote:Yes waxmax it would seem that the airmaster centre freq is around 125mhz and they are using standard 1/4 wave radials not 12% increased size radials.
I prefer 127/8 to work by as 108-117 of the airband isnt much good to us as there are only beacons/nav aids etc there, that leaves 118-137 used for voice transmissions and the centre of that portion is around 127/8.

what about this one : https://www.radioworld.co.uk/radioworld ... 520antenna

has length of 65 cm, so likely to be worse or better than airmaster?
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Re: Scanmaster B1300-N vs Scanmaster Airmaster

Postby radiostationx » Tue Jan 01, 2019 4:34 pm

I am not going to say much on that but it seems like the manufacturer (if this one is one of theirs) isnt exactly renowned for...well I will leave it there..


https://ukradioscanning.com/viewtopic.php?f=4&t=6310&p=34803&hilit=moonraker+rip+off#p34803

(pity the photos are gone now)





If you are thinking of a glass fibre stick co-linear, especially if were to be mounted outside, my advice is to spend a bit more and get a diamond stick or discone for that matter, the quality is great but with a loft space to work in, the d-777 is quite a big stick and may be cumbersome to move around experimenting. Making your own antenna variants with no need for weatherproofing or wind profile worries may pay dividends and save a few bob.
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