ScannerDude244
Member
Will a 5 element make a big difference over 3? I'm using mfb1500 with 40ft lmr400 for conventional VHF some sites come in weak i'm wondering if 5 element is worth it over the 3? Here is a sound clip
3 vs 5 element yagi
- Thread starter ScannerDude244
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prcguy
Member
Going from a 3 element to a 5 element can give you between about 1.5 and 2dB more gain and that depends on the design. You should hear a very slight improvement or reduction in noise.
ScannerDude244
Member
I was looking at getting this one not sure on they compare to Laird yagis
PCTEL 150-174MHz 7.1dB 3 Element Yagi Antenna (MYA1503KN)
MAXRAD 150-174 MHz 3 element yagi Field tuneable 7.1dB gain, 300 watt. Learn More!
www.solidsignal.com
prcguy
Member
I thought you had a 3 element now and were looking at a 5?
I was looking at getting this one not sure on they compare to Laird yagis
PCTEL 150-174MHz 7.1dB 3 Element Yagi Antenna (MYA1503KN)
MAXRAD 150-174 MHz 3 element yagi Field tuneable 7.1dB gain, 300 watt. Learn More!
ScannerDude244
Member
No i'm using omni MFB1500 150-156 MHz, 350 Watts,Unity G N-Male Conn, White Fiberglass - Talley Inc.. I want to get a yagi to replace it just wonder if 3 element over the 5 is worth it.
prcguy
Member
My motto in life is, if some is good more is better and too much is just right. I have a couple of Sirio 6 element Yagi's and I love them. Partially because the gain is good for the size but also because they cover a wide frequency range with no tuning. The W140-6N covers 140 to 160MHz continuous and works well. You can usually find these from a US distributor. Sirio WY140-6N VHF 140-160 MHz Base Station 6 Element Yagi Anten [wy1406n] - $146.00 : Sirio Antenna, High Performance Antenna Made in Italy
ScannerDude244
Member
OK I'll check that out
Ubbe
Member
Before you spend that $150, try a low noise amplifier. Almost anyone of them will improve reception in a scanner but the PGA103+ based ones are one of the best. You can get a $25 one and use at the scanner as a test and if you get one that can be powered from the coax you can install it at the antenna and power thru a $15 bias-T. If you then also use a CATV splitter at the receiver it will load the coax with a constant impedance, and the amplifier will do the same at the other end and also load the antenna with a constant impedance.
You'll need to attenuate the signal to where the scanner/receiver works at its optimum. Use a variable 0-20dB attenuator and set the level where you get the lowest noise. Even if you improve the antenna an amplifier will still improve the signal even further.
/Ubbe
ScannerDude244
Member
This is a Motorola cdm1250, but I been looking at the minicircuits amps. Also I do have a trunk VHF site blasting 2 miles from me
Ubbe
Member
Then disregard the suggestion about preamps. My experiance with professional Motorola radios are that there will be no advantage using preamps. Actually these later models incl CDM often have a feature to set city or urban use, changing the sensitivity but raising the high signal capability to not be desensed. If I program a radio with the urban setting and it is used by taxi cabs that sometimes drive in the city, then they will come back and complaint and I'll need to set the radio to city use.
The older families of Motorola gear didn't had that urban/city selection and never had any problems and still had the same sensitivity, or even better, than the newer range of radios. I guess it is cost savings involved.
/Ubbe
n5ims
Member
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Remember that going from your vertical omni to a yagi (3, 5, or even more elements) you're making major changes. First off, you will no longer have 360 degree coverage like your omni has. A yagi is directional so you'll only have good signal in a few degree segment in the direction the yagi is pointed. In general, the more the elements the sharper the area of good signal will be. For example, you might have good to great coverage over a 30 degree area and zero coverage over the rest of the range. There may be some spikes of signal around the circle, but those will be minimal. If you only care about a certain location, a yagi works great but if you want multiple locations you'll need a rotor to turn it around as desired (knowing that you'll still only get one at a time).
Please note that commercially, they make yagi antennas with as many as 13 elements (perhaps more if you hunt) and most will allow you to stack 2 or even 4 of them to add even more gain. Here is an example (kinda extreme) on stacking antennas to increase gain and directivity. Equipment | Amateur Radio – PEØSAT (vgnet.nl)
Please note that commercially, they make yagi antennas with as many as 13 elements (perhaps more if you hunt) and most will allow you to stack 2 or even 4 of them to add even more gain. Here is an example (kinda extreme) on stacking antennas to increase gain and directivity. Equipment | Amateur Radio – PEØSAT (vgnet.nl)
ScannerDude244
Member
I know how a yagi works. I had few of them and have a 700mhz one now
ScannerDude244
Member
Ubbe
Member
Same order, Ref-DR-D1-D2-D3. The reason that it doesn't drop down in length equally from D1-D2-D3 are probably that you normally have to change the distance between all elements to change frequency but you do not do that with this antenna. You only trim lengths of all elements to compensate for the impedance mismatch and phase difference and make a compromise compared to a yagi designed for just one frequency that will be more efficient.
/Ubbe
techman210
Member
Then you should have known how “barely directional” and ineffectual a 3 element yagi is. 😃
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