Fringe VHF Marine Reception Help Needed

[prcguy]

Looks mostly ok to me with the preamp right at the antenna with any filtering before the preamp. The preamp gain is a bit high and I think 10dB attenuation after it would be a good start. The limiter would be used in front of the preamp if you had a VHF/UHF antenna in very close proximity to the Yagi and were running high power. Its meant to protect the preamp at the expense of some insertion loss that will add to the system noise figure. I don't think you need the limiter.

I have a couple of new ZX60-P103LN amps I don't need and could have discounted.

Can I please get some feedback on the configuration I plan to try. Right now I use the yagi and coax. I plan to try:

• Yagi (home brew)
• FM (HPN-30118)
• Preamp (ZX60-P103LN), ~24 dB gain
• 100’ RG6 (Likely 2.5-3dB loss)
• Attenuator (HP with 0-20 dB atten)
• Limiter (HP 5086-7284; 10W max in; 10 dBm max thru)
• Receiver

Everything but the amp has been ordered. I plan to use this for marine band reception tests. After that I will try the components with my airband setup that uses a separate scanner and a discone.

 

[cpfinlay]

Can I please get some feedback on the configuration I plan to try. Right now I use the yagi and coax. I plan to try:

• Yagi (home brew) <- Vertically polarized?
• FM (HPN-30118)
• Preamp (ZX60-P103LN), ~24 dB gain <- I have had outstanding results with mini-circuit pre-amps located at the antennas
• 100’ RG6 (Likely 2.5-3dB loss)
• Attenuator (HP with 0-20 dB atten)
• Limiter (HP 5086-7284; 10W max in; 10 dBm max thru)
• Receiver

Everything but the amp has been ordered. I plan to use this for marine band reception tests. After that I will try the components with my airband setup that uses a separate scanner and a discone.

Sounds like a fun challenge! I made a couple of minor notations above. Looking forward to hearing your results.

 

[iMONITOR]

Sirio WY155-3N VHF 155-175 MHz 7dBi 3 Element Yagi Antenna ($130 on Ebay)




Features:

• Base station antenna, Directional
• Wide band, High-gain
• Highly symmetrical radiation pattern in both planes (E and H)
• Protection from static discharges DC-ground
• Made of anodized aluminium alloy
• Stacked and bayed array for more gain
• Optional: tilting bracket for +-20°
  Electrical Data
  
  
• Type: 3 elements yagi antenna
• Frequency range @SWR ≤ 1.5: 155-175 MHz
• Impedance: 50Ω
• Radiation (H-plane): beamwidth @ -3 dB = 140°
• Radiation (E-plane): beamwidth @ -3 dB = 70°
• Front to back ratio: ≥ 16 dB
• Polarization: linear vertical or horizontal
• Gain: 4.85 dBd - 7 dBi
• Max. Power (CW) @ 30°C: 200 Watts
• Grounding protection: All metal parts are DC-grounded, the inner conductor shows a DC short
• Connector: N-female with rubber protection cap
  Mechanical Data
  
  
• Materials: Anodized 6063-T5 Aluminium, EPDM rubber, thermoplastic UV stabilized, Chromed brass
• Wind load / resistance: 114 N @ 150 Km/h / 160 Km/h
• Wind surface: 0.071 m²
• Dimensions (L x W approx.): Dimensions (L x W approx.): 990 x 1110 mm
• Weight (approx.): 1740 gr
• Tourning radius: 970 mm
• Operating temperature: -40° C to +60° C
• Mounting mast: Ø 35-52 mm

 

[prcguy]

Too small. I have two of the Sirio 6 element broad band Yagis and they are really nice. 140 to 160MHz with 8.35dBd gain (10.5dBi) or they have a 155 to 175Mhz model. One of the US distributors is Eagle Antenna on Ebay.

WY 140-6N WY 155-6N

6 elements Yagi, Directional, 140-175 MHz @ SWR ≤1.5 No tuning required, Wide Band, Highly Symmetrical Radiation Pattern, Systems: 2m-HAM, VHF Marine Band, O...

www.sirioantenne.it

Sirio WY155-3N VHF 155-175 MHz 7dBi 3 Element Yagi Antenna ($130 on Ebay)

View attachment 88574


Features:

• Base station antenna, Directional
• Wide band, High-gain
• Highly symmetrical radiation pattern in both planes (E and H)
• Protection from static discharges DC-ground
• Made of anodized aluminium alloy
• Stacked and bayed array for more gain
• Optional: tilting bracket for +-20°
  Electrical Data
  
  
• Type: 3 elements yagi antenna
• Frequency range @SWR ≤ 1.5: 155-175 MHz
• Impedance: 50Ω
• Radiation (H-plane): beamwidth @ -3 dB = 140°
• Radiation (E-plane): beamwidth @ -3 dB = 70°
• Front to back ratio: ≥ 16 dB
• Polarization: linear vertical or horizontal
• Gain: 4.85 dBd - 7 dBi
• Max. Power (CW) @ 30°C: 200 Watts
• Grounding protection: All metal parts are DC-grounded, the inner conductor shows a DC short
• Connector: N-female with rubber protection cap
  Mechanical Data
  
  
• Materials: Anodized 6063-T5 Aluminium, EPDM rubber, thermoplastic UV stabilized, Chromed brass
• Wind load / resistance: 114 N @ 150 Km/h / 160 Km/h
• Wind surface: 0.071 m²
• Dimensions (L x W approx.): Dimensions (L x W approx.): 990 x 1110 mm
• Weight (approx.): 1740 gr
• Tourning radius: 970 mm
• Operating temperature: -40° C to +60° C
• Mounting mast: Ø 35-52 mm

 

[MDScanFan]

The high gain of the 105 was one of my concerns vs something like the 103. The atten in the chain should allow me to dial things in.

The limiter is something I planned to buy anyway to place at the hf and vhf/uhf inputs to my receiver. Just in case for the receiver. I don’t think I would have a problem with or without it. I will likely leave in that location for the marine reception trials.

Looks mostly ok to me with the preamp right at the antenna with any filtering before the preamp. The preamp gain is a bit high and I think 10dB attenuation after it would be a good start. The limiter would be used in front of the preamp if you had a VHF/UHF antenna in very close proximity to the Yagi and were running high power. Its meant to protect the preamp at the expense of some insertion loss that will add to the system noise figure. I don't think you need the limiter.

 

[MDScanFan]

The antenna is vertically orientated. Thanks for checking

Sounds like a fun challenge! I made a couple of minor notations above. Looking forward to hearing your results.

 

[MDScanFan]

You guys are tempting me with the Sirio yagis’s. I will resist for now and stick with my home brew. As mentioned earlier in this thread it is designed to give me 9 dBi of gain but I have no way to verify. The match, f/b ratio test, and performance vs my discone indicate it is working as well. I designed two add on director elements that should give me a couple more gains. I plan to add these when I trek back up to the attic with the amplifier, etc.

Too small. I have two of the Sirio 6 element broad band Yagis and they are really nice. 140 to 160MHz with 8.35dBd gain (10.5dBi) or they have a 155 to 175Mhz model. One of the US distributors is Eagle Antenna on Ebay.

WY 140-6N WY 155-6N

6 elements Yagi, Directional, 140-175 MHz @ SWR ≤1.5 No tuning required, Wide Band, Highly Symmetrical Radiation Pattern, Systems: 2m-HAM, VHF Marine Band, O...

www.sirioantenne.it

 

[prcguy]

The preamp will saturate and limit the level into the receiver at a safe level, no need for the limiter.

The high gain of the 105 was one of my concerns vs something like the 103. The atten in the chain should allow me to dial things in.

The limiter is something I planned to buy anyway to place at the hf and vhf/uhf inputs to my receiver. Just in case for the receiver. I don’t think I would have a problem with or without it. I will likely leave in that location for the marine reception trials.

 

[prcguy]

Aah, but you will never know for sure how the home brew Yagi is working. Is it picking up what you need or is it missing stuff because its not tweaked just right? You will toss and turn at night thinking about this, you will loose sleep and will be a wreak. It only costs $149 to fix that problem with a new shiny Sirio WY140-6N! And your home brew would never have the extreme BW that the Sirio has to cover 2m amateur through marine band and still meet specs.

Buy one now, do it. Frank at Eagle Antenna is waiting for your order right now, he is sitting by the phone and will put all other calls on hold for you.

You guys are tempting me with the Sirio yagis’s. I will resist for now and stick with my home brew. As mentioned earlier in this thread it is designed to give me 9 dBi of gain but I have no way to verify. The match, f/b ratio test, and performance vs my discone indicate it is working as well. I designed two add on director elements that should give me a couple more gains. I plan to add these when I trek back up to the attic with the amplifier, etc.

 

[MDScanFan]

Regarding the marine test configuration, I agree, thanks. Separate from the marine setup I am currently running antenna - coax - receiver (hf & vhf ports). No preamp in the chain so I am adding a limiter.

The preamp will saturate and limit the level into the receiver at a safe level, no need for the limiter.

 

[MDScanFan]

I really appreciate the support

Aah, but you will never know for sure how the home brew Yagi is working. Is it picking up what you need or is it missing stuff because its not tweaked just right? You will toss and turn at night thinking about this, you will loose sleep and will be a wreak. It only costs $149 to fix that problem with a new shiny Sirio WY140-6N! And your home brew would never have the extreme BW that the Sirio has to cover 2m amateur through marine band and still meet specs.

Buy one now, do it. Frank at Eagle Antenna is waiting for your order right now, he is sitting by the phone and will put all other calls on hold for you.

 

[dlwtrunked]

Bringing the radio up the the attic is a great suggestion. I will try that when I get a chance. As you point out, it should help answer the coax question.

I just checked and my coax is Commscope F677TSVV. The data sheet shows 2 dB / 100’ at 85 MHz and 2.9 dB at 187 MHz. So probably 2.7 dB loss for my run at 156 MHz. For reference, and equivalent LMR 400 run is around 1.8 dB, which is about 20% less loss. Not a huge difference.
...

Agree--Even a 3 dB loss is in the noise (pun intended) compared to the other factor of height of the antenna. A loss of 3 dB or "half the signal" is not really usually enough to make a difference compared to other factors.

 

[prcguy]

A 3dB loss can be different depending on the receiver and how its internal limiter works. In some radios where the limiter is not so good and takes a wide range to finally limit, a 3dB RF change may get lost in the already present speaker noise at low RF levels. A radio that limits well quickly above its minimum sensitivity rating will provide better quieting and the 3dB difference will be very noticeable within the knee of limiting action.

Also, going to a preamp at the antenna not only makes up for feedline loss before the receiver, it sets the system noise figure at a much lower level. The system noise figure for an antenna feeding direct into a receiver will be mostly affected by the receiver noise figure, maybe 5 to 10dB, plus the feedline loss. Place a low noise preamp right at the antenna and now the system noise figure is just a tiny bit worse than the preamp noise figure (around .5dB for the ZX60-P103LN @ 157MHz) and that can improve system noise figure by 5 or 10dB in some cases.

Agree--Even a 3 dB loss is in the noise (pun intended) compared to the other factor of height of the antenna. A loss of 3 dB or "half the signal" is not really usually enough to make a difference compared to other factors.

 

[wcsd45]

Hello,
Understand coax change is not-preferred option. That aside, give LMR-400 a chance, homebrew or commercial yagi. FWIW, a simple Uniden BC125AT (New or Ebay) or BC780XLT (Ebay) would be decent. Yep, there is a cost but coax/scanner sure is working well here.

Good Luck,

Chuck KC9QBY

 

[MDScanFan]

I plan to try the filter/preamp route before I investigate new coax. Also, if I use a preamp then the quality of the coax is no longer an issue.

Regarding the scanner, I have several scanners and a old 2m mobile. Thus far the 2m mobile performs the best and has not exhibited any intermodal issues. Based on these results, and feedback from others, I think a dedicated vhf radio may be my best bet.

Hello,
Understand coax change is not-preferred option. That aside, give LMR-400 a chance, homebrew or commercial yagi. FWIW, a simple Uniden BC125AT (New or Ebay) or BC780XLT (Ebay) would be decent. Yep, there is a cost but coax/scanner sure is working well here.

Good Luck,

Chuck KC9QBY

 

[WB9YBM]

If you decide on the pre-amp, try to get it as close as possible to the antenna, before weak signals get attenuated further by coax losses.

 

[dlwtrunked]

A 3dB loss can be different depending on the receiver and how its internal limiter works. In some radios where the limiter is not so good and takes a wide range to finally limit, a 3dB RF change may get lost in the already present speaker noise at low RF levels. A radio that limits well quickly above its minimum sensitivity rating will provide better quieting and the 3dB difference will be very noticeable within the knee of limiting action.

Also, going to a preamp at the antenna not only makes up for feedline loss before the receiver, it sets the system noise figure at a much lower level. The system noise figure for an antenna feeding direct into a receiver will be mostly affected by the receiver noise figure, maybe 5 to 10dB, plus the feedline loss. Place a low noise preamp right at the antenna and now the system noise figure is just a tiny bit worse than the preamp noise figure (around .5dB for the ZX60-P103LN @ 157MHz) and that can improve system noise figure by 5 or 10dB in some cases.

Agree--Friis formula (Friis formulas for noise - Wikipedia ). The complicating factor is that the pre-amp must have sufficient gain for this to be realized and then we get into having to add filters that are location/frequency specific and regularly investigated again (which I do).

 

[MDScanFan]

Since my initial posts I have not had a chance to play with my marine antenna setup much. But I did buy an Icom marine radio that shows marked improvement over the scanner I was trying to use. Intermod issues are reduced significantly and the audibility of the signals is generally better. I purchased a 162 MHz Par notch filter that cleans up the intermod further.

You guys put a bug in my ear with a Sirio Yagi. I was looking at the 4 and 6 element versions recently. The 4 element yagi is 5.25 x 3.56 ft and 4.5 pounds. The 6 element yagi is 6.59 x 3.56 ft and 5.5 pounds. My question is do you think a standard j mount would be sufficient to hold one of these? I am considering trying two locations: 1 my attic and 2 mounted to the trunk of a tree. There would be some wind loading for the tree mount but I would not expect it to be significant because it would be fairly protected and mounted only 1/3 up the tree.

 

[prcguy]

A 2" J mount from a DirecTV Slimline dish should work ok for the 6 element if the base is bolted into something solid. The Slimline has optional outrigger arms that make it into a tripod and if you get those it will hold a much larger antenna even on a crappy roof.

Since my initial posts I have not had a chance to play with my marine antenna setup much. But I did buy an Icom marine radio that shows marked improvement over the scanner I was trying to use. Intermod issues are reduced significantly and the audibility of the signals is generally better. I purchased a 162 MHz Par notch filter that cleans up the intermod further.

You guys put a bug in my ear with a Sirio Yagi. I was looking at the 4 and 6 element versions recently. The 4 element yagi is 5.25 x 3.56 ft and 4.5 pounds. The 6 element yagi is 6.59 x 3.56 ft and 5.5 pounds. My question is do you think a standard j mount would be sufficient to hold one of these? I am considering trying two locations: 1 my attic and 2 mounted to the trunk of a tree. There would be some wind loading for the tree mount but I would not expect it to be significant because it would be fairly protected and mounted only 1/3 up the tree.

 

[MDScanFan]

Thanks for your reply. I agree that it seems like it should be ok.