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#1
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SSB antenna
I am installing an Icom 802 ssb with a 140 tuner. I am looking for
advice/experience on the difference in performance between Shakespeare's 17'6" whip vs. the 23' whip. I have a sloop with a split backstay and probably will go with a whip.I only have about 3' between the antenna base and the mounting clamp on the transom. Insulating the backstay and running the feed wire along the split (through the bimini) is my second choice. |
#2
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SSB antenna
Roger wrote:
I am installing an Icom 802 ssb with a 140 tuner. I am looking for advice/experience on the difference in performance between Shakespeare's 17'6" whip vs. the 23' whip. I have a sloop with a split backstay and probably will go with a whip.I only have about 3' between the antenna base and the mounting clamp on the transom. Insulating the backstay and running the feed wire along the split (through the bimini) is my second choice. The length of your boat and backstay might help us, here for the number crunchers. Test Receiver (Rx) side first, manually adjusting tuner with power off. Rx adjustments will be similar, reflecting Transmit (Tx) potential. Consider not insulating your backstay. Just disconnect it's ground / bonding at the transom. Insulate it with hose to transmit. Feed point by hanging coax centre only to the midpoint of the split, or insulate one leg of split from the centre or base and feed the other bottom. Leave coax shield unconnected at Antenna feed point. Experiment with directivity and relative sensitivity by monitoring a distant transmitter while you power in a circle, or adjust matching. You might be able to tune some by shortening the coax shield and / or connecting the shield end at the maching box or transmitter by switching R.F. capacitors in series with the shield, or disconnecting the shield from ground and connecting it to Tx ground, chassis or power lead ground. It is generally not good to use DC wiring as part of the Antenna Counterpoise, but sometimes it will work a miracle. Consequential lightning or static damage can occur, frying other stuff. Methods abound. This method of grounding can be like connecting a welder / commercial electroplater to your prop and zincs, etc. unless they are isolated, insulated from ground bonding and R.F. sources. R.F. capacitor bondings can also be cobbled to lifelines, etc, sometimes to good effect. At R.F. distances from the ground connection, ground or power return wires can become energised WRT other elements, acting as counterbalancing antenna elements. Here, the more the better, except for errant pedestrians. Antennae are like cat's wiskers, sensing the wind is easier with differential signal sensitivity, like hearing sonar returns through multi-mike differential time delay systems, steering the sense of hearing. Some bondings are to be avoided. Polarisation can also be fiddled, with goniometer tech and time delay devices. Understanding R.F. and ground / counterpoise / lightning plans is a heated subject, hereabouts. Much fun to watch. Terry K |
#3
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SSB antenna
Roger wrote:
I am installing an Icom 802 ssb with a 140 tuner. I am looking for advice/experience on the difference in performance between Shakespeare's 17'6" whip vs. the 23' whip. I have a sloop with a split backstay and probably will go with a whip.I only have about 3' between the antenna base and the mounting clamp on the transom. Insulating the backstay and running the feed wire along the split (through the bimini) is my second choice. The length of your boat and backstay might help us, here for the number crunchers. Test Receiver (Rx) side first, manually adjusting tuner with power off. Rx adjustments will be similar, reflecting Transmit (Tx) potential. Consider not insulating your backstay. Just disconnect it's ground / bonding at the transom. Insulate it with hose to transmit. Feed point by hanging coax centre only to the midpoint of the split, or insulate one leg of split from the centre or base and feed the other bottom. Leave coax shield unconnected at Antenna feed point. Experiment with directivity and relative sensitivity by monitoring a distant transmitter while you power in a circle, or adjust matching. You might be able to tune some by shortening the coax shield and / or connecting the shield end at the maching box or transmitter by switching R.F. capacitors in series with the shield, or disconnecting the shield from ground and connecting it to Tx ground, chassis or power lead ground. It is generally not good to use DC wiring as part of the Antenna Counterpoise, but sometimes it will work a miracle. Consequential lightning or static damage can occur, frying other stuff. Methods abound. This method of grounding can be like connecting a welder / commercial electroplater to your prop and zincs, etc. unless they are isolated, insulated from ground bonding and R.F. sources. R.F. capacitor bondings can also be cobbled to lifelines, etc, sometimes to good effect. At R.F. distances from the ground connection, ground or power return wires can become energised WRT other elements, acting as counterbalancing antenna elements. Here, the more the better, except for errant pedestrians. Antennae are like cat's wiskers, sensing the wind is easier with differential signal sensitivity, like hearing sonar returns through multi-mike differential time delay systems, steering the sense of hearing. Some bondings are to be avoided. Polarisation can also be fiddled, with goniometer tech and time delay devices. Understanding R.F. and ground / counterpoise / lightning plans is a heated subject, hereabouts. Much fun to watch. Terry K |
#4
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SSB antenna
Roger,
We have the 23' whip and it works great. Also have a split backstay, but since the whip was on the boat when we bought it, I decided to stick with it. I'm not familiar with the 17' whip you mention. It would appear to me that you may not be abot to get good tuning acrosss the bands. The specs for the tuner say that a 23' minimum length is required if I recall correctly. Doug, k3qt s/v Callista "Roger" wrote in message om... I am installing an Icom 802 ssb with a 140 tuner. I am looking for advice/experience on the difference in performance between Shakespeare's 17'6" whip vs. the 23' whip. I have a sloop with a split backstay and probably will go with a whip.I only have about 3' between the antenna base and the mounting clamp on the transom. Insulating the backstay and running the feed wire along the split (through the bimini) is my second choice. |
#5
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SSB antenna
Roger,
We have the 23' whip and it works great. Also have a split backstay, but since the whip was on the boat when we bought it, I decided to stick with it. I'm not familiar with the 17' whip you mention. It would appear to me that you may not be abot to get good tuning acrosss the bands. The specs for the tuner say that a 23' minimum length is required if I recall correctly. Doug, k3qt s/v Callista "Roger" wrote in message om... I am installing an Icom 802 ssb with a 140 tuner. I am looking for advice/experience on the difference in performance between Shakespeare's 17'6" whip vs. the 23' whip. I have a sloop with a split backstay and probably will go with a whip.I only have about 3' between the antenna base and the mounting clamp on the transom. Insulating the backstay and running the feed wire along the split (through the bimini) is my second choice. |
#6
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#7
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#8
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SSB antenna
thanks for a very informative post, i've often wondered about using the
copper plate i use for a lightning ground as an rf ground. but tell me, with the long wire, do you catch any fish? ok, no hook, do the birds leave it alone? cheers bruce On Fri, 23 Apr 2004 05:06:19 +0000, Larry W4CSC wrote in part: Another great improvement when you are cruising is to keep 100' of small cable attached to the ground terminal of the tuner. Throw this cable off the stern with a small drag on its open end to make it lay out in the sea behind the boat. This makes an AMAZING RF ground! Just don't forget to coil the cable back up before entering any port and |
#9
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SSB antenna
thanks for a very informative post, i've often wondered about using the
copper plate i use for a lightning ground as an rf ground. but tell me, with the long wire, do you catch any fish? ok, no hook, do the birds leave it alone? cheers bruce On Fri, 23 Apr 2004 05:06:19 +0000, Larry W4CSC wrote in part: Another great improvement when you are cruising is to keep 100' of small cable attached to the ground terminal of the tuner. Throw this cable off the stern with a small drag on its open end to make it lay out in the sea behind the boat. This makes an AMAZING RF ground! Just don't forget to coil the cable back up before entering any port and |
#10
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SSB antenna
On Fri, 23 Apr 2004 05:06:19 -0000, Larry W4CSC
wrote: In any HF radio installation, the closer the antenna is to resonance (1/4 wavelength long or 1/2 wavelength long) at the desired operating frequency, and the further it is located in the clear from CONDUCTIVE surfaces, the better it operates. Why do you think an antenna operates better if it is resonant? Regards Gary |
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