Posted: 4/24/2012 10:34:54 AM EDT
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I need a SMA to TNC adapter for my VX-8R. My intention is to connect the PRC-152 tape antenna to the Yaesu, even if I have to create a new mounting system so it can support the extra weight.
Or maybe one with several inches of coax between both ends. Where is a good place to find them? Thanks. |
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Or maybe one with several inches of coax between both ends. This. Connecting a 1 meter blade with a solid adapter would be a very easy way to snap off your SMA connector. Also keep in mind that those antennas are designed to cover 30-90Mhz, they *might* be usable up to 115Mhz before the VSWR gets above 3:1. |
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The antenna is spec'd between 30-512 MHz and is 45" long. I do way more receiving than transmitting. If it will transmit on any or all bands, that is a plus for me. What is the actual part # of the antenna? the PRC-148 & PRC-152 antennas that I've worked with only covered from 30-90. |
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http://rf.harris.com/media/prc-152_vrc-110_handbook_tcm26-11408.pdf
12011-2730-01 on page 6 |
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That's an interesting find from a versitility stand point. I will caution you that an antenna that is that wide banded by it's nature will provide equally so/so service across the entire range vs a more narrow banded with some degree gain unless you need the VHF low spectrum. |
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Do you genuinely think you will get reasonable performance out of that antenna over that entire frequency range? It's not possible. Not going to happen. Anyone could take a random length of wire and say "this antenna receives 0.1 to 1000MHz!". Doesn't mean it is actually going to work with any reasonable performance.
If you give us what you want your antenna to receive with reasonable performance, we can suggest a suitable antenna or combination. +1 on the short coax jumper as an adapter, too easy to overstress the connectors otherwise. But, lets get you something that actually works for what you need it to do. |
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Do you genuinely think you will get reasonable performance out of that antenna over that entire frequency range? It's not possible. Not going to happen. Anyone could take a random length of wire and say "this antenna receives 0.1 to 1000MHz!". Doesn't mean it is actually going to work with any reasonable performance. If you give us what you want your antenna to receive with reasonable performance, we can suggest a suitable antenna or combination. +1 on the short coax jumper as an adapter, too easy to overstress the connectors otherwise. But, lets get you something that actually works for what you need it to do. This. I can't remember who it is on here but they do a lot of antenna research and when i was looking at a .mil folded dipole for HF i thought it was great because its 3-30MHz with out a tuner then i learned it just uses a resistor to even the swr out. Short story is if it sounds to good... There is probably a reason a 152 will only go a couple klicks out of the 110 mount. |
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Do you genuinely think you will get reasonable performance out of that antenna over that entire frequency range? It's not possible. Not going to happen. Anyone could take a random length of wire and say "this antenna receives 0.1 to 1000MHz!". Doesn't mean it is actually going to work with any reasonable performance. If you give us what you want your antenna to receive with reasonable performance, we can suggest a suitable antenna or combination. +1 on the short coax jumper as an adapter, too easy to overstress the connectors otherwise. But, lets get you something that actually works for what you need it to do. What kind of performance should I expect with the antenna in question? Is there an easy way (plug numbers into a website) for me to calculate the efficiency based on the antenna length and chosen frequency or will I have to do a manual calculation? I still need a source for the adapter or coax extension. |
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There is probably a reason a 152 will only go a couple klicks out of the 110 mount.
Several clicks with 50 watts? That is horrible. Most of the 30-512 vehicle antennas that I have seen spec sheets on have at best 1.5 dbi of gain at best in a small range and are as bad as -3 dbi in other portions of the range. little or complete lack of gain is the price you pay for a very wide banded antenna. As for your original request here's a link but this is NOT A RECOMMENDED APPROACH |
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I still need a source for the adapter or coax extension.
The VX-8R has an SMA female connector, correct? Universal Radio sells a TNC Female to SMA Male adapter. This outfit will build you a custom RF cable. |
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What kind of performance should I expect with the antenna in question? Is there an easy way (plug numbers into a website) for me to calculate the efficiency based on the antenna length and chosen frequency or will I have to do a manual calculation? I still need a source for the adapter or coax extension. If you're using the antenna somewhere near where it's 1/4 wave resonant, it will work fine. 3/4 wave, kinda ok but the antenna pattern would be screwy. Other than that, its performance is going to suck.... as far as I can tell, those are just a whip and not any kind of inherently broadbanded antenna design. AFAIK you can make your own "blade antenna" with some spring steel pallet strapping and heat shrink. If you made your own you could even make it resonant at a frequency that would work for you. Mil radios are for the most part spec'd to work into very high SWRs so that they will continue to work even with wrong or damaged antennas. That doesn't mean that you will actually get any efficiency out of that kind of antenna, just look at the typical ranges that are often quoted. Mil antennas are designed to be soldier proof not high performance for the most part. |
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There is probably a reason a 152 will only go a couple klicks out of the 110 mount.
Several clicks with 50 watts? That is horrible. Most of the 30-512 vehicle antennas that I have seen spec sheets on have at best 1.5 dbi of gain at best in a small range and are as bad as -3 dbi in other portions of the range. little or complete lack of gain is the price you pay for a very wide banded antenna. As for your original request here's a link but this is NOT A RECOMMENDED APPROACH I figure the longer antenna it is compared to the stock, the better it should be. |
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I still need a source for the adapter or coax extension.
The VX-8R has an SMA female connector, correct? Universal Radio sells a TNC Female to SMA Male adapter. This outfit will build you a custom RF cable. Yes, it has a female SMA connector. Thanks for the links. |
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What kind of performance should I expect with the antenna in question? Is there an easy way (plug numbers into a website) for me to calculate the efficiency based on the antenna length and chosen frequency or will I have to do a manual calculation? I still need a source for the adapter or coax extension. If you're using the antenna somewhere near where it's 1/4 wave resonant, it will work fine. 3/4 wave, kinda ok but the antenna pattern would be screwy. Other than that, its performance is going to suck.... as far as I can tell, those are just a whip and not any kind of inherently broadbanded antenna design. AFAIK you can make your own "blade antenna" with some spring steel pallet strapping and heat shrink. If you made your own you could even make it resonant at a frequency that would work for you. Mil radios are for the most part spec'd to work into very high SWRs so that they will continue to work even with wrong or damaged antennas. That doesn't mean that you will actually get any efficiency out of that kind of antenna, just look at the typical ranges that are often quoted. Mil antennas are designed to be soldier proof not high performance for the most part. I have access to an SWR meter, so I will be doing some testing once I get the proper cabling. |
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There is probably a reason a 152 will only go a couple klicks out of the 110 mount.
Several clicks with 50 watts? That is horrible. Most of the 30-512 vehicle antennas that I have seen spec sheets on have at best 1.5 dbi of gain at best in a small range and are as bad as -3 dbi in other portions of the range. little or complete lack of gain is the price you pay for a very wide banded antenna. As for your original request here's a link but this is NOT A RECOMMENDED APPROACH I figure the longer antenna it is compared to the stock, the better it should be. Incorrect assumption. A longer monopole does have higher potential gain, IF it's properly matched to the radio its feeding, and such matching would be limited in the frequency range it could cover. A half wave monopole would be an ideal HT antenna for performance, if correctly matched at the frequency of use... but a half wave antenna directly connected to a radio would be almost a dummy load on receive and nearly nonexistant on TX as well as having a very high VSWR. More damning is that when you go over 5/8 wavelength at the frequency in use, the radiation pattern starts pointing toward the end of the antenna instead of being broadside to it. You can then put a phasing section in to create a colinear element, but such phasing would be limited in bandwidth and not very feasible with an antenna of that kind of physical construction. The advertised length of that antenna IIRC was 40 inches. .62 wavelength for a 40 inch monopole is a little over 180MHz. IF they put in a matching system to match that length as a half wave, it would be right about at the 2m amateur band which would be about right for the VHF high band military users typically in the 136-150 range. It would then load as a 1/4 wave at probably somewhere in the 60-70MHz range - again, not a bad place to be for military use in many parts of the world. That's assuming that is how they have the antenna set up. But it's going to be seriously compromised for anything in the UHF range due to the length of the radiator, regardless of the VSWR. I have no doubt that they're trying a variety of tricks in combination to try to squeeze more acceptable performance out of that antenna, the simple fact is it's going to be severely compromised in performance over many parts of its advertised frequency range. There are antennas that can give you genuine broadband frequency coverage over a range like 50-500, but it's not going to fit on a handheld. If you want something that can cover a few specific frequency bands, then its a lot more reasonable... that's likely what that mil antenna is actually doing. The only way to know for sure is to get one of those mil type antennas and put it on an analyzer. |
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There is probably a reason a 152 will only go a couple klicks out of the 110 mount.
Several clicks with 50 watts? That is horrible. Most of the 30-512 vehicle antennas that I have seen spec sheets on have at best 1.5 dbi of gain at best in a small range and are as bad as -3 dbi in other portions of the range. little or complete lack of gain is the price you pay for a very wide banded antenna. As for your original request here's a link but this is NOT A RECOMMENDED APPROACH I figure the longer antenna it is compared to the stock, the better it should be. snip snip Gamma hit it on the head. Also remember a dummy load will have great swr as well. |