Yaesu: ft-70dr antenna

goochster410

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Am I doing this wrong?? I just purchased a new ft-70dr and checked the antenna with both my mfj and my ns1201 vna. Both show a resonance freq of around 143 M but on 146.79 have an swr of 2.8 and impeadance of 106 ohm!! on the c70 band the swr is around 5. I have a tyt that had an antenna that was 7:1 so I changed the antenna to a hys tactical that is 1.5 on vhf and 1.7 on c70. Even Yaesu states in their manual that if you use a different antenna it should be 1.5swr. So is this something that is normal or should I return the unit?
 

wcsd45

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Yep, you're doing it right. My experience is that aftermarket antennas are very often superior to the OEM rubber duck antennas. You will likely have a longer antenna with an aftermarket antenna, particularly 2M or multiband. The OEM antenna will certainly work, but there is a decent chance you can do better. The major ham radio suppliers will have a wide repertoire of HT antennas. Be a bit careful to match the connector type, and sometimes there can be mounting issues around the antenna connection base. I've used antenna like Diamond SRH77CA, and Smiley Antennas (https://www.smileyantenna.com/) has a good selection for amateur radio. I like the 5/8 wave Slim Ducks.

If the HT is used in the car, do not hesitate to use external antenna with adapter/pigtails to get all the connections right. I use Comet CA2X4SR and CP-5. Two versions: NMO or SO239; be sure to match antenna to mount.

If you're really mobile inclined, basic 2M/70cm rigs are modestly more expensive than HT and such a rig could be put to use in your shack, lots more power 50ish watts vs 5 watts on an HT....yep, there is a vortex cost/rigs/antennas into which you may find yourself drawn, but you can successfully stay out by sticking with some basics.

(no affiliation with any of these companies)

Good luck and 73,

Chuck Keely KC9QBY
 

ko6jw_2

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It is difficult to measure SWR on an HT antenna with any accuracy. I have rarely gotten good results with any antenna analyzer even mounting the antenna directly on the analyzer. There are so many variables that you cannot get accurate readings (the radio itself, your hand holding the radio etc.). The Diamond SRH77CA is a good after market HT antenna. I also have the shorter Diamond SRH701A. I've tried many antennas. Don't sweat the SWR on an HT.
 

goochster410

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Yep, you're doing it right. My experience is that aftermarket antennas are very often superior to the OEM rubber duck antennas. You will likely have a longer antenna with an aftermarket antenna, particularly 2M or multiband. The OEM antenna will certainly work, but there is a decent chance you can do better. The major ham radio suppliers will have a wide repertoire of HT antennas. Be a bit careful to match the connector type, and sometimes there can be mounting issues around the antenna connection base. I've used antenna like Diamond SRH77CA, and Smiley Antennas (https://www.smileyantenna.com/) has a good selection for amateur radio. I like the 5/8 wave Slim Ducks.

If the HT is used in the car, do not hesitate to use external antenna with adapter/pigtails to get all the connections right. I use Comet CA2X4SR and CP-5. Two versions: NMO or SO239; be sure to match antenna to mount.

If you're really mobile inclined, basic 2M/70cm rigs are modestly more expensive than HT and such a rig could be put to use in your shack, lots more power 50ish watts vs 5 watts on an HT....yep, there is a vortex cost/rigs/antennas into which you may find yourself drawn, but you can successfully stay out by sticking with some basics.

(no affiliation with any of these companies)

Good luck and 73,

Chuck Keely KC9QBY
thanks.. great info
 

K4EET

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<snip> Don't sweat the SWR on an HT.
Huh? That is not a good way to say that. Especially as a blanket statement. I've had bad "rubber duckies" with very high SWR on HTs before. That kind of situation could take out a final PA if it didn't have SWR foldback protection. And any significant SWR above 1.5:1 or so (depending on the manufacturer) could start to reduce the power output without the user even knowing it to protect that final PA. Bottom line? You really want an antenna that is of good quality with good characteristics and a low enough SWR to stay under whatever the foldback threshold is for that particular HT. In reality, it is easier to shoot for an antenna that actually exhibits a low SWR when mounted on the HT in question and using the HT as designed even though it takes some really specialized test equipment to determine what the measured SWR would be.
 

ko6jw_2

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Huh? That is not a good way to say that. Especially as a blanket statement. I've had bad "rubber duckies" with very high SWR on HTs before. That kind of situation could take out a final PA if it didn't have SWR foldback protection. And any significant SWR above 1.5:1 or so (depending on the manufacturer) could start to reduce the power output without the user even knowing it to protect that final PA. Bottom line? You really want an antenna that is of good quality with good characteristics and a low enough SWR to stay under whatever the foldback threshold is for that particular HT. In reality, it is easier to shoot for an antenna that actually exhibits a low SWR when mounted on the HT in question and using the HT as designed even though it takes some really specialized test equipment to determine what the measured SWR would be.
Let's start with the assumption that the OEM antenna supplied with your new HT is a piece of junk. Naturally, companies like Yaesu want to blow out the finals on your radio by including worthless antennas. They have designers that know nothing about radios or making antennas.

All right, that's a little extreme and I always use aftermarket HT antennas (Diamond, Comet, Smiley etc). Nevertheless, you will not be able to accurately measure the SWR of an HT antenna. Most amateurs do not have specialized equipment. I have some specialized equipment and have constructed test stands to make these measurements. They are mostly inconclusive although I have gotten good results sometimes. However, there are too many variables in the real world to make precise measurements.

When I said don't sweat the SWR I meant, "Buy the best antenna you can from a reputable manufacturer." They actually know how to design and manufacture good products. They do not want to destroy your new radio. They have the equipment to measure the SWR of their products.

I suggest real world testing. Get another ham at a reasonable distance and do a simplex test with a few antennas and see what reports you get. That's what it is all about.
 

AK9R

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"Buy the best antenna you can from a reputable manufacturer."
And, watch out for cheap, Chinese antennas sold by eBay or Amazon retailers who have nothing to lose if their product damages your radio.
 

ko6jw_2

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Just for general information - The Diamond SRH320A (2m/220/440) antenna tested the best of any I've tried. Below 1.5:1 on 2 meters and 440. A little higher on 220. Don't need 220? Well, the 2m/440 performance is worth it. Just for fun check out the Diamond SRH770S. At 27.5 inches it is one of the longest 2m/440 HT antennas going. I saw aYouTube field test that was impressive. I find it too long for walking around, but in some situations it could be handy.
 
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