Review: Cheap SMA to BNC adaptors


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I just received an order of SMA to BNC adapters from www.rfsupplier.com. They are cheaper than most other resellers with an adaptor price of $1.60 or $1.80 and $3 shipping for multiple adaptors. More info below the fold for those who are stuck with SMA connectors on their radios, including pictures with various radios and antennas.

You probably want BNC connectors on your HT so you can change antennas quickly. You can go from a rubber duck to a car mag mount to a fox hunt antenna to base station antenna to a dummy load, quickly. Most HTs with SMA connectors have room for a BNC adaptor. If you order a matching pair of adaptors, you can convert your radio and your antenna. Note that the idea is to mount the BNC adaptor on your radio permanently, not just when you need to use a BNC antenna.

  • Picture of adaptorA=B+C, pair suitable for uprading an SMA radio and antenna to BNC when radio incorrectly uses female connector (Wouxon KG-UVD1P , Baofeng UV-5R, Baofeng UV-3R+ (inconsistent with other UV-3R models), FC-1 Frequency counter, motorola).
  • Picture of adaptorB: SMA-BNC adapter SMA Jack to BNC Jack chassis straight (AD-B01SJ-S01SJ-44BS00 && ID=763) = $1.60
    Note: This jack has a recess on the SMA side so it can fit over the NUT which holds your sma connector down or similar protrusion. Note: fits snuggly on Wouxon KG-UVD1P. Note that you can get gold versions of B on ebay or at 409shop.
  • Picture of adaptorC: SMA-BNC adapter SMA Plug to BNC Plug straight (AD-B01SP-S01SP-41BS00 && ID=281) = $1.60
  • Picture of adaptorD=E+F, pair suitable for upgrading an SMA radio and matching antenna to BNC when radio sensibly uses male connector (Yaesu VX-7R, Baofeng UV-3R Mk II, Other Yaesu/Vertex, Icom, Kenwood). You don’t see idiots putting a BNC male connector on an HT but apparently some fool at motorola put a male SMA on the radio and then Wouxon copied and baofeng copied Wouxon on some of their newer models. Yet another reason to convert to BNC; radio always has BNC femaie.
  • Picture of adaptorE: SMA-BNC adapter SMA Jack to BNC Plug straight (AD-B01SP-S01SJ-41BS00&& ID=855) = $1.60
    Note that there is no hex or knurled section on the SMA side of the connector so it is prone to spinning while tightening.
  • Picture of adaptorF: SMA-BNC adapter SMA Plug to BNC Jack straight glodplated (AD-B01SJ-S01SP-11BS00 && ID=279) = 1.80.
    Note that you may want a solid (not rubber) washer under this connector so it fits snuggly against the radio for maximum mechanical advantage/disadvantage when the antenna is hit. Tested to fit snuggly on UV-3R without a washer.
  • Picture of adaptorG: 1 x SMA-BNC adapter SMA Jack to BNC Jack straight (AD-B01SJ-S01SJ-44BS01 && ID=762) = $1.60
    This is similar to adaptor B but narrower and without a recess on the SMA side. I got one just in case adaptor B is too short on some radio.
    • Sub-Total: $14.80
      Airmail with Tracking (Airmail with Tracking Number): $3.00
      Total: $17.80

      Package arrived 10 days after ordering. If you only need one or two adaptors, it may be cheaper to order off ebay (lower postage) but if you need more than 2 it is probably cheaper to order from rfsupplier than most sellers on ebay and you have a more consistent seller, a single shipment, and you can probably reorder the same parts next time. There are some exceptions though, especially for the radio side connector; not so much on the antenna side. You can get some for less than $1.60 on ebay, shipped. rfsupplier has many other series of connectors, adaptors, pigtails, cables, etc. They make custom cables, often cheaper than they will sell you the parts to make it or their standard cables.

      Note that I had one BNC to SMA adapter laying around that registered an SWR of >=10:1 on an antenna analyzer a while back yet measured ok with an ohmeter. Maybe the contact pins were too loose to mate with the mating connector.

      rfsupplier sells adaptor kits which you should check out, including an SMA to BNC kit with 4 adaptors similar to those above. However, these adaptors are not low profile like the ones chosen here so I ordered individual ones. But they have SMA-BNC, SMA-N, BNC-N, BNC-UHF, SMA-UHF, and other kits and prices are usually $6.40 to $10 for a set of 4 adaptors.

      Note that rfsupplier.com seems to be an alias of Shenzhen Superbat electronics (http://www.superbatrf.com/). Note that if you google the part numbers given above, you will find some other sellers, such as rfbat on ebay, superbatrf.com, 409shop, but these adaptors are generally more expensive there.

      As far as ordering additional SMA antennas, in a word: don’t. Get BNC ones. A BNC antenna is a cleaner solution than an SMA antenna with a long adaptor.

      RF testing: Formal RF testing with lab instruments was not done but RF was put through connectors.

      I actually carried out a QSO with KK4SHO on 146.760Mhz using the 8 Adaptors shown in A-F plus an additional ebay adaptor that looks just like F. I also swapped adaptor G into the chain in place of one of the others. At 2W RF power from my basement in an RF hole (difficult location) into the 146.760Mhz repeater using the NA-701BNC antenna. It was not full quieting (it was if I removed the 8 extra adaptors) but it was readable. So there was some noticeable insertion loss. A really good sma to bnc adaptor has an insertion loss of 0.05dB. What loss was seen might also be due to not thoroughly tightening the adaptor string, particularly the two E adaptors which are hard to tighten.

      Bear in mind that some of these adaptors have contact surfaces that are neither gold nor silver plated and are probably best not used in inaccessible locations like repeater installations. Particularly the outer connection on some of the BNC connectors (which is the fingers, not the outer locking sleeve). Chrome does not work as well but is what you get on most new connectors (BNC, N, PL-259, etc.).

      One nice thing about SMA connectors is that these are usually gold plated (this doesn’t cost a lot due to the smaller size). And they come inexpensively in a variety of PCB mount configurations with nicely machined connectors and grounded threaded sleeve. And they are small when you need to crowd in connectors or for internal connections. SMA connectors are good for semi-permanent connections. But they aren’t very good for HT connectors at the user level (but a SMA connector on the radio and BNC adaptor is ok). Where you need to do things like swap antennas when you hop in/out of the car.
      And with the adaptor already installed on the radio, it isn’t a separate item to carry and lose.

      One warning with rfsupplier, they do time out your shopping cart; if you are going to delay finishing your order save the shopping cart page as html so you will have the links to add them again later. However, if you create an account there, your shopping cart is permanent and you get an order history.

      Rather than using two adaptors and your original antenna, you can go with a BNC antenna and just use one SMA to BNC adaptor. The $12 antenna (now $8.50 shipped) I was showing at breakfast is a Nagoya NA-701BNC (409shop is believed to have non-counterfeit Nagoya antennas). This antenna gave 17dB more signal than the dummy load (short rubber duck) that shipped with the UV-3R and about comparable to the performance of the factory antenna that shipped with the Yaesu VX-7R in my informal picnic table test (where I frequently use the radios). It is also about 9dB better than the UV-5R antenna in one test. Note that while this antenna is longer than the stock UV-3R antenna, it is thinner and more flexible and less prone to sticking me in the side so it is preferable for convenience as well as performance. I have checked into one of the nets using the 2W UV-3R from inside a metal big box store (K-mart) using this antenna and I use this one from my basement inside an RF hole. Note that most of the antennas I checked were similar on 70cm, it was on 2m that the rubber duckies often fail to perform. One review preferred the NA-701BNC over the NA-771BNC which is twice as long. Another review thought they saw 1-2 bars improvement on receive back from repeater (courtesy beep or delay?). Diamond RH-771s are probably counterfeit with the same antennas being sold as both brands. Be warned that there are many sellers offering counterfeit Diamond and Nagoya antenna; and some of these do not work well.
      The NA-701BNC is included in some of the pictures below. Note that the little rubber tip on the end can come off when caught on chair arm.

      Do make sure your adaptors are all tightened down. Loose adaptors can cause high SWR.

      Here is my Baofeng UV-3R radio, with an ebay SMA to BNC adaptor (equivalent to F), an NA-701BNC antennas, and a long string of 8 SMA/BNC adaptors A-F together. This is the configuration which was used to make the QSO.
      Radio/Adaptor/antenna, see text

      Here is my Yeasu VX-7R with the SMA to BNC adaptor I have been using continuously for about 10 years (mostly with BNC cable). This is not from rfsupplier. Note that it is not a low profile adaptor and therefore poses more risk to the radio, though it has done well. An adaptor like this is better if you need to connect to an SMA that is not adequately spaced (though if you have multiple connectors you may need to use pigtails).
      Radio/Adaptor/antenna, see text

      Note that I actually keyed up the 146.760Mhz repeater from the picnic table in front of my house with each of the radio/antenna adapter combinations shown below.

      Wouxon KG-UVD1P with adaptor F and NA-701BNC antenna. On left, is the Wouxon factory antenna plus adaptor combination A.
      Radio/Adaptor/antenna, see text

      Yeasu VX-7R with factory antenna and adaptor combination D. Note that it would benefit from a washer under the adaptor flange as there is a slight gap.
      Radio/Adaptor/antenna, see text

      Baofeng UV-3R and factory dummy load “antenna” with Adaptor combination D.
      Radio/Adaptor/antenna, see text

      Baofeng UV-3R with pre-existing adaptor equivalent to F and NA-701BNC antenna. This has been my everyday carry combination for the last several weeks.
      Radio/Adaptor/antenna, see text

      409shop equivalent to B is $3.70
      http://www.409shop.com/409shop_product.php?id=102078
      And a similar gold plated version is $4.90 or $5.20:
      http://www.409shop.com/409shop_product.php?id=103201
      http://www.409shop.com/409shop_product.php?id=104000
      409shop equivalent to C is $5.20
      http://www.409shop.com/409shop_product.php?id=102166
      409shop equivalent to E is $4.20
      http://www.409shop.com/409shop_product.php?id=102079
      409shop equivalent to F is $5.20 in gold or silver or $5.00 with plastic ring:
      http://www.409shop.com/409shop_product.php?id=102456
      http://www.409shop.com/409shop_product.php?id=102457
      http://www.409shop.com/409shop_product.php?id=102164
      And $6.60 in an even lower profile version:
      http://www.409shop.com/409shop_product.php?id=104413
      409shop equivalent to G is $4.50
      http://www.409shop.com/409shop_product.php?id=102483

      An adaptor similar to B but gold plated on ebay, $10/10
      http://www.ebay.com/itm/10x-SMA-Female-to-BNC-Female-Straight-RF-Antenna-coax-WLAN-Connector-Adapter-83A-/290960354260?pt=LH_DefaultDomain_0&hash=item43be96abd4
      Note that this is press fit together, not solid.

      But F is $20/10 and most of the others are more expensive which puts them at a higher cost than rfsupplier.
      http://www.ebay.com/itm/10-x-SMA-M-to-BNC-Antenna-Adapter-Connector-for-Yaesu-Vertex-Icom-Kenwood-/321085039327?pt=US_Radio_Comm_Antennas&hash=item4ac228e2df

      Summitsource has some deals on RG-58 cable and adaptors, which I ordered back in april:

      • Cheap economy grade: RG-58. copper plated solid steel center contector, wimpy aluminum 35% braid over aluminum foil. $6.95/100ft loose coil. This is definitely not the good stuff, even as RG-58 goes, but good RG-58 can be hundreds of dollars per 500ft spool. Note that you should have a crimp connector on each end as the braid does not like being separated and flexed. Note that it is cheaper to order 5x100ft lengths than 500ft; either way, you get 500ft bulk coil (no spool or feeder box). Note that shipping will be about $16 for 500ft. RFsupplier charges about $25/50ft RG-58 but it is better quality cable.
      • Cheap RG-58 BNC crimp connector: $0.47 each
      • Cheap PL-259 crimp connector: $0.95 each
      • Cheap BNC to PL-259 adaptors: $1.12 each

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