If you are like me, you often wonder what Kenwood had in mind when they put an SMA connector on the TH-D7. Not only the connector, but the terrible antenna that attaches to it.  SMA connectors were never intended to be used in an environment where they are constantly changed, as the duty they get as an HT antenna connector. Real SMA connectors do not turn the center pin as you turn the outer shell, but a rubber duck antenna does, adding abrasion to the center conductor.  Not only is it difficult to connect an external antenna to the 'D7, but any coax larger than RG-174 will put too much strain on the connector for comfort.  People have been noticing that metal chips get embedded  in the SMA insulator.  Not an ideal situation.

The antenna that comes with the 'D7 is also a disappointment.  I didn't check it myself, but I understand that it resonates somewhere around 160 Mhz, pretty far out of the band.  As many other people have testified, it seems to be an ineffective antenna.

Recently, at a hamfest, I found a BNC to SMA adapter that has a very substantial rubber support.  It screws into the SMA antenna and allows you to connect either BNC antennas or BNC cables without worrying about breaking the connector.  I use BNC's whenever I use RG-58U, so it was ideal for my situation.  It can be left on the SMA connector, thus helping to prevent metal chips from forming. These adapters are made by Stephen, KC2BHO.  Info (from him) appears below.   I get no commissions for listing this,  I'm just passing it along.

For a new antenna, I chose a Diamond RH 519.  It looks good, like it belongs with the adapter.  I actually measured the antenna resonance with an MFJ 259B ( directly, not through the adapter ) and found it resonates at about 146.5 Mhz, with an impedance close to 50 ohms resistive, and an SWR around 1.5 to 1.  It seems to outperform the stock antenna, although I haven't performed any precise measurements.  I plan to do some measurements with the antenna and adapter as soon as I get a test fixture made up to adapt an SMA connector to the MFJ 259B.

So there you have it, a decent performing antenna that looks good, and the ability to quickly change to an external cable.  The cost? about $40 for the antenna ( mostly ) and adapter.  Maybe not the cheapest solution, but I'm very happy with it.

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KC2BHO's info follows. Any questions, comments, etc., please contact him.

Adapter features:
Gold contacts for best connection.
A low profile design with a rubber covering for a factory antenna look.
The rubber base seals to the top of the radio with no spacers needed for moisture and dirt protection.
The base provides an excellent support for all your antenna applications.
No need to remove to make any antenna changes.

Sizes-to-fit-radio-models:
Yaesu: VX-5, VX-1, FT-50-R, VX-10, VX-110, VX-150, VXA-100, VXA-120
Icom: IC-R2, IC-T8A, IC-T81A, IC-Q7A
Kenwood: TH-D7, TH-G71, TH-F6A
Alinco: DJ-V5
Standard: C508A, C510A
Radio Shack: HTX-200, HTX-400, HTX-245
Aor: AR-16

The following is a list of part numbers and the different radios
they can be used on:

Part # BGA-76
Yaesu: VX-5, VX-1
Icom: IC-Q7A
Kenwood: TH-D7, TH-G71
Alinco: DJ-V5
Standard: C508A, C510A
Radio Shack: HTX-200, HTX-400
Aor: AR-16

Part # BGA-77
Icom: IC-R2, IC-T8A, IC-T81A
Radio Shack: HTX-245

Part # BGA-78
Yaesu: FT-50-R, VX-10, VXA-100

Part # BGA-79
Yaesu: VX-150, VX-110, VXA-120

Part # BGA-80
Kenwood: TH-F6A

Previewed in the Nov. 2000 Issue of QST magazine and the
May 2000 Issue of CQ Magazine.

$11.95  + $1.50 S+H (One to unlimited)
(Check or money order only)
(Specify-radio-model)

STEPHEN G. GULYAS
706 LALOR ST.
TRENTON, N.J. 08610
U.S.A.

I welcome any questions or comments at my email.
gulyas@earthlink.net
Thanks.  S.G.G.  KC2BHO 73's