Icom IC-7100 SO-239 to N-Type

Icom don’t seem to like N-Type connectors. I have an X-50N Co-linear, with about 5 metres of Westflex 103 of which both ends are terminated with an N-Type plug. I used to have the Yaesu FT-897D, which is why I have the N-Type attached for VHF and UHF. Yaesu (at least in Europe) use N-Type chassis sockets for their UHF transceivers, but Icom use the SO-239, unless you buy something like the IC-9100. Since buying the IC-7100, I have been using an adapter.

Today, I decided to change the chassis socket on the Icom to an N-Type. Conveniently, there is no soldering involved. They have used a sprung clip to connect to the socket pin. Perhaps this helps prevent connection problems due to thermal expansion and contraction between the chassis and PCB or any movement in the connector pin itself. You could probably change it without opening the case, but its nice to see what you are doing and to know you are not bending the clip! Below shows the internal socket connections.

Icom IC-7100 RF Connectors

Icom IC-7100 RF Connectors

Icom IC-7100 N-Type fitted for VHF / UHF

Icom IC-7100 N-Type fitted for VHF / UHF

Before changing the socket, SWR was around 1.5:1 at 433MHz with the original SO-239 and PL-259 to N-Type adapter. After changing the socket to a plain N-Type and removing the adapter, SWR is 1.1:1 or better from 430-440MHz (Shown by the transceiver). It shows how critical things like connectors and adapters get at UHF, although most of the miss-match was probably the adapter. It also makes it easy to remember which port is HF and which is VHF/UHF. A mod well done. If only Icom built them with N-Type sockets in the first place! Oh, and whilst I had the lid off, here is a photo of the inside of the IC-7100 🙂

1:1 SWR after changing the chassis SO-239 to an N-Type socket

1:1 SWR after changing the chassis SO-239 to an N-Type socket

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8 Comments

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  1. Where did you buy the N type connector please?

    Thanks

    1. Hi Simon.
      I actually got this one from Yaesu UK! I asked Icom but they said they could not guarantee compatibility, I presume because they don’t sell the 7100 with an N-Type anywhere in the world! I did have to file a flat area on the Yaesu one to get it to fit however.
      Cheers, John.

  2. Did mine as soon as I got it for Christmas ☺ had an old ft 7100 from yaesu I took the N connector from,what with the mic mods it may turn out to be a half reasonable radio all the best 2E0TSA

  3. Hi John ,came across your site. Today you really confirmed as to what i have been stating for some time the benefits of having, [N] type connections at Vhf/Uhf. This i think lets Icom down on lots of their Tranceivers. your explict explaining and the photo,s on how to do this Mod is excellent. have a Icom 7100 which my wife purchased for me a few months ago. when the Warranty exspires i will go ahead and do this simple Mod. many thanks for your Info this matter. Good DX KEN 2E0TVP PLYMOUTH DEVON

  4. Looks as if the center pin of the connector is not soldered. True?

    1. Yes, true. Its not soldered. Just clipped in.

    2. It is not soldered intentionally; the inside of the radio heat up and the PCB expand/contract. In the long dimension, the expansion is quite high, and can crack solder joints. Instead they use a spring clip, which allows movement. In the past, they used to use a small piece of wire 😉

      1. Yes, that was my thinking behind it 😉

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