Category: Technical

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

Baofeng CH-3+ Desktop Charger

UV-3R+ and Charger

I recently bought a Baofeng UV-3R+ 2m/70cm handheld. I always said I would never buy a Baofeng, but I wanted something cheap that I could throw about at work and not worry about. Anyway, we all know that you get what you pay for in life. It comes with a desktop charger, which had a problem. It has a USB cable and a small DC jack which plugs into the base itself. When I first plugged the DC plug in, it felt weird. It did work, but you had to fiddle with the plug to get it to make a connection. What happened is it had pushed the centre pin of the small DC socket backwards, because it must have not been central in the socket.

UV-3R Charger DC pin bent back

UV-3R Charger DC pin bent back

To fix it, I decided to drill a small hole above the socket, just big enough for the cable, cut the DC plug off and solder the wires direct to the PCB.

UV-3R+ Desktop Charger - Fixed!

UV-3R+ Desktop Charger – Fixed!

Fixed, no connection problems now!

Raspberry Pi as a server

I have always been a Linux fan and have owned a Raspberry Pi for some time which I use for all sorts of things. A new model was released in February, the Raspberry Pi 2 model B, so I got one. It’s quite impressive with its quad core 900MHz cpu and 1GB RAM.
Now my old model B+ was redundant, I decided to set it up as a home server to run some services that I was previously using a cheap VPS for. The server is at http://j0hn.uk and is pictured below.

The j0hn.uk Raspberry Pi server

The j0hn.uk Raspberry Pi server

The B+ has a 700 MHz (clocked to 800MHz) ARM1176JZF-S CPU, 512MB RAM and is using an 8GB micro SD for Storage. It is a very capable little machine and is running many server applications. Power is provided from an iPhone charger at present, but I am currently building a UPS for the Pi, but as of today, its been up since first boot, 26 days ago.

The Raspberry Pi is a great tool for all sorts. More info is at raspberrypi.org

Transceiver efficiencies (FT-897D, FTDX1200 and IC-7200)

The FT-897D is a very efficient transceiver for portable use, perhaps because it is designed for use with battery power in mind. As I recently purchased an Icom IC-7200 to replace it for HF use whilst portable, I thought I would do some tests on the efficiency of them both, and also my FTDX1200 for comparison. The IC-7200 is comparable to most other HF desktop transceivers, using up to 20A with a 100W carrier. (more…)

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