International Space Station NA1ISS contact with GB4YOTA

On Tuesday 8th August, there was a planned contact between the ISS and YOTA at 1837 UTC, so I decided to have a listen. There was an issue with the ISS VHF downlink during this pass, so the contact was rescheduled to the next pass, at 2015 UTC. You can hear Paolo IZØJPA apologise for the technical issues they had on the first pass at the beginning of the contact.

I was lucky enough to be able to hear both GB4YOTA and NA1ISS from my location, as the YOTA station was operating from Gilwell Park, which is only 18km NW from my location. The video below shows my reception of the contact. Antenna was a Diamond X-50 on the house, into an Icom IC-7100.

Receiving SSTV images from the ISS – ARISS 20th Anniversary

In commemoration of the 20th Anniversary of ARISS, a Slow Scan Television (SSTV) event took place between the evening of Thursday 20th July until the morning of Monday 24th July. The International Space Station (Russian Segment) was transmitting a sequence of SSTV images showing the history of ARISS on a downlink frequency of 145.800MHz in FM mode and PD120 SSTV mode.

I started receiving them on the Friday, just for fun, but then thought it would be great to collect all 12 images, thinking at the time it might not be possible. However, over the three days, I did actually manage to receive all 12 images. Some I managed to get a few times, giving the choice of multiple images to pick from, others only the one, but I did end up with all of them. 6 of the 12 images I managed to get with no noise, the other 6 are with varying amounts of noise. Read more to see the images. (more…)

1/4 Wave Antenna Calculator

I have been making a few 1/4 wave antennas lately, mainly for UHF and the GHz bands with good success, so I decided to create a calculator to simplify the process and maybe get some people who have not tried one before to give it a go.

For UHF for example, these can be made very cheaply, very easily and they perform well. Try one on 433MHz plugged into your handheld for example 🙂

Go to the 1/4 wave ground plane calculator

The 1/4 wave ground plane

The calculator is at

A long break…

It’s been a year to the day since I last posted an entry here. I have had quite an inactive year with regards to the hobby. Work takes priority of course, but I will get out and about this year and posting a bit more on my blog / pages. I do have some things to update and new pages to add when I have the time such as constructing a 20 element 1.3GHz Yagi, building a 1.3GHz system & some PSU reviews. l also have a few messages and comments to reply to which I am getting through slowly.

It’s been a long winter but spring is finally here so it’s time to get back into the swing of things 🙂

My first 23cm 1297MHz contact!

I recently purchased a 23cm transverter from SG-lab. It’s a 145MHz IF with a L.O. frequency of 1152MHz (default; can be changed). Output power is 2w. Tonight, I had my first QSO on the 23cm band with it with two friends who both have the same transverter, G7UVW and M1GEO. I used a Yaesu VX-6 for the IF, but that went flat, so I switched to the Icom ID-51, which is set to record all QSO’s, so there is an MP3 below!

The transverter comes with a HB9CV antenna etched on a PCB which works really well. I had the ID-51 in one hand and the antenna in the other, holding it out the window. All three of us had the same setup holding the antenna out of or near a window. I first spoke to David G7UVW at 2.2 miles and then George M1GEO at 1.2 miles. Signals were good all round, although it seems the best signal between G7UVW and I was via reflecting off a school building opposite me (or something, the peak signal certainly wasn’t in his direction!).

We are all very happy with the result. I am now going to build a couple of Yagi antennas, look at getting a PA and try out some of the 1.3GHz UK Activity Contests in the summer.

23cm Transverter

My first couple of 23cm QSO’s using a 2w transverter and a handheld.

George M1GEO setup with the HB9CV on a broom stick boom!

The setup of George M1GEO with the HB9CV on a broom stick boom!

Update: The next day, George M1GEO took his transverter up to the 12th floor at UCL in central London. We made contact easily again both with 2w and a HB9CV antenna, over a distance of 14km.

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