In the Shack

Testing Coax for Faults

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It’s been a while since I was regularly operating my station and much of the coax that is in use has been exposed to the outside environment for over 10 years. I know the best way of testing coax is by using specialised sweep tools, but having only basic testing equipment available I though I should ask the Ham Radio community over on Google+. I think Google+ is an entirely underrated social platform, and I find myself leaning towards it’s use more and more.

Some of the advice coming back I expected, such as investing in an MFJ-269 or FoxDelta Analyser (which is good advice by the way, I see an antenna analyser being next on my purchasing list). However, I think Tim (VK2XAX) provided me with some excellent advice to get started:

Yes there is a couple of things you can do with basic ham shack items:

  1. stick your power/SWR meter on a small patch cable with a dummy load directly on the output of a 2m radio. Set you power out to precisely 10 watts aka 40dBm call this p1. Remove meter from rig. attach suspect cable to rig. attach meter and dummy load to end of cable and measure power again without touching rig output power. call this p2.
    p1-p2 = loss for your cable.
    look up spec sheet for your cable e.g. RG213 has a loss of ~15db@100MHz for 100m so 15/100 = ~0.15dB loss per metre. e.g If your cable is 34m in length then it should have a loss of ~5.1db aka about 3.5w.
    If your 34m cable shows a different value to 3.5w then you should be able to calculate that loss and work out how much worse than the specs it is.
  2. If you have a big dummy load, stick that on the end of the cable with the SWR meter at the radio and pump up the power to max and see if there is any SWR – there should be none. If there is SWR then the cable is most likely damaged in some way that is causing reflection These are good “rule of thumb” tests to check your cables.

Tim then went on to detail in a separate Google+ post a demonstration of his testing.

I was quick to check out the second of the two items, as high SWR was my immediate concern (The SWR without ATU seemed a little higher than I remembered, ranging between 2-3:1). I was pleased to find that it is not the coax contributing to the SWR (which means I need to look at the balun next…). The loss measurement will also come later.

Other more obvious inspections I have done are:

  1. Continuity – just use a multimedia so find any obvious issues like open circuit, or short circuit  between the conductor and ground.
  2. Visual – Inspect Coax and connectors for any physical signs for deterioration such as oxidisation around the connectors and ground braid and  any indications that the outer jacket of the coax has been damaged or has become brittle, allowing water to enter the coax.

I have unfinished business with the Coax and dipole, so I am sure there will be a post in the future providing a continuation of the testing.

 

 

Rig Control with RUMlogNG

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My workspace for my radio gear is pretty limited, therefore space is at a premium. The Toshiba Tecra M2 which I used as my station computer for many years finally reached the end of its life, with none of the major operating systems supporting non-PAE chipsets. Not ready to purchase a laptop just for radio operations, I was hoping that I could use a more contemporary platform for operations – an iPad.

A quick search around and I came across RUMlogNG, which is easily the best logging interface I have seen in a ham radio iPad app that is modestly priced.

RUMlogNG Logging Page

One of the more interesting features was that basic interaction with your radio was possible (reading of frequency, mode), with the suggestion to use one of Pignology’s Piglets. Reading the specifications of the piglet, it became apparent that what it was doing was taking the serial CAT interface of the rig control, and making it accessible over wifi network to connected devices by streaming the serial data out of a TCP port.

Armed with this information, went looking for alternative ways to connect serial interfaces to RUMlog, and happened across this forum post, talking about an app called remserial. After attaching a Serial to USB Converter to a Raspberry Pi, I was able to run the below command as root:

pi@raspberrypi ~/remserial-1.4 $ ./remserial  -p 7373 -s "9600 raw" /dev/ttyUSB0

The app did not crash when I tried this, so I assumed it was running, and then configured RUMlogNG to connect to the Raspberry Pi on port 7373. Success! RUMlog did not throw any errors and back on the logging screen, I saw that frequency and mode was being updated off the radio.

Rig Control with RUMlog

Day 1

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Today is the first day of getting back on air. It’s been a pretty full on day actually as I never anticipated the amount of things I needed to do to get everything working. I guess before I continue, I should mention one of these arrived in the mail for me yesterday:

My new Rig
No complaints about this arrival

The Yaesu FT-DX1200 is quite an upgrade from the trusty Icom 706-MkIIG, which has now been relegated to VHF/UHF Duties.

The joy of a playing with a new rig on Friday night was short lived – the new Yaesu draws 23.8A @ 13.8V peak. My power supply was a fair way short of this at 15A. operating would have to wait until Saturday. In the meantime, I could start getting a PC ready for rig control.

Let me just say, you will reach an inevitable point in time when hardware, although suitable for the purpose will not be supported by modern operating systems. I found out that upgrading from Windows 7 to Windows 10 was not supported at 64bit, but was if I would find Windows 10 32bit. The problem here however is that the 32bit download tool will not work under 64bit Windows 7. joy.

I also managed to go out to Jaycar in the morning and buy a 40A switch-mode power supply. Some people will cringe, because these type of power supplies are notorious for causing RF interference (QRM). Fortunately I see very little QRM affecting the rigs.

Ham Radio Battle Station
The Battle Station. Win10 Installing

After installing Win10, I found that the drivers associated with the rig control interface cause the computer to crash. Dammit. back to Windows 7 I have gone. I think I have done about 5 OS install attempts in the last 24 hours.

Finally, I am getting around to configuring Ham Radio Deluxe to control the Rig. I am finding the lack of documentation in configuring the DX1200 quite frustrating and as I am writing this I am looking for information on how to sent PTT to the rig, which will probably take me into the evening.

After this, import my previous QSLs, set up VKCL for the RD Contest in a couple of weeks and start doing a more thorough configuration of HRD.