So the 2017 holiday expedition was to a holiday cottage near Camelford looking down the valley of the River Camel ( Locator IO70po) Unfortunately I had forgotten to take my ‘lucky’ W3EDP Antenna but had got a spare wire antenna in the case with the Elecraft KX-1 so the holiday antenna comprised a 50ft long wire running from the patio door of the cottage out to a tree about 4m above ground then back to a fence. The wire is just about visible in this photo but the 18ft counterpoise was nicely hidden in the shrubbery.
The station itself was set up in similar vein to previous years with the SG2020 transceiver running through an Elecraft Z11 auto-ATU and then a BNC to 4mm banana jack adapter ( that piece of detail will be explained later).
Every holiday cottage seems to have a small table I can relocate to make things work and this was no exception, the Kantronics KAM-XL TNC being on the left of the picture as a requirement of maintaining my nightly NTS skeds with G4KUJ and DB0NTS.
The power supply bears a little more description. I have a 12V PSU that was more intended to feed a small TV or monitor and since it will give 5 Amperes output it did seem a worthy addition to the go box to power the SG2020. However the noise floor at the QTH was very low… Until the PSU was plugged in 🙁 Then there were quite regular S7 noise spikes together with some roaming noise spikes which would drift through any signal of interest just at the wrong moment.
That made the PSU of choice a 13Ah Sealed Lead Acid Battery which I had to charge up most days from a 13W ‘Solar Suitcase’ I had got from Maplin some time ago.
In general I could get about 2Ah charge into the battery on a good day which gave me a little margin over the 1 to 1.5Ah I would take out in an evening operating session.
So how did it go? Well on battery supply the indicated noise floor was only showing as S1 to S2 so I was hearing countries I would never think of hearing at home like St. Helena, Algeria, Rwanda as well as some weaker Americans.
I was even able to copy some good, clear SSTV signals on 20m using the droidSSTV app on my mobile phone with just audio coupling between the phone and radio.
The scheduled RAYNET HF net on 14th August gave good results on reception at least with the following reception reports for UK stations ;
- G0VPJ – 59
- M0NAS – 59+
- G0KQA – 49QRN
- M0TGC – 27QRN
- M1DFO – 15QRN
On PACTOR though a problem from earlier years with the SG2020 cropped up…. When transmitting the receiver AGC is affected and the gain of the receiver is reduced to almost nothing making establishing or maintaining a connection difficult unless the other station is strong. I had heavily modified the SG2020 years ago and looking at those instructions again it was mentioned that the AGC mod would not help ‘fast’ digital modes :-(. Since I always take a soldering iron on holiday, taking the offending modification capacitor out seemed easy but actually caused me more problems of an unforseen nature :-(.
Now the operation turns to the question of when is a 4mm banana plug, not a 4mm banana plug?
For no particularly good reason I had attached the antenna wires to the banana plug/BNC adapter as shown below.
The problem is that the plug isn’t a perfect tube and when I stripped the set up down to remove the AGC capacitor I pushed the red plug rather firmly into the adaptor.
This meant (though I didn’t realise it at the time) that there was no effective connection between the red plug and the antenna connector and the auto-ATU was now struggling to get any kind of good match, rarely better than 3:1, so the already low powered SG2020 at 10-20W output was going into SWR fold back mode and reducing power to protect the PA. The Atu doesn’t have that kind of protection though and continued to flog itself to find a match, to the point that I could smell something ‘hot’ around the antenna socket of the Atu 🙁
The weather wasn’t particularly good around this time and in a state of denial I assumed the antenna wire itself was broken or shorted to ground through the supporting tree. Putting the KX-1 onto the antenna with its own built in ATU didn’t produce brilliant results either so I persevered though the reports from G4KUJ about my signal strength should have been a clue…
When the weather cleared up a bit and nothing could be found wrong with the antenna I did what I should have done in the first place and put my antenna analyser on it because the results were rather conclusive…
As you can see from the screen, not a hint of resonance anywhere…. What if I wriggle that red plug out a bit though?
… The hint of resonances appear, especially around 7MHz where I wanted. So what if I use the adapter the way the supplier intended?
A more acceptable 2:1 SWR on the 40m band which is good as the Z-11 auto-ATU still doesn’t want to tune the installation and that hot smell isn’t going away :-(. A test with the KX-1 though showed that it was now able to tune the system again.
So, the result of plugging cheap connectors in a non standard way to an adapter is a very unhappy ATU needing repairs and compromised operations on PACTOR for the second week of holiday as I just ran the SG2020 into the antenna without an ATU at all and accepted the reduction in power.
While I tried to take part in the RAYNET HF net on the 21st August, the even lower powered transmissions from me on 80 and 60m weren’t heard by anyone 🙁
The final irony? Removing the AGC modification to the transceiver didn’t have any effect on the receiver misbehaving on data transmissions…
So next time a little more effort in testing and packing appropriate equipment is needed, not just trusting that it will all work out when I get to the holiday QTH.