SG-237 Tuner Control pt1

As I want a relatively discrete antenna arrangement for my radio ham interest, I have opted for a single random length wire with automatic tuning being dealt with by a SG-237 tuner, Part 2 of this blog will go into the fixing details of the antenna and hardware.

I have made a tuner control unit out of a single gang blank faceplate, although this is not required for the basic installation, it will give me some control and confirmation indications at the shack end of power and that the tuner has finished tuning.

The schematic I followed with the exception of the polarity protection diode and Antenna Available ON led, is within the manual available from SG Tuners, I used an small offcut of veroboard to make the unit and this will be inside a backbox, the faceplate displays the lights and access the controls.

board v2

The connections and schematic for my unit are shown here.
schematic from manual

The veroboard layout is shown here.

SG Tuner Board - V2

This is the unit fully assembled but not yet labeled, holes were drilled will a hss bit on a slow speed, letting the drillbit do the work with little pressure, I bought off ebay a Dremel copy, and used the grinding bit to gently open the holes to the right size and also to grind down the faceplate support ridges:

Virgin Faceplate


Labeled unit ready for installation, the label is made in Word or Visio to the right dimensions, printed to plain paper and cut slightly oversize, the reverse of the paper then has double sided self-adhesive tape applied, the front of the label then has a clear self adhesive covering applied (the sort of clear covering you would use for school books), I used a sharp knife, steel rule and cutting mat to cut just inside of the second outer boarder of the label, I printed a double border in case I made a hash of cutting it the first time, at least I could have another shot.

Once the label was ready, I striped down the faceplate, lined it up and carefully stuck it to the faceplate, to cut the holes, I held the faceplate to the light and used the knife to starburst the holes before going round the edges to clean up.

faceplate v2

I have added an led which will light when the longwire is NOT to ground, the transfer will be done by a mechanical knife switch, the switch is a double pole double throw, one contact pole will switch the antenna wire from the SG-237 to ground, whilst the other pole will switch the Anntena Available led, credit goes to Bill O’Neil, KW8KW for a simple but effective solution to what could be a costly problem.


I opted to fit a double dry lining box and to have once side blanked as a spare for future use, the positioning of the tuner control was important as I did not want the display obscured by the PC monitor.

I started by clearing the area:


Offered the backbox to the wall and leveled it with the existing antenna faceplate:

Wall Marked

Bin bag opened and taped to the dado trunking ready to contain the majority of the mess:

Bag in place

Using a sharp utility knife I scored the plaster board along the pencil markings, repeating this a number of times until the blade cuts through (the finishing lining plasterboard is quite thin for my internal walls, so it was quite easy), you can use the alternate method of drilling a hole at each corner and cut the hole with a plasterboard saw or similar.

board knife cut

I knew by tapping on the plasterboard that the fixing adhesive was right in the middle of the hole, to break the cut board out, I split the board worth a chisel and took each piece out, I try not to let the pieces fall into the cavity between the wall and the board, the adhesive was removed using a bolster chisel, notches in the breeze block were needed to allow the fixing wings of the dry lining box to be fully pushed back to clear the plasterboard:

wall exposed

The control cable to the SG-237 tuner was put in place when I was drawing the antenna cables:

cable fished

Drylining box in place with cable conductors pin crimped:

box in ends made off

Cable connected to veroboard:

connected to veroboard

Veroboard sized to fit within rear of backbox:

vero in backbox

Faceplates screwed on and area cleaned up:

faceplate on

Job done, 12v wall wart PSU plugged in all ready for Part2 hardware and long wire installation.

back together

Click for part2

Weather Site Minor Additions

Minor tweaking carried out today:

Added Lightning Analysis tab, this opens another page to show statistics from the Boltek lightning detector.

Expanded to Pollen page to show information from The Weather Channel, I have retained the Chatteris map as this has greater detail on it when you follow the link by clicking the map directly.

Glossary of terms added.

Link from the lightning StormVue NGX and Alerts Page has been set up via the TSentry icon, this link takes you to the Contact Me page – TSentry is the software which send the e-mails when certain conditions are met, have a look at the Alerts Page to see what they are.

Lightning Detectors Working Overtime

Had a good electrical storm that Chatteris Weathers own lightning detectors tracked successfully, the software gives each storm cell a reference number, direction bearing in degrees, distance from Chatteris in miles and it’s status, i.e. weak and steady.

The software will also send subscribers an e-mail when a storm meets certain triggers, a e-mail is also automatically sent when no lightning has been detected for over 30 minutes.

Click on link for further details on the alert scheme – To Alerts Page.

My Humble Radio Setup

I have hopefully finished battering the credit card (well for now), and have the radio and ancillaries, the next purchase will be the external aerial, but I will do another page on that.

I decided on a Kenwood TS-2000 multi-band transceiver as this will give me all the flexibility I believe I require, this is powered by a EP-925 PSU with an output current of 25A and a peak of 30A. All the reviews on this power supply were right in that it is really noisy when the cooling fan kicks in, I have done the mod which is all over the internet and is simply a 1.5K resistor in series with the thermostat, this ‘fools’ the cooling fan circuit and has the fan running at a very low speed all the time, should the thermostat open due to high temperature, the fan will go to full speed and full cooling.


I also bought a Signalink mainly in preparation for PSK31 when I get the aerial sorted, I will also explore all other data modes when I get the chance, the Signalink is configure to Radio Ham Deluxe program and works really well, again I copied others in downloading Skype so I can remote into the TS-2000 from a laptop, currently my license allows me to do this only from within the house as it is still classed as being attended, a full license holder can use this in remote mode away from the house.

I imported a MFJ-949E Antenna Matching Unit, this is not connected to anything yet, but looks nice 🙂


Passed Intermediate Test

Undertook the Intermediate License radio amateur Test under the watchful eye of Cambridge University Radio Club who kindly allowed me to take the test with them, even though I’m not a member, or for that matter ever got past going to a comprehensive school!

The test comprises of 45 multiple choice questions on all aspects of the syllabus, once the test is over, the invigilators provisionally mark the paper straight away so you know if you have passed or not.

I got two questions wrong, and although you do have to wait for official confirmation, I’ve passed….Yeah.

Front Page Season Countdown Error Fixed

Noticed that the Season Countdown timer on the main index page had missed out the Summer and went straight into the countdown to Winter from Autumn, I thought this was a bit harsh as we have to give Summer a go at least, the fault turned out to be where I had changed the Americanism of ‘Fall’ to Autumn, this had upset the script, so made really minor word changes and it seems to be ok again.

Weather PC Backup

The Acronis True Image 2013 backup software in online ‘real time’ mode has caused me some problems since the 28th May when I enabled it, with the Weather Display application hanging  and therefore generating a Clientraw data received error on the web site. I have reverted back to incremental backups every 24 hours, bit of a shame that the backup software won’t work as advertised (plenty of user comments on this when googled), but at least this method works.

Weather PC Enhancements

Weather PC RAM increased from 2Gb to 4Gb due to memory resource issues when running Acronis back-up software in ‘real time online’ mode, this memory increase has resolved the problem and now instead of making Incremental backups once per day, the system is creating a constant mirror of the ‘C’ drive to the second hard drive which has also been made bootable.

Hopefully these resilience measures will not be needed, but if history does repeat itself I’m better prepared than last time.

General information and status updates.

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