The Dummyloads

Where ham brains come to fry

Where ham brains come to fry

Archives for February 2018

Failing to Plan is Planning to Fail

Most of my parts have arrived and I am beginning the process of planning my first official scratch build.  For sure this is not a true scratch built radio like the OMs who had to learn 20 WPM CW in the 50s.  BUT my goal here is to complete a project from a schematic and learn a little about what challenges I will face in the planning phase of circuits.  I’m confident there will be LOTS of little lessons along the way….

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I Won a Tuna Tin 2

Image from www.qrpme.com

I try to attend the NORTEX QRP meeting each month.  One of the fun features of that group is that each person who attends brings some item that is excess from their junk box.  At the end of the meeting, they raffle off the items to those in attendance.  I was the first person drawn in the January 2018 meeting.  There were 2 kits to choose from.  The Tuna Tin 2 circa 2004 (link is a more modern version) and the Norcal keyer kit circa 2002.  Since I intend to build a 40M direct conversion receiver in the near future, I chose the Tuna Tin 2.  So I will hopefully make a QSO on some QRPp homebuilt gear.

Although the ultimate idea is to build and operate a homebrew transceiver while learning about radio. . . this will give me a chance to transmit a little early.

Project 1: Mission Accomplished

I said that I was going to do some homebrewing and I am.  You will see posts about that soon.  While I was waiting for parts to arrive, I have a few other projects that need to be addressed.  Project 1 is installing a Heil FS-2 foot switch for my Kenwood TS-590SG.

 

Steve — Why on earth do you need a foot switch?  Valid Question.

For the last few years I have been operating on 630M as an extension of the experimental license for KB5NJD.  As WG2XIQ/1 I’ve had a lot of fun chatting with John in the early morning hours doing CW.  Work got really busy for about a year and I got away from the habit of early morning QSOs.  Now that work is relatively sane, 630M is a real band I can operate as myself (KF5RY).  I figure not many people are on the band so I could be one of the early folks to either WAS or help someone get there.  As a result, I’m going to install an amplifier for 630M and drive that amp with my Kenwood TS-590SG.  With an external homebrew amplifier QSK is not really in the cards.  So I need a foot switch.

For my birthday I acquired the foot switch from HRO in Plano and began looking through my Kenwood box for the 13 pin DIN connector for the ACC2 plug.  I also stopped by Tanner’s and picked up a 1/4″ female jack to convert the 1/4″ jack on the foot switch to the ACC 2 connector.  All I need to do is wire it together.

After studying the manual I found that I needed pin 13 for PTT and pin 8 for ground and I’d be in business.  I studied the pins and was sure to use the mirror image as I didn’t want to get fooled by the picture translating it to my connector.  At last I took the soldering iron and wired it all up, check for continuity and went to bed feeling pretty good about myself.

Have you caught my mistake yet?

In the morning I woke up and decided to actually test the plug, in the radio.  I plugged it in and turned on the radio.  All is fine.  I stomp the foot switch and nothing happens.  I push the manual switch on the front panel and nothing happens.  I push the PTT on the hand mike and nothing happens.

I unplug the connector and plug it back in.

The radio seems to be having a seizure.  It seems stuck somewhere between ready to transmit and not ready.  There is a lot of clacking and blinking lights.  Not good. . .

After a variety of testing scenarios and tinkering, I decide that it’s not a menu setting, its something I’ve wired wrong.  So I rewire the plug on the 1/4″ jack end.  I had become concerned that somehow I had bridged the center pin and the case . . . still have a problem.  I study the manual some more.  I read about the orientation of the pins and then I realize, while it is an image of the pins from the perspective of looking at the back of the radio.  If I solder the back of the connector, it’s actually NOT a mirror image.  You just orient the connector the same as the radio and solder.  OK — I move the solder pin 5 to actual pin 8.  Should work now.

BUT I have a new problem.

The radio seems to lock into the PTT state and I cannot get it to come out of the PTT state.  I take the foot switch plug out and all is well.  I plug-in a 1/4″ jack to 1/8″ stereo adapter and the problem goes away.  . . . Why did it go away when I put the adapter in?

I take a headlamp and shine it down into the body of the female jack and it dawns on me: This is a stereo female 1/4″ jack and the male plug from the foot switch is mono.  The ring and tip are wired together in the female jack.  The 1/4″ mono plug ground sleeve is completing the circuit when the foot switch is plugged in.  No wonder its stuck in a ready to transmit state!

I take apart my wiring and cut off the ring pin all together.  It is now floating inside the body of the connector and grounded to the foot pedal each time it is plugged in.  All works FB!

All of this took about 8 hours of messing with it, testing it, trying to isolate the problem, testing it again.  Turns out I had 2 problems, but I found them!

As promised I will be posting stories of failure.  Most learning occurs when you fail.  You can only fail if you’re doing stuff.