The Importance of the Right Washer October 27th, 2013
We recently had a puzzling service problem. The customer had an Elecraft K3 which we built for him some six months ago. He then decided that he wanted to add a voice recorder module. This is not a terribly complicated task, but does involve removing the front panel. Unlike other radios, the K3 front panel can easily be pulled forward and in our service department it is a job that only take a few minutes. Then it is a case of removing the DSP board from the back of the front panel in order to install the voice recorder.
The owner of the radio had decided to do this work himself, but when the work was completed the voice recorder failed to work and the received audio was intermittent. The classic error of doing this job is to fail to use the insulated plastic strew to fasten the voice recorder. A standard metal screw can cause a short or an intermittent problem. But the owner had checked this and all looked fine. He had even gone back through all his work and still no cure. Even the removal of the voice recorder now did not bring the radio back to normal. It still had the audio problem.
It was agreed that we should collect the radio from him. The first thing we did was to replace the entire front panel to make sure that the problem was in this area, It was! We took the original panel and removed the voice recorder, but this did not help. The next suspect area was the DSP board. We removed this and decided to swap this board for a new one. The voice recorder is mounted on this DSP board via a metal post. Whenever we take things paart like this we always do it over a plastic tray to catch any small items that might otherwise roll across the bench and onto the floor. As we took the post off, onto the tray fell an inside toothed washer, This is larger than the normal split pin washer that should have been fitted. We then looked at the board and it was immediately obvious that this slightly larger washer had shorted across the track and was the cause of the problem. It had done no harm and as soon as the correct washer was installed, everything was back to normal. So it was not the voice recorder that had caused the problem, but the mounting of the support post. Another problem solved and another happy customer. Peter G3OJV.