Repairing a poorly radio receiver

My friend Brian M6BOH inherited a JRC NRD-525 receiver which at first glance seemed in good condition.

JRD-525 Receiver
JRD-525 on the bench for some TLC

However, it soon became clear that all was not well. The set could be tuned with the large tuning knob, but several keys on the number pad would not work. Closer inspection revealed that the set had met up with a cup of coffee and the encounter had not ended well for the radio.

Damage to keypad
Coffee damaged keypad

Once the radio was disassembled we could see the damage to the circuit board. With a bit of gentle persuasion some of the keys were returned to life with a stiff brush and some isopropyl alcohol, but others were beyond hope and needed replacing.

Damaged switches
Coffee has got in to several of the switches. Not all could be saved and so would need replacing.

MyGoodLadyWife agreed to do the surgery for us on this occasion and after cleaning the coffee stained area thoroughly she then removed the dead switches.

MGLW removing dead switches
MGLW gathering up the removed dead switches.

MGLW then cleaned up the circuit board ready to receive new switches. The original JRC service manual lists a part number that allowed us to buy the exact replacement part from Farnell which was lucky indeed. They were cheap too, so we bought a good stock of them in case more are needed in the future.

The switches are removed
MGLW has removed the dead switches.

Finally, the part MGLW likes best – soldering in new parts. Within a few minutes the new switches were fitted and we were re-assembling the radio ready for testing.

All repairs done
MGLW has finished the repair. Now to re-assemble and test.

So… power on, tune up and… it works! I’ll do some experiments over the next few days and post up some of the results…

Upgrading the microphone on the Yaesu FT857D

Several times a month I take part in the UKAC VHF contests on 6 and 2 meters. One of the problems I faced was that after a few minutes of calling CQ if the band was quiet, my voice was starting to get tired and croaky. I had thought about using a voice keyer, but it means extra kit to carry and provide power for when operating portable.

I recently heard about a modification you can make to the stock Yaesu microphone, by replacing the circuit board with a new one containing both a voice keyer as well as a speech compressor. This had to be checked out at once!

I ordered the “Sprach-Sendespeicher, Austauschplatine für Mikro MH31, Bausatz” (quite a mouthfull in any language) from A word of advice here – Google Translate is your friend!

Now, be warned. This is a kit of parts to assemble, not the finished product. However, the surface mount part is already soldered to the PCB. All you have to do is add the conventional components and some link wires.

Fortunately for me, MyGoodLadyWife loves to do soldering, so she was more than happy to assemble the kit when it arrived. (Lucky me!)

Here’s how the finished item looks, ready for final fitting in to a new microphone housing I bought along with the kit.

Upgrade board for FT857D Microphone
Upgrade board for FT857D Microphone

Before and After…

My local bike shop recently spent some time pampering Rose, my touring bike and while there, she was treated to a new cassette and chain. What I didn’t realise was that the middle ring on the chainset also needed replacing. How did Rose tell me this? Every time I put power down through the pedals, the chain would skip and make horrible noises. Ouch! Poor Rose…

So, out with the debit card and a bit of searching found me a replacement chain ring and the tools to fit it. Rose is a happy bike once more!
The image shows the old and new 36 tooth chains ring side by side…

Old and new chain rings
Before and after – the old and new chain rings