Tuesday, March 12, 2013

Heathkit HW-8 Update

Heathkit HW-8 with Headphones and Code Key
The Heathkit HW-8 QRP Transceiver I bought on eBay arrived safe and sound. It was well packed with the original box inside. The radio is very clean and has had no modifications done to it. It seemed to be basically working out of the box. It included the original manual with fold out schematic and pictorial pages. It even came with one of the two original plastic alignment tools!

Original Box, Manual, and Alignment Tool

According to a hand written note in the manual some the front end toroid coils were assembled incorrectly (in the wrong locations). Looking at the manual and the radio confirmed it. It also appeared to be not as sensitive on the 3.5 and 7.0 MHz bands as it should be. I removed the toroids (which was quite a job as the PCB needed to be partially removed to get at them) and reinstalled the coils correctly. Someone had installed an extra capacitor on the bottom of the PCB across 40M trimmer cap to compensate for the inductance of the wrong coil; I removed that too.

Top Cover Removed Showing PCB
The mystery is, who figured out that the toroids were wrong - the original builder or someone later? Kudos to whoever figured it out, but why didn't they fix it? Anyway, after 30 plus years the radio is now working as it should.

Rear Panel
After the fixes and doing a full alignment it seems quite sensitive on all bands. It is quite selective when set to Narrow selectivity, good for situations when there are several nearby CW stations being received. It is simple to operate and while it isn't full break-in, it is pretty close.

Front Panel
As I speak, it is on the bench and receiving a very strong signal from W1AW's evening code practice on 40 meters. I'm looking forward to trying it out on the air and seeing if I can make some contacts. I'm also planning to do an in-depth YouTube video about the radio.