I have an Hammarlund HQ-100 I bought several hamfests ago. It is identical to what was my first novice receiver. I had worked a few years ago, but last New Years Eve, when I tried to use it on straight key night, the main power transformer had a meltdown.
It has no fuse, and besides the mess in the radio, the transformer needed to be replaced. Likely the filter caps as well, which may have been the original culprit, not sure. So I tried looking for a drop-in replacement, but could not find one. Some were close, but often were lacking a 5V secondary for the rectifier, or the high voltage was wrong, or the current capacities were off, etc. There also were no used ones for sale.
So I contacted Heyboer in Michigan, and thought I had agreement via email for them to build a new one. I sent them the specs, and didn’t hear back. So after a few weeks I called them, oh, he found my email. Ok, they will build it. 10-12 weeks worst case he said. After about 20 weeks, I emailed them again. No response.
In the meantime, I started cleaning up the radio. Brown gunk from the transformer and smoke were pretty extensive. Tried alcohol, acetone, elbow grease, and I improved it significantly, but could not get it all. While cleaning, I noticed two diodes soldered between a couple of the pins on the rectifier socket. Worse than that, they weren’t soldered on one pin, and on the other pin they didn’t go thru the pin at all, just tacked soldered, and the solder joint was broken. I pulled the 5U4 from the socket, and two pins were cut off, so it was just there for decoration.
I thought about repairing it using solid state diodes, which would eliminate the need for a 5V winding, but still getting high voltage specs matched were a concern. I also contacted a friend who I trust for this kind of info, and he recommended putting it back stock.
About that time, a used HQ-110 transformer came up for sale on eBay. It looked a little rough cosmetically, and it was in Columbia, the country. But the seller had 100% satisfaction rating. So I bought it, and it was less than 1/2 the cost Heyboer was quoting me.
So I’m in the process of rebuilding the power supply section of the radio. I have to replace the 5U4 octal socket, as it was gunked up. I have a new filter cap from Hayseed Hamfest. I think I will put in a 3 wire power cord and fuse. I’m not worried about originality of the power cord.
I need to test the transformer first. Then start the rest of the project. I will update as I progress through it.
