02-11-2015, 04:42 PM
The HMV radio project has come to a successful conclusion. It is now up and running on my boat. Over the weekend I'd been concerned about my dim-bulb-lamp giving out an orange tint which isn't a usual scenario when I power up a radio. I'd also had major concerns over one of the H.T. Smoothing cans. After some high voltage testing on this can in isolation, I decided to remove it from the circuit. I then made a few tests of just the rectifier and H.T. supply before going through the rest of the radio with a fine toothed comb.
Of course, testing on my boat is a cramped affair. I have to use the bed as my test bench and I lay out a big wooden board. The speaker is contained in another part of the radio so I just connect the speakers up with terminal blocks for now.
Anyway, after a few unsuccessful attempts, I finally managed to get the cricket coming in loud and clear. In fact, it's working very well at this point although I still have a few modifications to do yet. Voltage on the output tube was O.K. No sign of excessive current draw.
I believe the whole strategy of soldering around the small ladder was a good way to go because this is actually tied to the chassis by multiple component connections which would be easy to confuse on re-assembly. So, as I stated before, I soldered stiff cable at the reverse of the ladder and looped it around to the front so each capacitor would be brought forwards as it were. I was using my usual "cheap and cheerful" big red Wima capacitors and some yellow spragues.
I imagine this radio hasn't worked for possibly 20 years. It was a fair bit harder than your usual attic stored radio as it had been exposed to a good deal of damp and cold in a farmers barn. When I started work on it even the mains power fuse-holders were O.T. due to corrosion.
I enclose a small pic. I wouldn't worry too much about the scorch marks as I can better insulate this later and tidy things up a bit more.
Of course, testing on my boat is a cramped affair. I have to use the bed as my test bench and I lay out a big wooden board. The speaker is contained in another part of the radio so I just connect the speakers up with terminal blocks for now.
Anyway, after a few unsuccessful attempts, I finally managed to get the cricket coming in loud and clear. In fact, it's working very well at this point although I still have a few modifications to do yet. Voltage on the output tube was O.K. No sign of excessive current draw.
I believe the whole strategy of soldering around the small ladder was a good way to go because this is actually tied to the chassis by multiple component connections which would be easy to confuse on re-assembly. So, as I stated before, I soldered stiff cable at the reverse of the ladder and looped it around to the front so each capacitor would be brought forwards as it were. I was using my usual "cheap and cheerful" big red Wima capacitors and some yellow spragues.
I imagine this radio hasn't worked for possibly 20 years. It was a fair bit harder than your usual attic stored radio as it had been exposed to a good deal of damp and cold in a farmers barn. When I started work on it even the mains power fuse-holders were O.T. due to corrosion.
I enclose a small pic. I wouldn't worry too much about the scorch marks as I can better insulate this later and tidy things up a bit more.
