Classic Japanese manufactured, 1966 Shortwave Receiver, is in need of ritual healing and spa treatments, for return to glorious sensitivity and selectivity.
Loved when you said: "Worked last time I plugged it in". Early this year my father I1BSS (91) told me: let's power the old BC312 and do some listening! Ok. So we connected it to mains and antenna and the results were not encouraging, a bit smokey to be honest. So I told him, "Well, it was supposed to be in working order!" And he: "It worked last time I plugges it in!" So I replied, "And that was.. when?" "Well... about 1993!" :)
Nice...! I had a Lafayette HA 800 once....my first receiver as a novice back in the '70's. Also had a Lafayette Electronics store in my home town as well as a Heathkit store, both about at 15-20 min bike ride from my house. Sadly neither are there anymore...! Great video on the 700...keep the videos coming!
Its good to mix it up with a new radio you know nothing about and see what they were thinking. Real Production is different from hobby mag and Handbook circuits!
I've been working on a HW-101 for weeks now and I was enjoying watching someone else clean and investigate for a while. Looking forward to the next video. Thanks again for the VFO videos you did, gave me some insight when fighting the butchered VFO in the 101
It's coming along fine. Its alive! As expected it is humming a tune now, so the caps will have to be replaced. Thanks for watching. Some of those Heathkits can drain the life out of you!
Great video! Looking for a project to get my hands dirty and relearn the basics. Now to find what would be a quality SWL receiver and get started. Thanks for your time!
excellent Mike - Looking forward to part 2....I have got to look at bringing my old KT340 back to life as it has been sitting on the shelf for many years now. I built it as a kit in 1965 but it will need some TLC and also do something about the potentially lethal power supply arrangements due to the chassis being connected directly to the (neutral or live line) ,as part of the design!
That 340 is just a year earlier, but it is a real tube chassis radio and it would be an easier radio to work with. Most would say - a better radio than this HA700. I think it has a proper power transformer, so you may be fine just checking the cord and fuse or changing it out for a modern cord.
Thanks for the detailed explanation of how the circuit sections and the filter work. I would still remove the transformer and clean the chassis from burning.
I was once told by a high school electronics teacher, who was also a service engineer and historian for the Hammond Organ company, that installing capacitors which are not close to the rated voltage of the circuit design will not reform upon power up, and fail prematurely.
The HA-700 front panel is almost identical to that of the HA-600A (the 600 has the panel in blue). Circuitry is very similar except, of course, the 600A is a transistor receiver. I got a 600A for Christmas in 1972. I picked up a second one a couple of years ago. I too scratched my head over the "mechanical" filter thing. I had big problems with the product detector in the HA-600A. It was envelope detecting and product detecting at the same time. SSB sounded awful. I eventually replaced it with a diode ring. I have details on this if anyone is interested. Has anyone else noticed this product detector problem in the HA-600A? 73 Bill N2CQR
Yes I believe that they actually tried to reuse stock parts and designs even when going from tube to solid state. Many tuning mechanisms and variable capacitors and even filters and small parts could be brought right in, thus saving scrap.
Mike, spoiling us again with another series where I can't wait to tune in for the next episode. Great video, thank you. Really appreciate your circuit descriptions coupled with background info and dry humour. I was interested to know a little more on how you cleaned the top of the chassis please - did you use just water or detergent and did you just use a brush? Very good advice about not just powering these radios up. Like you said "Worked fine last time I plugged it in"; for a few seconds until the smoke appeared.
Carefully with it propped on its side in the sink on rubber mat. Sprayed on all purpose cleaner and let it soak in. Then Hot water, dish soap and a soft brush. Rinse - drip at many angles - let it sit on paper on cardboard - selectively wipe, then hit it with the hair dryer. Not perfect, but settled the dust without total baptism and harsh chemicals. I was careful to try and avoid the dial string and front panel. Lube and grease and contact cleaner later.
I assume the transformer is blown? Can you find a replacement? Looking forward to Part-2 for this repair. Thanks for sharing it with us. 73 de K7RMJ.. Frank
I also wondered about possibly having to replace the mains transformer. I used to do a little valve (tube) radio restoration. If I suspected the mains transformer was blown, I would not buy a set. Even if the transformer is a fairly standard design, they were often made for the set. So, even if you find one with the right windings, chances are it will be different dimensions. Also, many items of equipment had "oddball" additional windings like the LT secondary for the mixer tube in Mike's example. So, you maybe ended up, if you could, installing 2 or even 3 transformers to replace the original. All in all, most problems can be fixed fairly easily, except finding just right mains transformer. Of course you can get them custom made but last time I checked, it was very expensive.
@@Steve-GM0HUU It actually is a replacement. Lafayette's factory Depot was located very close to where the radio was purchased on Long Island. I personally know the owner and have the story which I will cover.
Some yaesu also had the transformer problem likely due to bad quality of transformer iron causing excessive heating. Also better check the heater voltage. anything above 6.3v is bad for tube life. Usually it is 6.6 to 7v due to higher mains voltage compared to its design voltage of 110v
Little Jonny with his new radio is having fun till he tried to burn the house down! I actually know the exact provenance and owner of this receiver. All will be revealed.
Why did they not use the Wire -Ended Philips/Raytheon low voltage vacuum tubes and make it that you had to use headphones (Cans) or an addon Amplifier with speaker for listening without Headphones and it would be more compact.
