I'll have to agree with Bill's good advice. I often have people ask me about some old tube radio that "Grandma" used to have. I always tell them to not plug it in to see if it still works.
With any piece of equipment from the tube era, you can bet that as a minimum, the electrolytic caps need replacing. Only after that is done do I even try to power it on, and even then, I use a variac. To do things right, all the paper caps should also be replaced. Then it is a matter of checking other components. Old resistors like to change in value over time. As Bill said, don't burn up a vintage piece of equipment. Once the magic smoke gets out, you'll never get it back in again. Joe Gray KA5ZEC On Sun, Dec 20, 2009 at 9:53 PM, Bill Hawkins <[email protected]> wrote: > Dave, > > Please, folks, don't just turn on a piece of vacuum tube equipment. > That could burn out an irreplaceable power transformer. If you do > not have equipment to test for shorts or bad electrolytics, then > make a jig with a light bulb socket to put the bulb in series with > the line. Start with a 40 watt bulb (CFLs won't work) and work up. > If the bulb is always bright, don't apply line power to the set. > > I sold my LA-800 last spring. Don't remember what paper went with it, > but I had the schematic at one time. Sadly, my "filing" system does > not make it possible to retrieve anything without going through all > of the paper collected over 25 years. Try Manuals Plus. > > The standard input on the left of the panel feeds selected multipliers > that produce 10 MHz. This is fed to a phase shift network such that > the scope produces a circular sweep at 10 Mc (circles per second). > Sounds like the horizontal scope amp is dead, if you supplied a local > standard signal and the multipliers worked. The 90 deg phase shift only > produces a circle at 10 MHz. > > The WWV section on the right side only receives 5 or 15 MHz. Some magic > is used to get 10 MHz out of either carrier. This is used to intensity > (Z input) modulate the circle. Dunno why they don't receive 10 MHz. > > Several years ago, here in MN, I had an HP-103 as the standard and was > listening on 5 MHz. Propagation was such that WWV would alternate with > the female voice at WWVH. The bright half of the circle would change > sides, illustrating the phase shift with distance. Neat stuff. > > I'm willing to help you get this fine receiver back in action. > > Nice workbench. > > Bill Hawkins [email protected] > > -----Original Message----- > From: Dave > Sent: Sunday, December 20, 2009 4:03 PM > > Hi Timenuts, > > My first email to the list. I've had this LAVOIE LA-800D (see picture) > receiver for about 10 years now. Before that, it was sitting in an > ariplane hanger for some unknown number of years and was headed for the > trash when I aquired it. Well, I finally put it on the work bench and > was quite surprised that I was able to power it up without anything > exploding. I've determined that it will receive WWV on 5mc quite well > and produce a vertical deflection on the scope. I can hear a very weak > 400hz on the speaker. I can also feed 400 kc into the local standard > input and see it getting filtered and amplified internally. This is a > far as I can get. I am not sure how this device is suppose to work but > am fairly certain that most of it is functional. I really need to find > schematics and some operating instructions to make it work all the way. > I've already done the quick google and other customary searches for info > without avail. If anyone out there could email me pdf's of the > schematics, and other manuals it would help me a lot in getting this > classic piece of equipment back in operation. Pointers to info would > also be appreciated. > > Thanks, > > Dave > > > > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
