[time-nuts] LAVOIE LA-800D WWV Timebase Receiver

Joseph Gray jgray at zianet.com
Mon Dec 21 05:09:28 UTC 2009


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 <bill at iaxs.net> 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 bill at iaxs.net
>
> -----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
>
>
>
>
>
>
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