[Boatanchors] Lettine 240 Transmitter Plug In Coils

[LEE BAHR]

Carl:

What did you tell Lettine when you quit?  Did you tell them these things 
"aint no Collins"?   I'd be interested in some of your stories or nighmares.

Lee, w0vt


>>
>>> Ah, the infamous Latrine 240. I spent many afternoon and weekend hours 
>>> as
>>> a HS student helping to assemble those TVI generators for a most nasty
>>> and
>>> ungrateful pair of owners. At least they were in my home town and I 
>>> could
>>> ride the bike there in about 15 minutes. I quit after about 3 months and
>>> positively burnt the bridges behind me!
>>>
>>> Carl
>>> KM1H
>>>
>>>
>>>
>>>
>>> ----- Original Message ----- 
>>> From: "LEE BAHR" <pulsarxp at embarqmail.com>
>>> To: <boatanchors at mailman.qth.net>
>>> Sent: Tuesday, December 14, 2010 2:15 PM
>>> Subject: Re: [Boatanchors] Lettine 240 Transmitter Plug In Coils
>>>
>>>
>>>> As I mentioned earlier, the Lettine is a rats nest under the chassis.
>>>> Everything needs to be replaced including the AC line cord.  The
>>>> transmitter
>>>> was modified to include a changeover relay which is also in a rats nest
>>>> fashion plus much of the cloth wiring looks like it could stand
>>>> replacing.
>>>> Combine this with the fact many of the tie points have no lugs but are
>>>> just
>>>> "free in the clear floating connections", I decided I will "strip the
>>>> chassis down and start over.
>>>>
>>>> I ordered all new caps and resistors plus a 3 prong power cord 
>>>> yesterday
>>>> from Mouser for the re-construction.  Lettine placed some of the parts
>>>> in
>>>> some really strange places.  Because of this,  I am not sure I want to
>>>> remove everything at once and then start over or just replace 
>>>> everything
>>>> section by section.  I am inclined to do it the later way as the wierd
>>>> parts
>>>> placement at times plus the lack of tie lugs, which I plan to add, lead
>>>> me
>>>> to believe I can keep parts placement closer to original specs if I do
>>>> it
>>>> section by section.  I'll probably start with the power supply and then
>>>> move
>>>> on to the oscillator and then to the final.  Once the RF is working,
>>>> I'll
>>>> move on the to audio input and modulator stages.  The only problem 
>>>> doing
>>>> the
>>>> restoration this way is it is going to be harder replacing point to
>>>> point
>>>> wiring.  (I think I need to take a few pictures of it as it now stands
>>>> in
>>>> case I run into trouble.  I am a little nervous of using the BAMA 
>>>> manual
>>>> as
>>>> it was "re-drawn".  (I already found three small mistakes in the BAMA
>>>> re-drawn schematic).
>>>>
>>>> When ordering the new parts,  I ordered much larger wattage resistors
>>>> then
>>>> the originals to make the new parts closer in size to the originals as
>>>> many
>>>> new parts of the same wattage are much smaller today.  Instead of 8 mfd
>>>> filtering I will have 16 mfd of power supply filtering.
>>>>
>>>> The plate choke and parasitic supressor as original are a real joke.  I
>>>> am
>>>> seriously thinking of putting in a real multi-pi RF choke feeding the
>>>> 807
>>>> plate and also put in a more standard parasitic supressor on the plate
>>>> lead.
>>>>
>>>> As it stands, this is a real complicated restoration when you consider
>>>> this
>>>> is a simple transmitter with not too many parts.  The unorthodox 
>>>> layout,
>>>> bad
>>>> wiring job, lack of tie points and rotted wires all make the 
>>>> restoration
>>>> difficult more difficult.  Once restored, the bottom chassis will look
>>>> very
>>>> unencumbered and look like it was a piece of cake to restore.
>>>>
>>>> Then, comes the restoration of a plug in coil set for this transmitter.
>>>> This is a "cool" kind of rare transmitter.  If it were not for it's
>>>> great
>>>> outside appearance, the time spent restoring this transmitter could not
>>>> be
>>>> justified.  When finished it will be a jewel, but you could never get
>>>> your
>>>> time and money out of it if you ever would want to part with it.  I 
>>>> know
>>>> this going into the restoration.  As I mentioned earlier,  a WRL Globe
>>>> Scout
>>>> 40A looks like a Collins internally compared to this rigs guts.  The
>>>> Lettine
>>>> cabinet, front panel and transformers were all first class.  From that
>>>> point
>>>> on it was all downhill.
>>>>
>>>> Lee, w0vt
>>>>
>>>>
>>>>
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>>>
>>
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