[Boatanchors] Lettine 240 Transmitter Plug In Coils

Tue Dec 14 16:16:34 EST 2010

Carl:

Have you, for years, put down Lettine as a past employer on your resume?  I 
bet every electronics firm in the US was after you once you left Lettine! 
Why even finish high school?

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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>>>>
>>>
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