[Boatanchors] Lettine 240 Transmitter Plug In Coils

[Carl]

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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