[AMRadio] Broadcast transmitter


John Wright n1fcu at yahoo.com
Fri Apr 21 19:53:25 EDT 2006


I have an rca bta-1r (just got it) and I wonder how
much drive you need for the circuit as you have it?

John (N1FCU)

--- "KC8OPP Roger S." <kc8opp at yahoo.com> wrote:

> Rick,
> 
> Here is what I did to bring the RCA to 160/80/40M.
> 
> First thing is get a copy of the "Radio Handbook" by
> William Orr, W6SAI.  This book has all the answers.
> 
> I started by bringing the transmitter up on the freq
> the radio station used.  I cleaned and repaired as
> required.  I checked all voltages against the book,
> swept the audio section and made more repairs.  When
> it works as advertised by RCA, then you can start to
> have fun.
> 
> I removed the master osc board and built a box for
> the
> grid input circuit.  I used link coupled coils that
> are switched in for each band and drive the grids
> with
> a Kenwood TS-520.  The same band switch is used to
> changed the taps on the final tank coil.  The
> winding
> data for the grid coils was borrowed from the 16th
> edition of the Radio Handbook.  I did install a grid
> coil for 20M, but have never tried the transmitter
> on
> 20M, wishful thing I guess.
> 
> The final tank that RCA installed was completely
> removed and I used the "L" coil for my tank.  Vac
> variable caps were used for Tune and Load.  I put
> the
> circuit together on the bench to find the right taps
> on the coil.  Use a non inductive resistor in place
> of
> the tube that is equal to the calculated plate load
> and then a antenna analyzer connected to the output.
> 
> This put me in the ball park and just some minor
> changes were needed when the tank circuit was
> installed in the cabinet.
> 
> The cabinet measured 32 inches deep and 34.5 inches
> wide when I removed the meters and switches, just
> enough room to fit through the doors.  I would guess
> that in the stripped down mode the cabinet still
> came
> in around 300 pounds or so.
> 
> Hope this helps a bit, I will look forward to
> hearing
> your RCA on the air.
> 
> 
> Good Luck and 73's
> Roger
> KC8OPP
> 
> 
> --- Rick Brashear <rickbras at airmail.net> wrote:
> 
> > Wow!  Thanks Roger.  Great pictures documenting
> the
> > move and 
> > restoration.  I would be very interested in the
> > modifications you made 
> > to the tuning circuitry.  At this point I only
> plan
> > on having mine setup 
> > for 75 meters, but it is nice to know someone who
> > has successfully 
> > modified one to accommodate 160, 80, 40 and 20 in
> > case I want to expand 
> > the coverage.
> > 
> > Could you tell me exactly how wide the cabinet was
> > after you removed the 
> > meters, switches, etc.?  I'm afraid I'm going to
> > have to back my truck 
> > through the side of the house to get mine inside! 
> > Also, how much do 
> > suppose it weighed when all of the iron, doors and
> > everything else 
> > removable was removed?
> > 
> > Thanks for sharing your story, pictures and
> > expertise.  I can hardly 
> > wait to get started on mine.
> > 
> > 73,
> > Rick/K5IZ
> > 
> > 
> > KC8OPP Roger S. wrote:
> > 
> > >Rick,
> > >
> > >I have a BTA-1R that is set up for 160/80/40M. 
> > Here
> > >is a link to some pictures of the process.
> > >
> > >http://photos.yahoo.com/kc8opp 
> > >
> > >If I can help in any way let me know.
> > >
> > >Good Luck.
> > >
> > >73's
> > >Roger
> > >KC8OPP
> > >  
> > >
> > >  
> > >
> > 
> > 
> >
>
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