[Drake] Drake L4B/8877 Retrofit Revisit

[w2cqm@juno.com]

Drake L4B/8877 Retrofit Update

You may recall that there�s a chilling bit of dialogue in the classic
movie Poltergeist that�s particularly memorable and somewhat  related to
this posting.  It�s the scene when the little girl announces ("...They�re
back!")  that the hated spirits and goblins, which were thought to be
exorcised, had returned. I guess the same can be said for me (I'm back)
and not unlike General McArthur, I  too have returned with a L4B project
that on one hand  created heated discussions,  a full range of support
for the project, and of course on the other extreme the inevitable, 
inane hate mail.  
I initially vowed to myself that I�d never  undertake a similar project,
based primarily on the amount of labor involved. However,  I did almost
immediately thereafter change my mind simply because I realized from the
experiences with the first project that  I could easily and more quickly
duplicate a powerhouse amp in the �vintage lady� and further refine the
endeavor. There�s something to be said for success and its effect on
one�s ego. 
	As many of you may recall, the completed  project netted a certified
1800watts into the dummy load as verified by a pair of Bird 43/4410
wattmeters. Although the tube had power to spare, the selection of the
plate transformer needed some additional thought.  At that time, the
selected  transformer provided a  limited voltage output under severe
load.  Since I knew I could better, I began planning a new Drake L4B
redesign  powered by a Peter Dahl Hypersil and a downsized rectifier
board package rated at 4000VDC @ 2 amps. 
	The construction parameters remain the same both for Drake as well as
similar projects I undertake with other brand amplifiers.  No exterior
changes were ever  considered  on my retrofit that would suggest other
than the classic  OEM  deck resided within the enclosure. . Refinement
would be  restricted to the interior of the cabinet. The remote power
supply was of necessity to enjoy a  complete redesign  including new
cabinetry for the obvious reasons. The major problem that confronted me
on this as well as the two previous undertakings was locating a mint
Drake deck. I can tell you with a high degree of authority that finding
one  was more easily said than done. I posted wants on the various
reflectors, searched eBay for over 6 months, and even visited the Tuesday
evening Drake Net and with trepidation  stated my needs. No response!
Since I was unsuccessful at the outset, I decided to work the project
backwards. I built the power supply first incorporating some refinements
to the interior circuitry. All was going well with that aspect except the
 Drake remained conspicuous by its absence.   I decided on another tactic
that included prayer, self flagellation, fasting, abstinence, and  even
voodoo with hanging chicken legs and special feathers. To no avail!  Then
my luck changed quite suddenly.. A kindred spirit, Sam, N9EMZ appeared on
the scene. He was a self assured, ardent Drake collector who (in spite of
a clear recollection of my previous experiences with a group of  Drake
zealots  and what they considered I was doing to be sacrilegious) 
offered up an absolute mint deck for the adventure that was to certainly
to follow. The price  for and the  condition of the Drake  was far better
than I could have ever anticipated. I think I could have better faced the
bad mouthing that would certainly follow if the amplifier had been a
basket case. But I mention honestly that secretly  I was ecstatic. 
Things were finally  looking up. And for the first time in my life I felt
that I truly had won a great prize. In any event, Sam hand delivered the
amp to the Dayton  motel to make absolutely certain that it would arrive
in pristine condition.  He even insisted that he carry it into the room. 
We talked, compared notes about  common interests, solved some of the
problems of the world and then off he went for some rest before the doors
opened at the Dayton Hamfest on Friday.  I�ve been staring at the L4B
since then. Tomorrow, it�s going on the bench for first stage of the
reconstructive surgery. I�ll be removing the tubes, sockets, chimneys,
filament transformer, HV choke, parasitics, plate caps,  fan, ALC board
and accompanying front panel ALC switch, antenna changeover relay and
other sundry  items.  What I plan to do is document the step by step
process and include annotated digitals on my web site. I suspect that at
least several of you may want to duplicate the effort when it�s up and
running over 2kw and that information will prove to be a resource that�s
easily accessed.  I�m a retired educator and college professor whose
specialty was training individuals to be effective vocational classroom 
teachers. Preparing and delivering complicated hands-on  subject matter
to youngsters in a non-intimidating  environment was what I did best. I�m
certain you�ll find it worthwhile, easy to read, and well within the
range of the individual  with even a moderate skill level. 
 In the interim, let me know if you can use some of the removed
components to get your gal up and running. They�re up for grabs and the
money I receive will help defray the cost of the project.  Don�t hesitate
to contact me provided   you have other than nasty comments to share. The
others with venomous key strokes can direct their perspectives to Sam,
N9EMZ who graciously volunteered to take the brunt of the heat.  Will
keep you abreast of the progress. 73�s Ron W2CQM/3


Epilogue: visit  www.QRZ.COM/W2CQM for a listing of the  most recently
authored  amateur radio  related articles by W2CQM.