[Amps] Econco Tube rebuilding

[Jim Thomson]

Date: Wed, 29 Jan 2020 06:46:37 -0600
From: Rob Atkinson <ranchorobbo at gmail.com>
To: "amps at contesting.com" <amps at contesting.com>
Subject: [Amps] Econco Tube rebuilding

<Econco rebuilds external anode tubes of a certain size.  They won't
<deal with anything below around 2500 or 3000 watts plate dissipation.
<Small tubes for ham like 8877s can't be rebuilt.   You may not be
<missing much.  What I've heard is that the rebuild jobs used in
<broadcast (nowadays tube FM rigs) don't last all that long, maybe a
<year.   This is why the industry is going solid state.  The cost and
<availability of tubes is forcing them.   Fortunately for ham, tubes
<when cared for, last a long time and there are plenty of 3-500s etc.
<out there.

<73

<Rob
<K5UJ

##  Econco  indeed  rebuilds  3CX-1200A7, D7,  and  Z7. 
Its on  their list.   https://www.cpii.com/docs/related/23/Tube%20Ratings%20Data%20for%20Devices%20Rebuilt%20by%20ECONCO.pdf

##  The  above  list  is  under  section  4  of  this master  list  of  topics.     https://www.cpii.com/library.cfm/11#23   All  rebuildable tubes appear  to  be  directly  heated  types....  no  8877  etc. 

##  Talking  to  broadcast engineer  friends,  Econco  rebuilt  metal tubes  are  very  good quality.   4  years in  24/7  broadcast  use. >  35,000  hrs.  Provided  the  cathode  voltage  is  maintained 
correctly.   They  run the  fil  V  way  on the low  side...  then  fil V is brought  up  .1 V  after  XXX  hrs..to  restore emission.   They  will  also  use a Sola  constant V  xfmr,  or  similar,  to
maintain  constant  regulated  fil  V. 

##  A  ham  buddy of mine  deals  with  Econco  several  times a year.  The  rebuilt  tubes  run  like a top.   I  did  also  hear  from broadcast  engineers  who complained about  NEW  Eimac tubes
that  crapped  out  within  days.   They  were  sent  to  Econco  for a rebuild... then  ran  flawlessly in  the FM  PA...go figure. 

##  SS broadcast pa  Txs require  almost nothing  for  maintenance....  changing  out  air  filters.   Typ  setup  consists  of  10 x 1  kw  modules..and a mess  of  combiners.  If  one  module  craps  out,
the remaining 9 x modules take  up  the  slack.   The  mating  switching power  supplies are the  same deal.  And  both  can be  hot  switched....  by the janitor.  Switching supplies  operate  at > .99
power  factor..which is  superb.   KVA  from  street  to RF  power  is  typ >  92%.   Superb,  and  tube TX  cant match that...  72%  is  typ  for  tubes  operating  in  Class  C  for  FM  GG  Triode broadcast. 

##  A  lot  of  the  real  old   50s,  60s, 70s  FM  +  AM tube  txs  are  long  in  the  tooth.   Parts  are getting  harder  find in some  cases.  Like  trying  to  maintain a  mid  60s car.. that is  driven  24 /  7 /365.
Too much...down  time  = lost $$. 
Gets  to  the  point its more  cost  effective to  just  replace  it with a new  SS  unit.   Initial  install.... then  lock the  door  behind  you.   Some  of the  tube  Txs  consisted of 2 x  TXs..and a combiner. If  one
crapped  out,  you  still  had  the  2nd  unit.... and  are down  only  3db. 

## Here  in BC,  AM  broadcast  Tx  are  mostly  off  the  air....  replaced  by a spot  on the  FM  band.   And  the  spanky new FM  tx  will  be....SS. 

##  I  have  seen  Econcos rebuilt  tubes,  they  are  good  quality.  Econco  can  now  also  rebuild  chinese  and  also  Svertlana  tubes.....per the  Email  I  got  from  them a while  back...  few  months.

Jim  VE7RF