Re: [AMRadio] Seeking tubes

2005-07-08 Thread Donald Chester 



Is the 849 about 10-12 high with the same type of pins? Looks about
the same but no 'necks'? If so, I have a well used one still in the
wooden crate and another with a case of the rattles (filament ist
kapoot, methinks). Might consider trading one for a 204


The 849 is similar, but bigger than the 204A.  It's the predecessor to the 
833A.  The RCA book says the 849, 204-A and 851 should all be mounted upside 
down so that the filament is up and the plate down.


I have run into a couple of hams on the air running 204A's.

The old pre-WW2 kilowatt RCA broadcast transmitter ran four 204A's in 
pushpull parallel, with a pair of 849 modulators.  Later, they changed to a 
pair of 833A's modulated by another pair - and even sold a modification kit 
to convert the older transmitter to 833A's.


Those older tubes were always expensive.  Back in the mid 30's, a 204A sold 
for about $85 - the equivalent to hundreds of dollars in today's money.  The 
newer 833(A) sold for a fraction of that.  That's why BC stations were 
interested in retrofitting their transmitters.


In the mid 70's I ran into about a dozen Amperex 849A's piled in a cubby at 
Young Engineering in Salem MA.  I couldn't get the guy to reduce his price; 
he wanted about $20 each for them, as is.  No way to test them, but they 
looked good.  I turned him down, and later, they apparently all got broken 
as they shuffled stuff around in the old warehouse.


I still kick myself for not taking a chance on those tubes.

Don K4KYV

Re: [AMRadio] Heath SB Problem!

2005-07-08 Thread Ed Swynar 
Good Morning Bob,

Ah yes, the very infamous friction drive disk --- surely *THE* Achilles heel
in the otherwise excellent SB-series from Heath...

Some years ago a chap posted a description of his own homebrewed version of
a direct REPLACEMENT for that contraption --- I wish I could recall his name
 address, as I do believe this could very well grow to be a nice little
cottage industry for the enterprising entrepreneur within our ranks...

Let's face it: unless your rig is simply sitting pretty atop some display
case strictly for show, ALL those friction drives wear with time in an
active station, they do need periodic re-adjustment / maintenance, and
sooner or later need to be replaced outright. I only just wish that I was
smart enough to come up with a viable, marketable alternative myself...!

BTW, there are several entries in vintage HINTS  KINKS on this very
subject matter --- have you researched those yet...?

~73!~ Eddy VE3CUI - VE3XZ


.


- Original Message -
From: Bob Macklin [EMAIL PROTECTED]
To: Discussion of AM Radio amradio@mailman.qth.net
Sent: Thursday, July 07, 2005 6:24 PM
Subject: Re: [AMRadio] Heath SB Problem!


 Dennis,

 This afternoon the dial stopped turning when I turned the knob. I have
been
 through this before. But this time I could not adjust it. I had to
 disaaemble the Bezel and get the input shaft out. One of the spring disks
 that form the friction drive has broken.

 I have contacted RTO about a replacement. I hope they have them. I am now
 going to pull the chassis out and see if I can find the broken piece. If I
 can find it I might be able to fix it.

 Thanks,
 Bob Macklin
 K5MYJ/7
 Seattle, Wa.

 REAL RADIOS GLOW IN THE DARK

 - Original Message -
 From: [EMAIL PROTECTED]
 To: amradio@mailman.qth.net
 Sent: Thursday, July 07, 2005 4:16 PM
 Subject: Re: [AMRadio] Heath SB Problem!


 
  In a message dated 7/7/05 3:22:37 PM, [EMAIL PROTECTED] writes:
 
 
   Is anyone here familiar with the LMO drive on a Heath SB unit?
  
  
  BOB,
 
  I've been into the one on my SB-300.   What's the problem/question?
 
  Dennis D. W7QHO
  Glendale, CA
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