[Drake] L4b/L7 power supply rebuild??

[Jim Garland]

Hi Dave, You can buy a recapping kit for the L4B from Harbach Electronics
(http://www.harbachelectronics.com/main/page_products_drake_l4l4bl7.html ) .
Depending on how much work you're prepared to do, you could also add a soft
start circuit, also from Harbach. You can also find a different kind of soft
start circuit on my website at
http://www.w8zr.net/vintage/amplifiers/Drake%20L4B%20Modification/Drake%20L-
4B%20Modification.htm

 

I've recently installed the Harbach power supply upgrade and was quite
pleased with it. Very straightforward to install. Haven't used his soft
start circuit, since I used my own. Mine takes about two hours to install.

 

The L4B power supply normally runs rather hot, especially in the SSB mode,
because of the heat dissipated in the bleeder resistors.

 

73,

Jim W8ZR

 

  _____  

From: drake-bounces at mailman.qth.net [mailto:drake-bounces at mailman.qth.net]
On Behalf Of Dave Edwards
Sent: Monday, January 19, 2009 6:38 PM
To: drake at mailman.qth.net
Subject: [Drake] L4b/L7 power supply rebuild??

 

Can someone help me out?

Unless I'm confusing this for the transceiver power supply rebuilds, didn't
I see a filter board or caps or something like that to rebuild the L4 and L7
series Drake supplies?

 

Turned on my L4B today and the supply sure smelled like something
frying....and got fairly hot without even transmitting. Nothing popped, but
I shut it down. Could have just been dust or bugs?? since it sits close to
(but not on) the ground in a basement shack. Has not been on for about a
year and a half!!

 

I figure even if all is well, how old must those caps and high voltage parts
be???   Probably could use a "once over" 

 

Thanks for anyone's input!!

 

....Dave

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