[Drake] L4B plate voltage

[John King]

----- Original Message ----
From: "Singley, Rodger" <rbsingl at ilstu.edu>
To: John King <k5pgw at yahoo.com>
Sent: Sun, December 20, 2009 9:20:16 PM
Subject: RE: [Drake] L4B plate voltage

Hi John,

Based upon the other responses my no load voltage sounds a bit high but the metering circuit in the L-4/L-7 is probably +/- 10% at best.  I am pretty certain about my line voltage since my Simpson and Tektronix DMM's are both in agreement but I am just relying upon the built in metering circuits in the Drake amps.

What is your plate voltage running?  If it is truly low suspect the filter caps; I replaced them in both of my power supplies.  The bleeder resistor in the supply puts a whole lot of heat in the power supply case-especially in standby in the SSB position.  It is likely your filter caps have been cooked over the years.

The L-4B and L-7 use the same power supply but I much prefer my L-4B to the later L-7.  The only advantage the L-7 has is 160 meter coverage but it uses a fan cooling system similar to the Heathkit SB-220 instead of the nice blower/chimney system of the L-4B.  Of further oddity is that if you use them on AM the difference is more important since the T-4 series uses a linear amp friendly controlled carrier system while the TR-7 series is full carrier.  I check into a local 160 meter AM net and run the L-7 at 150 watts carrier out and it gets very warm in a hurry.

73 and Merry Christmas!
Rodger WQ9E


-----Original Message-----
From: John King [mailto:k5pgw at yahoo.com]
Sent: Sun 12/20/2009 8:59 PM
To: Singley, Rodger
Subject: Re: [Drake] L4B plate voltage

Thanks Roger, that is what I needed to know.Ii measured 123 volts each side with a Fluke. Now I will take a closer look at my power suopply voltage. 73, John, K5PGW



----- Original Message ----
From: "Singley, Rodger" <rbsingl at ilstu.edu>
To: John King <k5pgw at yahoo.com>; Drake at mailman.qth.net
Sent: Sun, December 20, 2009 6:51:59 PM
Subject: RE: [Drake] L4B plate voltage

John,

For mine 2100 CW/Tune and 3000 SSB and my L-7 shows virtually the same.  Line voltage is 237; I assume you are measure 123 on each side so if your AC voltmeter is accurate your line voltage is up there.

Rodger WQ9E


-----Original Message-----
From: drake-bounces at mailman.qth.net on behalf of John King
Sent: Sun 12/20/2009 6:43 PM
To: Drake at mailman.qth.net
Subject: [Drake] L4B plate voltage

Can anyone on the reflector, who has an L4B, tell me what they read on their plate voltage meter with the power supply plugged into 220 vac and turned on? Also does anyone know if the voltage multiplier resistors  age and change value with time to the point that the Heath SB 220 resistors do? Anyone had trouble with that using an L4B?

I have 223 on each side of my 220 line in the shack. I would appreciate knowing what plate voltage your L4B has. Thanks for reading and 73, John, K5PGW



      
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