Did you turn on the receiver before you hooked up the three PTO wires? As I
remember, there is a tantalum cap that can BLOW if the PTO wires are not hooked
up. As I remember the low voltage for the PTO derives from a high voltage
point and if you have "no load', the dropping resistor doesn't drop the voltage
and the low voltage cap then goes BANG. If the cap goes and shorts out due to
excessive voltage, the dropping resistor could burn up from the cap blowing up.
Lee, w0vt
----- Original Message -----
From: George Roberts
To: drakelist@zerobeat.net
Sent: Sunday, March 15, 2009 7:11 PM
Subject: [Drakelist] No signal on R-4C after work on PTO
Dear List,
I've been reading the mail in this site for a long time, with much
appreciation for the knowledge and willingness you guys have to share it with
the folks. This is my first input and question:
No signal after cleaning PTO Drive on Drake R-4C as per instructions on the
K4OAH site. I first cleaned bearing and shaft on preselector. Cleaned switches
and tube sockets and pins. Tested tubes with my Jackson Dynanic 648S Tube
Tester. Had to disconnect 3 wires (red, brown and white) on PTO to work on
drive. Re-connecting PTO wires to PWB #2, the white went to the pin next to the
ground lug, the Brown to the pin just above the white, and the Red to the right
of the Brown. After putting it all together, I get noise that I can peak
ABNORMALLY with preselector as follows:
Band Switch Slugs
1.5-3.0 Can't peak
3.5 6/64"
7.0 1/32"
14 Can't peak, louder with slugs at bottom
21 Can't peak
28.5 Can't peak
but no signal.
.
Connecting freq counter to INJ jack gives no reading. Connecting to shielded
cable leaving PCB 2 after adjusting disks, reading at 500 is steady 4994.8 Khz.
Reading at 0020 (can not go lower because the slug is at its outer limit) is an
erratic 1395-1540 Khz.
Does any of this make sense? Note: I did not "adjust" any trimmers!
Serial number is 20620 and uses 6HS6 instead of 6EJ7 in premixer and 1st
mixer. My schematic shows 6EJ7's.
Wondering if the pinouts are the same?
My test gear consists of a 20 Mhz scope, Precision E200D RF Signal Generator,
Victor VC 3165 frequency counter, a DMM and VTVM. I don't have much successful
experience trouble shooting, so I'm asking the esteemed panel on this Drake
website if there is any hope for my R-4C. Thanks much and best 73.
George K2HRS
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