Menu

Problem with National NC-57

Search this Thread

Prev

Previous Post

Next Post

Next

#2

Report Post

Old

January 28th 08, 07:26 PM posted to rec.radio.amateur.boatanchors

Don Bowey

Don Bowey is offline

external usenet poster

First recorded activity by RadioBanter: Jul 2006

Posts: 286

Default

Problem with National NC-57

On 1/28/08 9:37 AM, in article
, "N4JOY"
wrote:

Hi -- I recently completed some repair work on a National NC-57. I
did the typical replacement of electrolytics, out of tolerance
resistors, etc. It was functioning reasonably well beforehand but was
in need of some TLC. Following my repair work, I turned the unit on
and am only receiving a hum with no RX. I conducted some resistance
measurements at all tube sockets and every measurement was nominal
(according to my NC-57 manual) except for pin 6 of tube 7 (6V6GT).
The manual indicates a resistance reading of 380K ohms and I'm
receiving around 50K ohms (same as pin 3 and pin 4). To be honest, I
can't see how pin 6 should be 380K ohms. The output transformer
primary shunt resistor is 22K ohms and everything is wired correctly
at the tube socket. I double checked my work and carefully reviewed
the schematics -- everything looks good. I'm really stumped here...

Any help would be greatly appreciated!

Chris, N4JOY

There is either a wiring error or a defective component. Pin 6 of the tube
socket is not used by the tube, so it is obviously used as a tie-point.
Trace in both directions from pin 6 and you should find the problem.

Hmmmmm... Are you certain that each tube is in it's correct socket?

Reply With Quote

Reply With Quote

Thread Tools	Search this Thread
Show Printable Version	Search this Thread: Advanced Search
Display Modes
Switch to Linear Mode Switch to Hybrid Mode Threaded Mode

Posting Rules
Smilies are On [IMG] code is On HTML code is Off Trackbacks are On Pingbacks are On Refbacks are On

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
What's the problem?	AB8MQ	Policy	1	October 5th 05 11:05 PM
Haynie admits to problem, alzheimers victims respond with, "What problem?"	John Smith	Policy	111	June 23rd 05 01:55 AM
FA: NATIONAL NC-270 HAM RECEIVER - ONE THE LAST NATIONAL BUILT	Biz WDÃ˜HCO	Boatanchors	0	December 3rd 03 10:16 PM
National NCX-5 transmit/receive offset problem	Chris	Equipment	2	July 19th 03 02:57 AM
National NCX-5 transmit/receive offset problem	Chris	Equipment	0	July 17th 03 05:29 PM

All times are GMT +1. The time now is 09:07 PM.

About Us

"It's about Radio"

Contact Us RadioBanter forum home Privacy Statement

Copyright © 2017