[ARC5] BC-455 not working

[J Mcvey]

'I have already restored a BC-454 and aligned it. So that is not a problem. I have sig gen, frequency counter, and scope. 
When I inject the 2830khz signal, where do I check to see if the IF is picking it up?''
That begs the question: How did you align the BC-454 ? The procedure is exactly the same! 
Remove the 12K8 grid  cap, inject the modulated IF frequency ( at the lowest useable amplitude), start with the second IF and work back wards, tuning for max  AUDIO out put either by ear or on the scope .There is a very specific method described in the manual, but essentially the same thing.While you are at it, once the IFs are peaked, turn off the modulation, turn on the BFO and zero beat it to the IF. 
IF you still get nothing no matter what of the above you do,, as Gordon said, check the G1 of the 12A6 for a signal.
BTW the AF load if connected terminal 3 of the transformer I believe is 3000 ohms, if connected to terminal 6 is 600 ohms.
Short the 'sensitivity' terminal to ground while testing for max gain.


 

    On Saturday, January 13, 2018 7:50 PM, "kg4kgl at gmail.com" <kg4kgl at gmail.com> wrote:
 

 I did not really tweak any settings other than two move the trimmers to break lose any oxidation. Socket have been sprayed and cleaned gear drive on tuning cap has been lubed. 
I will check for cold tube, either a bad one or an incorrect filament wiring job. All but the mixer tubes are known good ones as I borrowed them from the working bc-454. 
Robert
Sent from my iPhone
On Jan 13, 2018, at 19:41, Tom Lee <tomlee at ee.stanford.edu> wrote:


 
 At the risk of sounding like a broken record, did you check the easy stuff first? Tweaking a bunch of RF/IF stuff without having done so could leave you with a bigger problem than you started with.
 
 Just sayin'.
 -- 
Prof. Thomas H. Lee
Allen Bldg., CIS-205
420 Via Palou Mall
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu
650-725-3383 (public fax; no confidential information, please)  On 1/13/2018 4:37 PM, kg4kgl at gmail.com wrote:
  
 
 I have already restored a BC-454 and aligned it. So that is not a problem. I have sig gen, frequency counter, and scope.  
  When I inject the 2830khz signal, where do I check to see if the IF is picking it up? 
  Tnx, 
  Robert  KG4KGL 
 
 
 On Jan 13, 2018, at 19:26, Robert Eleazer <releazer at earthlink.net> wrote:
 
  
  
If you hear some static but there is no change of any kind in the sound as you tune the receiver then the most likely problem is the LO.     Aside from the obvious possibilities, be sure to check the connections to the coils under the tuning caps.  The fact that they are removable by unplugging them makes them vulnerable to the creation of cold solder joints on the chassis.     The first thing to do would be to try putting a 2830 KHZ signal near the chassis to see if the IF picks it up.  If you don't have a suitable signal generator a cruder approach would be to take the cover off the tuning cap and carefully touch each of the connections to the tuning cap.   Good luck!  
 Wayne WB5WSV        
 
|  | Virus-free. www.avg.com  |

   
 ______________________________________________________________
 ARC5 mailing list
 Home: http://mailman.qth.net/mailman/listinfo/arc5
 Help: http://mailman.qth.net/mmfaq.htm
 Post: mailto:ARC5 at mailman.qth.net
 
 This list hosted by: http://www.qsl.net
 Please help support this email list: http://www.qsl.net/donate.html 
 
  
 ______________________________________________________________
ARC5 mailing list
Home: http://mailman.qth.net/mailman/listinfo/arc5
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:ARC5 at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html 
 
______________________________________________________________
ARC5 mailing list
Home: http://mailman.qth.net/mailman/listinfo/arc5
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:ARC5 at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
______________________________________________________________
ARC5 mailing list
Home: http://mailman.qth.net/mailman/listinfo/arc5
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:ARC5 at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

   
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/arc5/attachments/20180114/865e7d80/attachment.html>