Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12) x

Thread Closed
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Fairbanks Morse Model 8a Problem
#2

Thanks to all who read my first post. I can guess that all of you figured out I was confused..and I was so here is the latest and acccuarte account of the problem I am searching for.

I finished replacing all resistors, caps, and filters. I also put in new tubes just to be sure.  My problem is lower than average volume with a little distortion above 65%(almost like not enough wattage?).....I did a voltage check of the tubes and here is what I now have,

5y3...300v at pins 2&8...-54v at pins 4&6..spec is 245v and -95...high B+ and low bias..correct?
6l7....3oov at pin 3....150v at pin 4 spec is 240 and 105.

Similar pattern throughout th rest of the tubes.  B+ voltage at the filter is 300v bias -54.

The field coil resistance is 795ohms cold, 839 after 2 minutes...spec is 1000 ohms hot.  I did not want to play for too long with the high B+ v.

I do not have any specs on the transformer, only the schematic from Nostalgia Air.

Could I have a transformer issue or is there something I am missing to cause the low bias?  

There is supposed to be an antenna lead and a ground wire, only one is left and I'm thinking since it goes to the a band selector 
lug that in turn goes to ground...means itis the ground and not the antenna lead right?  If so where would be a good place to attach a lead for antenna? 

   Bob


Messages In This Thread
Fairbanks Morse Model 8a Problem - by bm071 - 01-15-2016, 10:23 AM
RE: Fairbanks Morse Model 8a Problem - by bm071 - 01-18-2016, 10:24 AM
RE: Fairbanks Morse Model 8a Problem - by bm071 - 01-18-2016, 10:40 AM
RE: Fairbanks Morse Model 8a Problem - by bm071 - 01-18-2016, 08:37 PM
RE: Fairbanks Morse Model 8a Problem - by bm071 - 01-20-2016, 10:19 AM
RE: Fairbanks Morse Model 8a Problem - by bm071 - 01-20-2016, 06:55 PM
RE: Fairbanks Morse Model 8a Problem - by bm071 - 01-20-2016, 06:59 PM
Fairbanks Morse Problem Update/ Guidence? - by bm071 - 01-16-2016, 12:51 PM



Users browsing this thread: 2 Guest(s)
[-]
Recent Posts
Philco model 60
This is my thread on 60 from 2016. I had to rewind the osc coil, and I actually counted the turns and then rewound i...morzh — 03:34 PM
Philco model 60
Yes, Mark belongs to the same Michigan Antique Radio Club that I do. I suspect that the oscillator coil is in need of a ...Radios1340 — 03:10 PM
A Marconi model 86
Yeah. I am dreading the thought of what to do with all my consoles when I will no longer be able to move them around. I...morzh — 02:51 PM
1947 Silvertone 7086 Wire Recorder/Phono/Radio on YouTube
Cool gadget, Buzz. I took me a couple of second to undestand that that oscillating thing makes the wire to spool correc...morzh — 02:50 PM
A Marconi model 86
My back hurts already, you could build a house with all the wood. PaulPaul Philco322 — 02:49 PM
1947 Silvertone 7086 Wire Recorder/Phono/Radio on YouTube
Part 4 of this series now uploaded link below to anyone interested Buzz — 02:39 PM
Philco model 60
Welcome to the Phorum, Radios1340!  The oscillator coil on the 60 is a common culprit.  I just bought a 60B (June 1934) ...GarySP — 02:33 PM
Philco model 60
Yes, standard alignment procedure. I can get the minuscule tone to vary when adjusting the trimmers. But you almost have...Radios1340 — 01:40 PM
A Marconi model 86
An imposing-looking radio, for sure.morzh — 12:43 PM
Philco model 60
Model 60 struck again :lol: Welcome to the Phorum! Above is the article on Model 60. Could be of some use. Now...morzh — 12:38 PM

[-]
Who's Online
There are currently 10781 online users. [Complete List]
» 3 Member(s) | 10778 Guest(s)
AvatarAvatarAvatar

>