08-01-2008, 02:07 PM
Hi all,
I have been working on my 650B and have noticed the following characteristics in tuning my radio.
Longwave band.....Antena-Very broad peak.......RF-Sharp peak
Broadcast band.....Antenna- Sharp peak............RF-Very Broad Peak-almost none
Police band............Antenna-Sharp peak.............RF-Sharp peak
Shortwave band....Antenna-Sharp peak.............RF- Sharp peak
I am hoping some of you folks who have a great amount of experience with these 640/650 chassis can weigh in on this. Are the very broad to almost non-existent peaks normal on the broadcast band and the longwave band?
I have noticed that there are two internal capacitors in the rf transformer assembly, caps #16 and #17, associated with the broadcast and police band. I'm not sure of the value of these, but when I measure them with the ohm meter they appear somewhat leaky. Has anyone ever changed these before? What is the value? Could this be the reason for the broad tuning of the rf coil on the broadcast band?
What do you think?
Here is the schematic. http://www.nostalgiaair.org/Resources/824/M0013824.htm
Ed
I have been working on my 650B and have noticed the following characteristics in tuning my radio.
Longwave band.....Antena-Very broad peak.......RF-Sharp peak
Broadcast band.....Antenna- Sharp peak............RF-Very Broad Peak-almost none
Police band............Antenna-Sharp peak.............RF-Sharp peak
Shortwave band....Antenna-Sharp peak.............RF- Sharp peak
I am hoping some of you folks who have a great amount of experience with these 640/650 chassis can weigh in on this. Are the very broad to almost non-existent peaks normal on the broadcast band and the longwave band?
I have noticed that there are two internal capacitors in the rf transformer assembly, caps #16 and #17, associated with the broadcast and police band. I'm not sure of the value of these, but when I measure them with the ohm meter they appear somewhat leaky. Has anyone ever changed these before? What is the value? Could this be the reason for the broad tuning of the rf coil on the broadcast band?
What do you think?
Here is the schematic. http://www.nostalgiaair.org/Resources/824/M0013824.htm
Ed