heathkit sb301 receiver - UK Vintage Radio Repair and Restoration Discussion Forum

carlos10 · 25th Sep 2007, 6:42 pm

hello all,

have a problem with am receiving ,
switching to am mode with mode switch results in no audio,
s meter is still deflecting in this mode,
very very low audio signal is to be heard, almost nothing,
normally in this mode the audio most be very noisy like all other modes,
the receiver is all tube design
in all other modes radio works ok, audio also ok
any tips were to start searching for locating the fault are welcome,
thank you carlos

radiomonkey · 28th Sep 2007, 5:35 pm

Does the Rx have a seperate AM detector and also a Product detector for CW/SSB ? Often the AM detector is adiode and when this goes it could act more like a resistor

I may be a long way off here, but it's an idea

Radiomonkey

Station X · 28th Sep 2007, 8:59 pm

radiomonkey. The circuit can be downloaded here for free:-

http://www.vintage-radio.info/heathkit/index.htm

carlos10 · 29th Sep 2007, 12:18 pm

Quote:

Originally Posted by radiomonkey

Does the Rx have a seperate AM detector and also a Product detector for CW/SSB ? Often the AM detector is adiode and when this goes it could act more like a resistor

I may be a long way off here, but it's an idea

Radiomonkey

hello,
thanks reply,
in am mode the bfo is turned off and the produkt detektor is disconnected,
from the audio amplifier,
if output signal is coupled trough a capacitor to the am detektor diode,
this detektor diode is a resistor diode combination,
a 470k resistor is soldered parallel to the diode, 1n91 crystal diode original,

would be interesting to now were to measure ,
i have a scoop and signal generator ,
however it is my first try to repair ,
regards carlos

carlos10 · 29th Sep 2007, 12:55 pm

Quote:

Originally Posted by carlos10

hello,
thanks reply,
in am mode the bfo is turned off and the produkt detektor is disconnected,
from the audio amplifier,
if output signal is coupled trough a capacitor to the am detektor diode,
this detektor diode is a resistor diode combination,
a 470k resistor is soldered parallel to the diode, 1n91 crystal diode original,

would be interesting to now were to measure ,
i have a scoop and signal generator ,
however it is my first try to repair ,
regards carlos

quik update,
problem solved,
resistor over the diode was wrong and also bad soldering,
regards carlos

radiomonkey · 1st Oct 2007, 9:14 pm

Carlos

Pleased you got it sorted and hope I was of some small help !

All the best

Radiomonkey

25th Sep 2007, 6:42 pm	#1
carlos10 Pentode Join Date: Apr 2007 Location: Sint-eloois-winkel 8880, Belgium. Posts: 168	heathkit sb301 receiver hello all, have a problem with am receiving , switching to am mode with mode switch results in no audio, s meter is still deflecting in this mode, very very low audio signal is to be heard, almost nothing, normally in this mode the audio most be very noisy like all other modes, the receiver is all tube design in all other modes radio works ok, audio also ok any tips were to start searching for locating the fault are welcome, thank you carlos

28th Sep 2007, 5:35 pm	#2
radiomonkey Retired Dormant Member Join Date: Sep 2007 Location: Ongar Posts: 4	Re: heathkit sb301 receiver Does the Rx have a seperate AM detector and also a Product detector for CW/SSB ? Often the AM detector is adiode and when this goes it could act more like a resistor I may be a long way off here, but it's an idea Radiomonkey

28th Sep 2007, 8:59 pm	#3
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: heathkit sb301 receiver radiomonkey. The circuit can be downloaded here for free:- http://www.vintage-radio.info/heathkit/index.htm __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

1st Oct 2007, 9:14 pm	#6
radiomonkey Retired Dormant Member Join Date: Sep 2007 Location: Ongar Posts: 4	Re: heathkit sb301 receiver Carlos Pleased you got it sorted and hope I was of some small help ! All the best Radiomonkey