duplicating stations top of band;bottom of band - Printable Version
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+--- Thread: duplicating stations top of band;bottom of band (/showthread.php?tid=15143)
duplicating stations top of band;bottom of band - tomt - 08-04-2016
Hi to all I am fairly new to the phorum;but however I will try to state clearly. my problems.I am restoring a philco model 41-260 I have replaced all capacitors and the radio is working on the am band and the short wave band. I had to replace the band switch wow! ok it receives a station at 1600kc and the same station at around 700kc I have performed an alignment which did help; but can any one tell how to cure the harmonic I think that is the term Thanks everyone Tom ( ps I been out of electronics since the seventies sorry for any mistakes.
RE: duplicating stations top of band;bottom of band - klondike98 - 08-04-2016
Welcome to the Phorum!
RE: duplicating stations top of band;bottom of band - Radioroslyn - 08-04-2016
Hi Tom,
A few things come to mind. Is the station at 1600kc really strong?? Close by and running some power? May just be a case of front end overload.
Double check the wiring of the loop ant and the band switch. The front end selectivity isn't going to be super duper as there is only one tuned circuit at the rf input. Any thing that is miss wired can detune it.
GL
RE: duplicating stations top of band;bottom of band - tomt - 08-04-2016
Thanks stations are strong across the band since there are so few am stations any more I almost have to wait until night comes; the radio seems to track; but does duplicate upper stations at the lower end of band.example gets 1500kc at close to 600kc and 1600kc around 800kc I will recheck wiring again
RE: duplicating stations top of band;bottom of band - Radioroslyn - 08-04-2016
Something else comes to mind, check the LO frequency to be sure it's on the high side of the signal and not the low side.
RE: duplicating stations top of band;bottom of band - tomt - 08-05-2016
(08-04-2016, 10:48 PM)Radioroslyn Wrote: Something else comes to mind, check the LO frequency to be sure it's on the high side of the signal and not the low side.
being away from any repairs for about 35 yeas makes it kind of hard! do you mean set to high side of 455kc if I missed a wire or got one wrong in wrong place on the band switch could this cause my problem. man I used to think I could work on radios some of these old ones will challenge me Thank for your help. ps I was looking at you gallery and seen your 84b; I have one like it I am working on I got into vintage about a year ago having fun!!
RE: duplicating stations top of band;bottom of band - Radioroslyn - 08-05-2016
(08-05-2016, 06:20 PM)tomt Wrote:(08-04-2016, 10:48 PM)Radioroslyn Wrote: Something else comes to mind, check the LO frequency to be sure it's on the high side of the signal and not the low side.
being away from any repairs for about 35 yeas makes it kind of hard! do you mean set to high side of 455kc if I missed a wire or got one wrong in wrong place on the band switch could this cause my problem. man I used to think I could work on radios some of these old ones will challenge me Thank for your help. ps I was looking at you gallery and seen your 84b; I have one like it I am working on I got into vintage about a year ago having fun!!
What mean is the lo frequency must be 455kc above the incoming rf signal. For instance if you dial is set at 800kc the lo fq should at 1255kc. LO fq= dial fq + IF fq (your IF is 455kc) LO fq of 1255kc is 455kc above the 800kc that the dial is set to. You can listen for it in another reciever with the ant lead near the mixer tube.
Connecting a wire in the wrong place probably won't shift the oscilltor to the other side of the IF but it could cause some other issues that might cause your image problem.
I've been at it since the '60s when I was a kid and lately I had several real butt kickers! That 660L and thev42-854 where no picnic. It takes a lot of perseverance for sure!
On the 84 you need to replace all of the ecaps/foil paper and all of the resistors except the ww in the bias circuit. Rewiind the primary on the ant and osc coils and it will work swell!
RE: duplicating stations top of band;bottom of band - tomt - 08-06-2016
(08-05-2016, 08:31 PM)Radioroslyn Wrote:(08-05-2016, 06:20 PM)tomt Wrote:(08-04-2016, 10:48 PM)Radioroslyn Wrote: Something else comes to mind, check the LO frequency to be sure it's on the high side of the signal and not the low side.
being away from any repairs for about 35 yeas makes it kind of hard! do you mean set to high side of 455kc if I missed a wire or got one wrong in wrong place on the band switch could this cause my problem. man I used to think I could work on radios some of these old ones will challenge me Thank for your help. ps I was looking at you gallery and seen your 84b; I have one like it I am working on I got into vintage about a year ago having fun!!
What mean is the lo frequency must be 455kc above the incoming rf signal. For instance if you dial is set at 800kc the lo fq should at 1255kc. LO fq= dial fq + IF fq (your IF is 455kc) LO fq of 1255kc is 455kc above the 800kc that the dial is set to. You can listen for it in another reciever with the ant lead near the mixer tube.
Connecting a wire in the wrong place probably won't shift the oscilltor to the other side of the IF but it could cause some other issues that might cause your image problem.
I've been at it since the '60s when I was a kid and lately I had several real butt kickers! That 660L and thev42-854 where no picnic. It takes a lot of perseverance for sure!
On the 84 you need to replace all of the ecaps/foil paper and all of the resistors except the ww in the bias circuit. Rewiind the primary on the ant and osc coils and it will work swell!
ok thanks I will keep on working on it; it is great therapy for old age
