Forums :: NEW! Web Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Dec Sun 05, 2021 9:21 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 5 posts ] 
Author Message
 Post subject: FM Stuck?
PostPosted: Oct Sun 03, 2021 8:41 pm 
Member
User avatar

Joined: Mar Thu 18, 2021 6:13 pm
Posts: 27
Location: Las Vegas, NV 89002
Hello,

I have an Airline solid state stereo console and the FM is stuck in one band. The dial moves all the way through the bands and I can see the AM fins moving but just getting bad FM reception on one station only throughout the range.....is there a probable cause for this?

Thank you!


Top
 Profile  
 
 Post subject: Re: FM Stuck?
PostPosted: Oct Mon 04, 2021 2:22 pm 
Member

Joined: Aug Sun 23, 2015 6:01 pm
Posts: 1299
Location: NJ 08090
The cable/string for your FM band tuner is broke or loose.


Top
 Profile  
 
 Post subject: Re: FM Stuck?
PostPosted: Oct Mon 04, 2021 3:37 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 10863
Location: Beaver Falls, PA. USA
First, see if there is a separate tuning unit for the FM band. If so, the advice to check the dial cord is spot on; both tuning capacitors must turn together when the tuning knob is operated. If both the AM and FM bands are tuned by the same tuning capacitor assembly (the most common method), then you have a problem with the FM oscillator circuit; a broken connection to the tuning capacitor or coil, or a bad oscillator transistor.

_________________
Tim KA3JRT


Top
 Profile  
 
 Post subject: Re: FM Stuck?
PostPosted: Oct Mon 04, 2021 5:11 pm 
Member
User avatar

Joined: Mar Thu 18, 2021 6:13 pm
Posts: 27
Location: Las Vegas, NV 89002
Tim Tress wrote:
If both the AM and FM bands are tuned by the same tuning capacitor assembly (the most common method), then you have a problem with the FM oscillator circuit; a broken connection to the tuning capacitor or coil, or a bad oscillator transistor.


Thanks Tim, the AM tunes nicely and is connected to the same FM assembly, so I believe it's a bad oscillator.....will check further.



Thanks!


Top
 Profile  
 
 Post subject: Re: FM Stuck?
PostPosted: Oct Wed 06, 2021 12:09 am 
Member
User avatar

Joined: Jul Mon 08, 2013 2:48 pm
Posts: 821
Basil Bond wrote:
Tim Tress wrote:
If both the AM and FM bands are tuned by the same tuning capacitor assembly (the most common method), then you have a problem with the FM oscillator circuit; a broken connection to the tuning capacitor or coil, or a bad oscillator transistor.


Thanks Tim, the AM tunes nicely and is connected to the same FM assembly, so I believe it's a bad oscillator.....will check further.



Thanks!


If the FM tuning cap rotates and is driven correctly by the tuning knob then the local oscillator is very likely dead (or locked to a fixed frequency). You may also try to adjust the L.O trimmer cap (usually mounted on the top of the tuning cap frame, but not allways) to see if it has any effect on the received channel.

Of course since we don't have the type and schematic of your receiver we can only suppose it use a standard V.C tuning in the FM band and not the Varicap diode (DC voltage tuning) system. A Varicap tuning uses a potentiometer coupled to the tuning assembly to generate the tuning voltage. Could you confirm which type it is ?


Top
 Profile  
 
Post New Topic Post Reply  [ 5 posts ] 

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 7 guests



Search for:
Jump to:  




































Privacy Policy :: Powered by phpBB