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Old 22nd Aug 2004, 6:36 pm   #1
Radio_Dave
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Default AM stations on LW!

Hi,

I've spent all weekend sorting out various problems on my Pilot Little Maestro . The radio is now working very well on MW but LW is picking up MW stations!

Classic Gold Amber is on 1200 meters LW! I still get all those lovely LW noises as I tune up and down the scale.

Tommorrow I will have a go at aligning it but is this too simple? Does it seem too far off to be down to alignment alone?

David

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Old 22nd Aug 2004, 9:00 pm   #2
Paul Stenning
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Default Re: AM stations on LW!

It sounds like the local oscillator isn't changing frequency when you change over to LW. If this was the case, the MW stations would still be in the correct place on the MW scale, but would be quieter.

The waveband switch probably switches in an extra capacitor to reduce the frequency of the oscillator, but this isn't happening. Alignment won't solve it - and in fact it will probably make things worse.

Check the waveband switching. I don't have the circuit to hand (there are several different "Little Maestro" models), but I doubt this section is very complex if it's a MW/LW set. The relevant contacts are probably not closing, due to damage or dirt or whatever.
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Old 22nd Aug 2004, 10:51 pm   #3
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Default Re: AM stations on LW!

Thanks Paul,

The symptoms you describe are exactly what I have. The radio is the first model and is incredibly simple around the wavechage switch. I should have no problem sorting it out (famous last words!)

Cheers

David
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Old 13th Sep 2004, 1:24 pm   #4
mjizycky
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Default Re: AM stations on LW!

There is one other possibility not mentioned here - that of poor image rejection. I remember some Fidelity transistor radios that used to pick up Radio 1 on long wave (at about 1100m in those days*) because of this. If the station in question is quite powerful locally and is being picked up at

sig. freq. - (2*IF freq.)

on LW then it's poor image rejection caused by wavechange switching faults (aerial tuning not tuning) or really bad alignment! The most likely explanation is Paul's - it's the wavechange switch not doing its job.

* In that case R1 was on 247m, or 1215 KHz. So

1215 - (2*470) = 275 KHz, or approx. 1090 metres.
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Old 13th Sep 2004, 2:16 pm   #5
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Default Re: AM stations on LW!

Hi mjizycky,

Thanks for the reply but Paul's diagnosis was spot on a little switch cleaner and LW came to life.

I am glad you replied though because I clicked you website link and I am finding it very interesting.

Thanks
David

Last edited by Paul Stenning; 6th Mar 2005 at 11:42 am.
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