[Boatanchors] Modified AR-88

[Mark Johnson]

Al, terrific suggestion. I have a CR-91a that I over hauled and aligned a year or so ago and I had the exact same problem. End points align, but in the centre, on the same band, it was out. I was convinced I had an osc trim cap slightly off and thought I'd go after it later. You've provided the answer. Thanks Al. I never would have come up with that but it makes sense now. I guess an old dog like me can learn new tricks!

 

Thanks again Al.

 

Mark V Johnson VE3DJU/VE3DDI
 
> Date: Wed, 20 Jan 2010 21:17:06 -0500
> From: al at ar88.net
> To: boatanchors at mailman.qth.net
> Subject: Re: [Boatanchors] Modified AR-88
> 
> Hi Joe,
> 
> When you get to the upper bands aligning any shortwave superhet, it 
> becomes easy to align it on the wromg side of the local oscillator. The 
> results are the symptom you describe. In an AR-88 the oscillator is 
> always on the "high side."
> 
> Listen for the LO with another receiver. Set the main dial for 10.000, 
> and trim the LO to 10.455 MHz. Then align the RF stages with a 10MHz 
> input. A digital receiver, especially one with memories like a Sony 
> 2010, can make short work of an alignment job using this method..
> 
> Regards,
> Al
> 
> On 1/19/2010 5:17 PM, Joe Connor wrote:
> > OK, some progress and some questions. A larger cap near the audio-gain control stopped the motorboating. The audio is excellent.
> >
> > I'm having some dial-tracking problems on Band 3. I did an RF alignment at 5.0 mhz and 10.0 mhz and both are spot on. The midpoints, however, are way off. For example, I get CHU (7.850 mhz) at about 8.2 mhz. Any ideas?
> >
> > Joe Connor
> >
> >
> >
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> 
> -- 
> Al Klase - N3FRQ Jersey City, NJ http://www.skywaves.ar88.net/
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