Just picked up a 1930s Battery operated Coronado

[fixmeplease]

i'd wait for the caps and replace them before worrying about anything else.

[Electronic M]

It should be possible to align the IF cans 10KHz off designed frequency. Nothing to loose trying it. If they don't peak in range of adjustments you could try tacking pF caps across windings to see if you can get more range.

[vortalexfan]

Originally Posted by Electronic M

It should be possible to align the IF cans 10KHz off designed frequency. Nothing to loose trying it. If they don't peak in range of adjustments you could try tacking pF caps across windings to see if you can get more range.

Well what's interesting is that the 1st IF can's IF Frequency is 10 KC lower than the original IF Frequency, and the 2nd IF can's IF Frequency is 10 KC higher than the original IF Frequency of 465 kHz, which I'm not sure what the point of that would of been but its kind of bizarre.

And I guess I can see what happens as far as trying to align the IF cans to the original 465 kHz IF Frequency.

[old_tv_nut]

Nice!

[Titan1a]

Bravo! Very, very nice.

[vortalexfan]

Originally Posted by Titan1a

Bravo! Very, very nice.

Thanks! This was my first repair where I actually had to replace more than just the caps or resistors in one of these radios, and it was my first farm radio that I've ever worked on.

And to be honest, with just my 2 1.2v NiMH rechargeable D batteries installed in a regular old Radio Shack Battery Clip wired up to a 1N4007 Diode for voltage drop the radio actually played for about 3 1/2 hours with plenty of juice to spare and the batteries weren't even fully charged!

[old_coot88]

Like a Boss! Coool, dude!

[vortalexfan]

Originally Posted by old_coot88

Like a Boss! Coool, dude!

Thanks! I think this will be my new Go To radio for Night Time DX'ing since it's a battery set and I could drag it out into a park out in the middle of nowhere and string up an antenna and just cruise the dial and see how many distant stations I can get in.

[old_coot88]

Originally Posted by vortalexfan

...since it's a battery set and I could drag it out into a park out in the middle of nowhere and string up an antenna and just cruise the dial and see how many distant stations I can get in.

After a radio's been fixed and working good, often you can squeeze just a bit more gain out of the IFs; tune to a weak station that's almost "down in the grass" and then re-tweak each of the IF trimmers for absolute max gain. Often just the tiniest fraction of a turn makes a difference.

BTW, does the tuning spread match the dial markings pretty well?

[fixmeplease]

Glad you have it fixed! Enjoy

[Kevin Kuehn]

Hey you did good. Seems to be working really well, and it's quite sensitive. That will be very interesting once you get outdoors away from all the modern rf noise sources. If you have a scope with a DC coupling you can monitor the AVC voltage line and watch the trace move up and down as you change the tuning.

[vortalexfan]

Originally Posted by Kevin Kuehn

Hey you did good. Seems to be working really well, and it's quite sensitive. That will be very interesting once you get outdoors away from all the modern rf noise sources. If you have a scope with a DC coupling you can monitor the AVC voltage line and watch the trace move up and down as you change the tuning.

Yes I do have an oscilloscope, and I think it does have DC Coupling but I'm not sure, the 'scope I have is a Tektronix Model 453 that is a Hybrid (part solid state part Nuvistor Tube powered).

How do I know if the 'scope I have has DC Coupling?

[old_tv_nut]

Originally Posted by vortalexfan

Yes I do have an oscilloscope, and I think it does have DC Coupling but I'm not sure, the 'scope I have is a Tektronix Model 453 that is a Hybrid (part solid state part Nuvistor Tube powered).

How do I know if the 'scope I have has DC Coupling?

You don't need a scope for this - a DC voltmeter will work.

[Kevin Kuehn]

Tis true but it's more fun watching the scope trace in a dimly lite room. Plus it's a great way to get comfortable working all those intimidating controls. Most modern scopes have a AC-DC coupling switch near each channel input.

[old_tv_nut]

A frequency counter is much more precise at measuring frequency than a scope, so the counter could be used to calibrate the frequency of the signal generator, and then the signal generator could be used to calibrate the scope sweep time. Doing the opposite order would result in much larger errors.