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Collins 51J2




 
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Author Topic: Collins 51J2  (Read 1102 times)
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n1ps
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« on: August 02, 2021, 09:31:05 AM »

I figure some on here are familiar with this receiver.  It has an odd issue.  Above the BC band, it receivers 1MHZ higher than what is dialed up.  For example, on band 2, setting dial to 1.9 MHz, it actually receivers on 2.9.  On band 4, with dial set to 3.9, it receivers on 4.9, etc on up.  Band 3 is dead and may be another issue.  The BC band is correct.  At the moment I would like to figure out the wrong band issue first.  Possible a bandswitch issue being set wrong (like someone removed it and set it back one position off)?

TNX
Peter



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WBear2GCR
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Brrrr- it's cold in the shack! Fire up the BIG RIG


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« Reply #1 on: August 02, 2021, 01:55:09 PM »

First carefully check to see that the xtals for the xtal osc are installed in the proper sockets, sounds like they are NOT?

Then you can double check with a freq counter and see that the correct freq is being picked for each band.
Or a scope and do the conversion from time to freq...

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_-_- bear WB2GCR                   http://www.bearlabs.com
n1ps
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« Reply #2 on: August 02, 2021, 03:24:10 PM »

update:  Turns out the bandswitch drum is out of alignment by abt 1/2 of a position.  The actual problem is the even bands are dead at least on the lower bands.   It may be the crystal switch is not synched correctly with the BSW.  More work to be done on this.  I am pretty unfamiliar with this set...but getting more familiar with it as I go through it! 
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n1ps
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« Reply #3 on: August 02, 2021, 04:47:35 PM »

All good.  Everything was badly out of alignment. 
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WBear2GCR
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« Reply #4 on: August 02, 2021, 05:26:42 PM »

way to go!

post pic?
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_-_- bear WB2GCR                   http://www.bearlabs.com
n1ps
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« Reply #5 on: August 03, 2021, 04:26:19 PM »

Will do when complete.  Not out of the woods quite yet.  The even bands are abt 6-8db worse than the odd for senselesstivity.  There are a couple adjustments for this associated with the IF switch shaft, but that did not fix the imbalance.  It doesnt help that the print I have is poor and I gather there are several errors on it from reading around the web.   
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n1ps
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« Reply #6 on: August 13, 2021, 08:44:55 PM »

Finished up the 51J a few days ago.  The pic shows the repair for a couple loose IF coils.  One had a broken wire for the even bands.  Started it several months ago...works well now on all bands.  Impressive engineering.  It belongs to my son in law Jay.  He will enjoy this one.


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