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R-4B and 50khz T11

 

Good morning friends of the Drake group. I have been given a faulty rx R-4B as a gift. I overhauled the power supply part which was found to be faulty. The radio now turns on receives its internal marker, the preselector works . But the signal is very distorted. The s-meter goes full scale left to negative. Continuing the checks I found the T11 transformer broken and with the internal coils charred. I think it is impossible to find a T11 as a replacement or at least to know the characteristics in order to rebuild it. Another possibility would be to redesign with modern components this part of the circuit also inserting a new product detector. What do you think ? am I crazy?
Best regards 73 de Matteo ik2gsr
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Matteo, you are not crazy but you must be determined. The distortion tells me something is amiss with the AGC system -- incorrect AGC voltage or bad interstage coupling caps putting B+ on the grids.
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As for T11, the easiest way is to watch eBay for the part to show up. You can certainly build a new coil, or perhaps adapt a new part that you find with Google, but that will be more work.
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Good luck, and keep us posted.
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Dave
 


I have one but am not sure about what would be involved with shipping. ?Are there still issues with sending parcels to Italy? ?


Steve Wedge, W1ES

Time flies like an arrow. Fruit flies like a banana.




On Fri, Jan 31, 2025 at 4:44 PM, Dave W7GZ via groups.io <w7gz@...> wrote:
Matteo, you are not crazy but you must be determined. The distortion tells me something is amiss with the AGC system -- incorrect AGC voltage or bad interstage coupling caps putting B+ on the grids.
?
As for T11, the easiest way is to watch eBay for the part to show up. You can certainly build a new coil, or perhaps adapt a new part that you find with Google, but that will be more work.
?
Good luck, and keep us posted.
?
Dave

 

Thanks Steve, with your help I may be able to make this Drake R-4B sing again. Steve there are no problems with package delivery in Italy. Poste Italiane are working well. I regularly receive shipments from China and all European countries. If you can send me the T11 in a padded envelope and let me know the total expense of the T11 + shipping I will arrange to send you the money via Paypal or bank transfer to your account. Let me know if the operation is possible. Best regards Matteo ik2gsr
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