Vintage Receiver AM Antenna Replacement

[prubino]

Would anyone be able to recommend a replacement AM antenna that can be used with a Nikko NR-1415 receiver. The antenna is snapped completely off the receiver and needs to be replaced. i have been unable to find a direct replacement from another Nikko NR-1415, and was wondering if another AM antenna would work with this receiver. The antenna has 5 wires mounted to the back of the receiver

I am attaching the AM antenna description and the wiring diagram for the NR-1415 from the service manual if this helps determine one that would work.

Any assistance would be appreciated

 

[Tom B]

many time you can find a sub doing searches on places like Ebay. Find ones with a similar mount, or a mount that you could use. Then make sure you can see the wiring on the ones for sale. make sure it is a 5 wire, and try and find one with the same color wires. Then match this antenna's schematic depiction compared to yours. If it looks the same, try it. Same make like Nikko would be closer as a match, but others may be out there as well.

 

[prubino]

many time you can find a sub doing searches on places like Ebay. Find ones with a similar mount, or a mount that you could use. Then make sure you can see the wiring on the ones for sale. make sure it is a 5 wire, and try and find one with the same color wires. Then match this antenna's schematic depiction compared to yours. If it looks the same, try it. Same make like Nikko would be closer as a match, but others may be out there as well.

Tom B . . . Thanks for your feedback. Much appreciated.

 

[sKiZo]

Your receiver also has attachment points for an external long wire. Better performance, and a lot easier than trying to find a replacement?

Around 25 feet of 18 gauge stranded wire should do the job. Couple nails in the attic, tie one end of the wire to one nail, and just wrap the other end around another nail, then drop the wire down to your receiver.

Or you can solder a couple brass slinkies together like I did. <G>

Works great - it's just strung on a couple lengths of weed wacker cord tied off to a couple other masts, and gives me an effective length of around 160 feet in a 20 foot span. I can do late night scanning with my old tuber and get hits every 10kc's on that, dragging the whole world in if conditions are right ...

* DO make sure the receiver is grounded if you go with an external type antenna.

PS ... there's also any one of a hundred loop type antennas you can purchase that will hook up to your AM connection. Only drawback there is most need to be tuned along with the receiver for max gain, and that can be a bit of a pain if you're scanning the band.

 

[I LIKE MUSIC]

Your receiver also has attachment points for an external long wire. Better performance, and a lot easier than trying to find a replacement?

sKiZo, it appears from the schematic that the external AM antenna connection signal is coupled to the radio through the built in AM antenna. Without the built in antenna, there will not be any connection to R201, per the schematic. This is the AM signal input.



One could follow the wires to find which one goes to R201 and connect it to the external antenna connection. There performance might suffer a little as there would not be any pre-tunning of the signal. This can and does make a difference, especially with weaker signals.

 

[prubino]

Your receiver also has attachment points for an external long wire. Better performance, and a lot easier than trying to find a replacement?

Around 25 feet of 18 gauge stranded wire should do the job. Couple nails in the attic, tie one end of the wire to one nail, and just wrap the other end around another nail, then drop the wire down to your receiver.

Or you can solder a couple brass slinkies together like I did. <G>

Works great - it's just strung on a couple lengths of weed wacker cord tied off to a couple other masts, and gives me an effective length of around 160 feet in a 20 foot span. I can do late night scanning with my old tuber and get hits every 10kc's on that, dragging the whole world in if conditions are right ...

* DO make sure the receiver is grounded if you go with an external type antenna.

PS ... there's also any one of a hundred loop type antennas you can purchase that will hook up to your AM connection. Only drawback there is most need to be tuned along with the receiver for max gain, and that can be a bit of a pain if you're scanning the band.

Thanks for the info sKiZo.

 

[I LIKE MUSIC]

Prubino, you need to read my post.

If the schematic that you posted is correct, there is nothing connected to the external antenna connection without the built in antenna. Connecting a long wire antenna to the external antenna connection is connecting to a terminal with nothing connected to it.

There may be a small amount of signal coupled via the loose wires, but it will not be a direct connection, which is what you need.

Again, look at the schematic, if correct, it shows that without the built in antenna there is no connection to R201, which is the input to the AM section.

 

[sKiZo]

One way to find out ... get a roll of hobby wire from the auto store, hook it up, and stretch it out. If you get signal, you're golden.

Wire's handy to have around anyway if it don't work.

 

[I LIKE MUSIC]

There may be some signal, but that does not necessarily mean gold. Since those wires are now unterminated, there may be some signal coupling between them, but still not a direct connection. I guess in this case an error in a schematic could be a good thing.

To be clear, there is nothing wrong with giving it a try, if on understands all of the gotchas.

 

[dr*audio]

If the wires aren't broken I advise against replacing the antenna unless you find one from the exact model. You will never figure out where to connect the wires. Use some ingenuity and fashion a new mount. It needs to be plastic where it holds the antenna. Something like this.

 

[prubino]

Prubino, you need to read my post.

If the schematic that you posted is correct, there is nothing connected to the external antenna connection without the built in antenna. Connecting a long wire antenna to the external antenna connection is connecting to a terminal with nothing connected to it.

There may be a small amount of signal coupled via the loose wires, but it will not be a direct connection, which is what you need.

Again, look at the schematic, if correct, it shows that without the built in antenna there is no connection to R201, which is the input to the AM section.

I Like Music . . . the wiring diagram is right from the Nikko service manual so it is accurate. Thanks for your feedback. I think the best option will to search for a replacement AM antenna that has the matching 5 wires and try this as a replacement. So far, my search has found a lot of 4-wire versions but I am not sure if these would work. I will keep searching.

 

[prubino]

If the wires aren't broken I advise against replacing the antenna unless you find one from the exact model. You will never figure out where to connect the wires. Use some ingenuity and fashion a new mount. It needs to be plastic where it holds the antenna. Something like this.

Unfortunately this is not an option as the antenna is snapped completely off.

 

[DRecovery]

There may be some signal, but that does not necessarily mean gold. Since those wires are now unterminated, there may be some signal coupling between them, but still not a direct connection. I guess in this case an error in a schematic could be a good thing.

To be clear, there is nothing wrong with giving it a try, if on understands all of the gotchas.

The built-in AM antenna is a part of the circuit and is usually a tuned coil from what I have seen on Pioneer, Yamaha, et al., receivers. There is an adjustable ferrite slug inside that is set when doing the AM alignment.

It looks like T2 is the built-in antenna in the schematic.

 

[prubino]

I found an AM antenna online from a Pioneer QX-8000A. It has 5 wires similar to the one on my Nikko NR-1415. I have provided below the Nikko and Pioneer AM Antenna wiring diagrams for comparison. Would anyone be able to confirm if this Pioneer AM antenna would work with my Nikko receiver?

Nikko NR-1415 AM Antenna Wiring Diagram

Pioneer QX-8000A AM Antenna Wiring Diagram

 

[DRecovery]

I can't see the Pioneer image but if the wiring looks similar it's definitely worth a shot. I doubt you will do any harm, but to see the benefit you will likely need an alignment.

 

[I LIKE MUSIC]

Without knowing the inductance of the replacement antenna, because as already posted the antenna is part of a tuned circuit and the replacement antenna that you reference may or may not match. If the replacement antenna that you referenced in close, just to make it work, only the first stage of the RF section of the AM section would need to be adjusted. The antenna its self may or may not be adjustable. If it is, it is just a matter of adjusting it and the trimmer capacitor for the first AM RF stage for maximum sensitivity. This can be done using a weak AM station.

The color coding of the wires may not be the same.

 

[Pio1980]

You will likely have to carefully tweak the inductance of the replacement antenna for best sensitivity at the low end of the dial ca 550 kc, usually a flat screw thingus in the end of the antenna rod, which is of fragile ferrite ceramic. Then tweak ONLY the antenna RF tuner trimming padder for best sensitivity ca 1500-1600 kc. Repeat each until no improvement occurs.
This procedure assures best potential AM reception.

 

[I LIKE MUSIC]

^ Exactly.

 

[prubino]

Without knowing the inductance of the replacement antenna, because as already posted the antenna is part of a tuned circuit and the replacement antenna that you reference may or may not match. If the replacement antenna that you referenced in close, just to make it work, only the first stage of the RF section of the AM section would need to be adjusted. The antenna its self may or may not be adjustable. If it is, it is just a matter of adjusting it and the trimmer capacitor for the first AM RF stage for maximum sensitivity. This can be done using a weak AM station.

The color coding of the wires may not be the same.

Thanks for the information and guidance . . . I will post back once I give it a try and see how it goes.

 

[I LIKE MUSIC]

Good luck with the project.