Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Aug Tue 04, 2020 3:53 pm


All times are UTC [ DST ]





Post New Topic Post Reply  [ 32 posts ]  Go to page Previous  1, 2
Author Message
 Post subject: Re: What Wire for AM Loop Antenna?
PostPosted: May Tue 26, 2020 6:44 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 35402
Location: SoCal, 91387
flyer92 wrote:
So....after borrowing a friend's Tecsun AN200 loop antenna, I tried to inductively couple it with my old tube radio's wire antenna. Nothing happened

I don't understand what the problem is. You posted this earlier;

flyer92 wrote:
Thanks, fifties. So...if I already have a wire antenna coming out of the back of my radio, can I just attach it to the external AM loop?

flyer92 wrote:
OK, great...that's pretty much what I was thinking. There's actually an alligator clip at the end of my radio's long wire antenna (I got it that way), so was also thinking about clipping it somewhere on the loop as well. However, I just don't know where it would be most appropriate to do that. I'm sure wrapping it a few times as you mentioned is probably just as good.


All you have to do is connect the lead from the Tecsun to the lead coming from the antenna terminal of the radio. Don't worry about inductive coupling if you have a lead from the tunable loop to connect to the set's antenna terminal.

_________________
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins/////////////////////////


Top
 Profile  
 
 Post subject: Re: What Wire for AM Loop Antenna?
PostPosted: May Tue 26, 2020 7:26 pm 
Member
User avatar

Joined: May Fri 01, 2020 5:00 pm
Posts: 28
Location: Southern California, USA
Chas...I was concerned about that as well. Unfortunately, my radio was sold as a 1939 Wilcox-Gay model 6AC5, but the factory-original chassis is much different than the actual schematic, and I cannot find the right one. The radio has been inspected by two different technicians, who corroborated this inconsistency, and were also unable to find a schematic, which makes it difficult to determine how best to connect external antennae/devices. That said, there doesn't seem to be much difference between the 80-foot long wire I often attach to the existing wire antenna coming out of my radio vs. an adjustable AM loop antenna. Main differences are the shape/construction of a loop antenna and its inclusion of an adjustable air capacitor, so just curious how the loop would potentially damage anything.

Fifties...there was no lead coming out of the Tecsun, just the socket where the 1.8mm plug for a lead would go, and I didn't have the right wire or plug to make one at the moment. I did actually touch the radio's long wire antenna to the socket, but nothing happened. Of course, a lead coming from the Tecsun's socket would also include a ground wire, so perhaps that was the problem?

Sorry for my seemingly inane questions. Again...I have very minimal experience with electronics, and am just trying to learn enough so I can improve performance on these nice old radios (without damaging them, of course). Please forgive my lack of expertise, and I appreciate your time and attention. Many thanks.


Top
 Profile  
 
 Post subject: Re: What Wire for AM Loop Antenna?
PostPosted: May Tue 26, 2020 7:51 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 5831
Location: Beautiful Downtown Burbank CA
The AN-200
Built-in output socket to output the signal directly for using with the radio which has the external medium wave antenna input socket (the connection cable coming in the package has the 3.5mm stereo standard plug only).


Attachments:
tunable_mw_loop_antenne_an_200_1838401.png
tunable_mw_loop_antenne_an_200_1838401.png [ 4.07 KiB | Viewed 452 times ]
Top
 Profile  
 
 Post subject: Re: What Wire for AM Loop Antenna?
PostPosted: May Tue 26, 2020 8:31 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 14446
Location: S. Dartmouth MA 02748-1225 USA
Attachment:
Screenshot_2020-05-26 Wilcox-Gay Corp 6AC5 - M0024554.png
Screenshot_2020-05-26 Wilcox-Gay Corp 6AC5 - M0024554.png [ 129.52 KiB | Viewed 451 times ]


Hmm, some information is, occasionally, better than no information...

Seems in the 6AC5 there are or should be three leads to work with for an antenna/loop connection.

That assumes the input for those connections complies with the 6AC5 as seen above...

Chas

_________________
List' & I will Enchant Thine Ear


Top
 Profile  
 
 Post subject: Re: What Wire for AM Loop Antenna?
PostPosted: May Tue 26, 2020 9:53 pm 
Member
User avatar

Joined: May Fri 01, 2020 5:00 pm
Posts: 28
Location: Southern California, USA
Thanks, Mike...I meant 3.5mm, not 1.8mm.

Chas...many thanks. I have the same schematic, but the chassis in my radio is much different. At least it was a factory job, so there's still a chance I might eventually find the right one.


Top
 Profile  
 
 Post subject: Re: What Wire for AM Loop Antenna?
PostPosted: May Tue 26, 2020 11:11 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2325
Location: Saskatoon
Chas wrote:
Seems in the 6AC5 there are or should be three leads to work with for an antenna/loop connection.

Two of those leads are effectively connected to ground.

There is a situation in some receivers that have a built in rotatable loop where 3 leads connect between the chassis and the loop.
1. ground
2. pickup loop - actual RF signal input to receiver
3. main loop winding - connected to receiver's variable cap for tuning the loop


Top
 Profile  
 
 Post subject: Re: What Wire for AM Loop Antenna?
PostPosted: May Tue 26, 2020 11:50 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 14446
Location: S. Dartmouth MA 02748-1225 USA
BobWeaver wrote:
Chas wrote:
Seems in the 6AC5 there are or should be three leads to work with for an antenna/loop connection.

Two of those leads are effectively connected to ground.

There is a situation in some receivers that have a built in rotatable loop where 3 leads connect between the chassis and the loop.
1. ground
2. pickup loop - actual RF signal input to receiver
3. main loop winding - connected to receiver's variable cap for tuning the loop
The O.P. has confirmed that is not the schematic... Yes, as you see it, at least two wires connect to "ground" via the line cord and the chassis.

flyer92Take the time to carefully remove the chassis from the radio and take images of the front, the rear and looking down. Note the tube line up and post the data here. With the many users it may be possible to identify the chassis and correctly resolve how to make external antenna/loop connections.
The pictures will also indicate if there is an onboard loop or an antenna coil, since it has two bands I suspect that there is an antenna coil. That would confirm why inductive coupling did not succeed...

YMMV

Chas

_________________
List' & I will Enchant Thine Ear


Last edited by Chas on May Thu 28, 2020 12:20 am, edited 1 time in total.

Top
 Profile  
 
 Post subject: Re: What Wire for AM Loop Antenna?
PostPosted: May Wed 27, 2020 12:47 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 35402
Location: SoCal, 91387
flyer92 wrote:

Fifties...there was no lead coming out of the Tecsun, just the socket where the 1.8mm plug for a lead would go, and I didn't have the right wire or plug to make one at the moment.

Sorry old boy, and you are correct; the Tecsun simply has a jack with which to plug in a 3.5 mm stereo plug (I went and took a look at mine this time, to verify).
I am quite sure that when you find a correct stereo plug and wire it to the set, you will see good reception.


Attachments:
Tecsun AN 200 stereo plug.jpg
Tecsun AN 200 stereo plug.jpg [ 687.32 KiB | Viewed 437 times ]

_________________
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins/////////////////////////
Top
 Profile  
 
 Post subject: Re: What Wire for AM Loop Antenna?
PostPosted: May Wed 27, 2020 9:52 pm 
Member
User avatar

Joined: May Fri 01, 2020 5:00 pm
Posts: 28
Location: Southern California, USA
Chas...before I pull the chassis, I just wanted to verify whether this is a coil antenna inside my radio. If so, then it explains the lack of inductive coupling as you mentioned. Also...for what it's worth, my radio only came with an antenna lead...no other wires or terminals, including those for a ground. So, to ensure the radio was properly grounded, I ran a wire from one of the chassis mounting screws to a switchplate screw on a nearby electrical socket.


Attachments:
IMG_1657.JPG
IMG_1657.JPG [ 35.58 KiB | Viewed 404 times ]
Top
 Profile  
 
 Post subject: Re: What Wire for AM Loop Antenna?
PostPosted: May Thu 28, 2020 12:20 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 14446
Location: S. Dartmouth MA 02748-1225 USA
Yes, that appears to be L3. L4. The schematic seems to imply that one of the windings is a trap, that, may be the single winding coil that is at right angle.

And yes, this is not a loop but an antenna input coil(s). No amount of nearby induction would couple an RF signal to those coils. They are air core and intended only to match and tune the wire input antenna.

If you are familiar with circuits, trace the windings and the leads to the respective tuning capacitors and switches and see if it conforms to the schematic.

From what I see it should. Then try to determine where the other two leads are or where they should go.

The odd (red) antenna lead that couples to the AC line cord is an optional return to ground via the neutral of the power line. That is not good but when this radio was new using the power line as both an antenna and a ground was possible because there was far less noise. If that connection to the AC line does exist, it would be best to ignore it...

Yes according to the schematic the chassis is ground, however, it is not good again, to use the wall plate as a ground because that circuit has many other devices that create noise bypassed to it. The AC ground is NOT a one way street and will deliver that RF noise to the radio as if it were the antenna :shock: .

Find the correct plug for the Tecsun, I do not own one so I cannot advise. Determine if it is a two, three or four circuit plug so the correct contacts can be made. If you do not want to solder to the plug, it is small work, get an inexpensive short adapter cable of any type or a male to male cable with that plug on the end. Cut the cable some 6 " away from the molded plug, strip the wires and connect the shield wire to the ground from the radio chassis and the center conductor to the white antenna lead. That, assumes the Tecsun to use a two circuit jack.

FWIK about the Tecsun measuring the windings will be from the shell of the connector to the center pin, again assume two circuit, that measurement should be so 10-20 ohms, more of less. When the stripped plug is inserted the same resistance should appear at the two stripped wires.

The Tecsun should now resonate properly for the BC band, turn the tuning condenser on the Tecsum to peak for any station tuned on the radio0...

Pictures of the chassis would confirm the radio has a power transformer and what the tube line-up is.

That said do not connect the chassis ground connection if this radio does not have a power transformer there would be a risk of contacting line voltage at the Tecsun.

Hm, it may be prudent to use the ohmmeter to confirm that the antenna coils have continuity. Occasionally these coils fail from either corrosion or from a nearby pulse created from a lightning strike. Typical resistance should be no more than 50 ohms for the larger coil, less is generally O.K...

The Tecsun will not resonate on shortwave band but may provide some signal input.

Chas

_________________
List' & I will Enchant Thine Ear


Top
 Profile  
 
 Post subject: Re: What Wire for AM Loop Antenna?
PostPosted: May Thu 28, 2020 2:43 am 
Member
User avatar

Joined: Aug Sun 02, 2015 7:34 pm
Posts: 936
Location: Yukon, OK USA
You guys got me interested in building a loop antenna. I have some oak that can be cut down and used. Then looking around for a base I found a spare cast iron base from an Emerson fan with a pivot shaft on top. <edit; moving picture to new topic>

_________________
Rick
AB5ON

Forest Gumping through life


Last edited by black85vette on May Sat 30, 2020 2:16 pm, edited 1 time in total.

Top
 Profile  
 
 Post subject: Re: What Wire for AM Loop Antenna?
PostPosted: May Thu 28, 2020 4:13 am 
Member
User avatar

Joined: May Fri 01, 2020 5:00 pm
Posts: 28
Location: Southern California, USA
Thanks for the trove of info, Chas...amazing. I am a little pressed for "me" time at the moment, but will pull the chassis and post photos as soon as I am able. Thanks again for the great info!


Top
 Profile  
 
Post New Topic Post Reply  [ 32 posts ]  Go to page Previous  1, 2

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 14 guests



Search for:
Jump to:  


































-->


Privacy Policy :: Powered by phpBB