I recently acquired a Conar radio that was made from a National Radio Institute kit back in the mid 60’s. It was quite messed up, and while working without a schematic, I have it working. The problem is the antenna was a coil over a ferrite rod, and the rod is broke into three pieces. I purchased a 230 µH 4.25” X 11/32 Ferrite rod unit from AES. This antenna only gives about half power until I grab the coil with my hand, then the radio plays real loud on all stations across the dial, but when I let go of the coil I loose a lot of volume.

I also have an oval loop antenna 270 µH antenna from AES for another project. When I use jumpers to connect this antenna the radio plays real good. There is no room in the cabinet for the oval loop. What can I do to get the rod antenna to work better? Thanks for any help in advance.

:I recently acquired a Conar radio that was made from a National Radio Institute kit back in the mid 60’s. It was quite messed up, and while working without a schematic, I have it working. The problem is the antenna was a coil over a ferrite rod, and the rod is broke into three pieces. I purchased a 230 µH 4.25” X 11/32 Ferrite rod unit from AES. This antenna only gives about half power until I grab the coil with my hand, then the radio plays real loud on all stations across the dial, but when I let go of the coil I loose a lot of volume.
:
:I also have an oval loop antenna 270 µH antenna from AES for another project. When I use jumpers to connect this antenna the radio plays real good. There is no room in the cabinet for the oval loop. What can I do to get the rod antenna to work better? Thanks for any help in advance.
:

Hi Doug,
When you place your hand on the ferrite rod you may be making yourself an antenna or adding capacitance. Try tuning the input circuit of the radio to the new rod. If the tuning bottoms out add low capacity capacitors so that the tuning peaks around the middle. Added capacitors would be, around 22-47pf if you need them.

Best Regards,

Bill Grimm

Why not just glue the original rod back together with super glue???????????????????????????? It'll work fine. I bet $50 that it will.

Thomas

:Why not just glue the original rod back together with super glue???????????????????????????? It'll work fine. I bet $50 that it will.
:
:Thomas

I am with Thomas on this one, glue it back together.

Dave

....because typically ferrite rod antennas are composed of an iron powder mixture that doesn't conduct electrically. This is to reduce losses caused by eddy currents--what happens when a big chunk of metal is put in a fluctuating magnetic field. Gluing the ferrite rod back together isn't going to be much more electrically different than the original binder (whatever that may be) that holds the rod together in the first place.

T.

Thanks, guys,

I will try suggestions. There is a small capacitor (25MMFD) already in the circuit between the antenna lead and tuning cap. I may try to wire in around that first or I may have to go to 47MMFD. I will figure it out.
Thanks again, Doug H.

Could we assume your original loop to be having a long rod in the nature of 7 or possibly 5 inches in length. It seems that the one that you purchased from AES, is in the order of ~ 4 7/8 inches with a 5/16 dia rod. Also quite a few of the older ones had the coil winding right on the rod proper and was spread out almost all of its length. Later they would have the winding upon a form and it covering no more that a mere third of the rods length.

Sooooo since you have already bought the farm, with your first installment of $8.96 + on that loop.

Lets check out this possibility, since we know that the present L/C match is in error and needs to be adjusted with a shifting of the L value and not appreciably bothering the factory selected C value adjustment. Inspect the unit to see if the common mode of the utilization of yellow bees wax or clear parrafin wax was used by the manufacturer for the final securing of the positioning of that slide able coil forms position on the ferrite rod element. What you would want to do is use the heat of a hair dryer to soften it to the extent that it can be moved laterally, then flip the dryer aside while continually keeping it moving back and forth so as to not let the wax reset and lock it down again. With the coil then being able to be moved, fire up ye olden ray-dee-oo and tune to a weaker station ~ close to 1300 . Next you touch the coil at the end of the form where any finger touching will be made to the form and not the coil proper. Then you see if the sliding of a that coil form in either direction will make the station peak and then weaken down if passing past that peak reception point. You want that positioning to be occurring at least before the end of the rod in one direction or at LESS than the center of the loop position in the other direction.
Usually the factory designs for an ~ 1/4 to 1/3 positioning from the end of the rod to acquire its desired inductive value.
A final tweaking would be the positioning of the coil form with a right/ left lever action with a plastic/wooden stick / dowel to peak to the optimum position without any possibility of finger/hand capacitance shifting the L/C pairs.static resonance point.

Thats it.

Follow the recommended alignment procedure IF even deemed necessary or come back with more info on the radios front end circuitry.

One could only expect slightly better performance with the longer 7 in rod, should your old unit not using be the looooong over wound type of coil construction.

Broken ferrite element...repair ? In the past, in RF laboratory environs, getting empirical results, I have evaluated repair of a center, clean broken rod and its rejoining with both epoxy and the cyanoacrylate family of adhesives. The inherent minimum attainable filler thickness of the more viscous epoxy made the thinner film possible with the cyanoacrylate family the obviously clear choice. (While using a tensioned clamping also.) The testing of the resultant "Q" of the rebuilt inductor when using that core displayed a marked drop in value as compared to an unimpaired reference unit. The repair of two breaks...say into thirds.... would yield an APPRECIABLE drop in "Q".
In retrospect, within a mechanical aspect, the strength of that bond would be favoring a longitudinal stressing...push-pull...whereas its lateral strength...right-left….tensioning is appreciably less, much as it was, in the original failure mode of the rod.
Final observation:
However close the co-joining of the broken elements , the degree of uniform inter dispersion of the magnetic elements could not approach the normal elemental spacing on an unimpaired unit. There was always the distinct, uniform sheer stress line/separation presented all across the inductor at that repair point, where the inter magnetic coupling was deficient.

73's de Edd

:Could we assume your original loop to be having a long rod in the nature of 7 or possibly 5 inches in length. It seems that the one that you purchased from AES, is in the order of ~ 4 7/8 inches with a 5/16 dia rod. Also quite a few of the older ones had the coil winding right on the rod proper and was spread out almost all of its length. Later they would have the winding upon a form and it covering no more that a mere third of the rods length.
:
:Sooooo since you have already bought the farm, with your first installment of $8.96 + on that loop.
:
:Lets check out this possibility, since we know that the present L/C match is in error and needs to be adjusted with a shifting of the L value and not appreciably bothering the factory selected C value adjustment. Inspect the unit to see if the common mode of the utilization of yellow bees wax or clear parrafin wax was used by the manufacturer for the final securing of the positioning of that slide able coil forms position on the ferrite rod element. What you would want to do is use the heat of a hair dryer to soften it to the extent that it can be moved laterally, then flip the dryer aside while continually keeping it moving back and forth so as to not let the wax reset and lock it down again. With the coil then being able to be moved, fire up ye olden ray-dee-oo and tune to a weaker station ~ close to 1300 . Next you touch the coil at the end of the form where any finger touching will be made to the form and not the coil proper. Then you see if the sliding of a that coil form in either direction will make the station peak and then weaken down if passing past that peak reception point. You want that positioning to be occurring at least before the end of the rod in one direction or at LESS than the center of the loop position in the other direction.
:Usually the factory designs for an ~ 1/4 to 1/3 positioning from the end of the rod to acquire its desired inductive value.
:A final tweaking would be the positioning of the coil form with a right/ left lever action with a plastic/wooden stick / dowel to peak to the optimum position without any possibility of finger/hand capacitance shifting the L/C pairs.static resonance point.
:
:Thats it.
:
:Follow the recommended alignment procedure IF even deemed necessary or come back with more info on the radios front end circuitry.
:
:One could only expect slightly better performance with the longer 7 in rod, should your old unit not using be the looooong over wound type of coil construction.
:
:Broken ferrite element...repair ? In the past, in RF laboratory environs, getting empirical results, I have evaluated repair of a center, clean broken rod and its rejoining with both epoxy and the cyanoacrylate family of adhesives. The inherent minimum attainable filler thickness of the more viscous epoxy made the thinner film possible with the cyanoacrylate family the obviously clear choice. (While using a tensioned clamping also.) The testing of the resultant "Q" of the rebuilt inductor when using that core displayed a marked drop in value as compared to an unimpaired reference unit. The repair of two breaks...say into thirds.... would yield an APPRECIABLE drop in "Q".
:In retrospect, within a mechanical aspect, the strength of that bond would be favoring a longitudinal stressing...push-pull...whereas its lateral strength...right-left….tensioning is appreciably less, much as it was, in the original failure mode of the rod.
:Final observation:
:However close the co-joining of the broken elements , the degree of uniform inter dispersion of the magnetic elements could not approach the normal elemental spacing on an unimpaired unit. There was always the distinct, uniform sheer stress line/separation presented all across the inductor at that repair point, where the inter magnetic coupling was deficient.
:
:73's de Edd
:

Edd

I am a bit curious as to the testing method you used, do you have a comparison of the results of the "Q" at different frequencies. I had had good success with simply gluing the ferrite rod. I have a ferrite I just may measure and break and remeasure to verify the results. As the nature of the ferrite is to insulate the magnetic particles I really see no reason gluing wouldn't work just fine.

Dave

ER8,
Could it be that we're referring to a simple powdered iron core with a non conductive binder, to enhance the flux lines and alter the overall inductance of a coil of wire. As a rule, ferrite in and of itself is more suited for the upper end of the RF spectrum ie microwave, where various mixtures produce lumped element devices without a coil of wire. I suggest that secondary to the required inductance, is the actual size of the assembly, and hence the reason a full blown loop antenna performs much better. A loop captures more of a wave front than the small rod fixture, much the same way a large external wire is better than the loop. Search the Salvation Army Thrift Stores for a table model containing a larger (6-8 inches)rod antenna.

marv

::Could we assume your original loop to be having a long rod in the nature of 7 or possibly 5 inches in length. It seems that the one that you purchased from AES, is in the order of ~ 4 7/8 inches with a 5/16 dia rod. Also quite a few of the older ones had the coil winding right on the rod proper and was spread out almost all of its length. Later they would have the winding upon a form and it covering no more that a mere third of the rods length.
::
::Sooooo since you have already bought the farm, with your first installment of $8.96 + on that loop.
::
::Lets check out this possibility, since we know that the present L/C match is in error and needs to be adjusted with a shifting of the L value and not appreciably bothering the factory selected C value adjustment. Inspect the unit to see if the common mode of the utilization of yellow bees wax or clear parrafin wax was used by the manufacturer for the final securing of the positioning of that slide able coil forms position on the ferrite rod element. What you would want to do is use the heat of a hair dryer to soften it to the extent that it can be moved laterally, then flip the dryer aside while continually keeping it moving back and forth so as to not let the wax reset and lock it down again. With the coil then being able to be moved, fire up ye olden ray-dee-oo and tune to a weaker station ~ close to 1300 . Next you touch the coil at the end of the form where any finger touching will be made to the form and not the coil proper. Then you see if the sliding of a that coil form in either direction will make the station peak and then weaken down if passing past that peak reception point. You want that positioning to be occurring at least before the end of the rod in one direction or at LESS than the center of the loop position in the other direction.
::Usually the factory designs for an ~ 1/4 to 1/3 positioning from the end of the rod to acquire its desired inductive value.
::A final tweaking would be the positioning of the coil form with a right/ left lever action with a plastic/wooden stick / dowel to peak to the optimum position without any possibility of finger/hand capacitance shifting the L/C pairs.static resonance point.
::
::Thats it.
::
::Follow the recommended alignment procedure IF even deemed necessary or come back with more info on the radios front end circuitry.
::
::One could only expect slightly better performance with the longer 7 in rod, should your old unit not using be the looooong over wound type of coil construction.
::
::Broken ferrite element...repair ? In the past, in RF laboratory environs, getting empirical results, I have evaluated repair of a center, clean broken rod and its rejoining with both epoxy and the cyanoacrylate family of adhesives. The inherent minimum attainable filler thickness of the more viscous epoxy made the thinner film possible with the cyanoacrylate family the obviously clear choice. (While using a tensioned clamping also.) The testing of the resultant "Q" of the rebuilt inductor when using that core displayed a marked drop in value as compared to an unimpaired reference unit. The repair of two breaks...say into thirds.... would yield an APPRECIABLE drop in "Q".
::In retrospect, within a mechanical aspect, the strength of that bond would be favoring a longitudinal stressing...push-pull...whereas its lateral strength...right-left….tensioning is appreciably less, much as it was, in the original failure mode of the rod.
::Final observation:
::However close the co-joining of the broken elements , the degree of uniform inter dispersion of the magnetic elements could not approach the normal elemental spacing on an unimpaired unit. There was always the distinct, uniform sheer stress line/separation presented all across the inductor at that repair point, where the inter magnetic coupling was deficient.
::
::73's de Edd
::
:
:Edd
:
:I am a bit curious as to the testing method you used, do you have a comparison of the results of the "Q" at different frequencies. I had had good success with simply gluing the ferrite rod. I have a ferrite I just may measure and break and remeasure to verify the results. As the nature of the ferrite is to insulate the magnetic particles I really see no reason gluing wouldn't work just fine.
:
:Dave

What Dave and I are wondering, though, is why everyone's going through all of this trouble instead of simply gluing back together the original antenna. Isn't the original antenna the one the radio came with? Wouldn't everyone think that it's best to stick with what the manufacturer originally specified, so that the radio tracks and operates as it should? I don't understand why everyone is coming up with all of these theories and methods for using a different loopstick, when the simplest solution is to superglue the original stick back together, throw it in the radio, and call it a day.

.....Making more work than there has to be.

....And yes, a longer loopstick has a different impedance than a shorter one, which is why a shorter one, possibly with the same coil size, won't operate the same with the same tuning condenser. You can make the shorter one work with the tuning condenser, by playing around with series and parallel capacitance. Why do it, though, when you can just glue back together the original???????????

T.

My assumptions based on the existing posts, were that the original was broken and the new replacement being smaller, didn't work well unless encompassed with a human hand. Even the original, if glued together will not perform as well as it did initially, and could well require the human hand trick again. Even re-tweaking the set for use with the replacement may still require the human hand trick, simply because of physical size of the winding.

marv

:What Dave and I are wondering, though, is why everyone's going through all of this trouble instead of simply gluing back together the original antenna. Isn't the original antenna the one the radio came with? Wouldn't everyone think that it's best to stick with what the manufacturer originally specified, so that the radio tracks and operates as it should? I don't understand why everyone is coming up with all of these theories and methods for using a different loopstick, when the simplest solution is to superglue the original stick back together, throw it in the radio, and call it a day.
:
:.....Making more work than there has to be.
:
:....And yes, a longer loopstick has a different impedance than a shorter one, which is why a shorter one, possibly with the same coil size, won't operate the same with the same tuning condenser. You can make the shorter one work with the tuning condenser, by playing around with series and parallel capacitance. Why do it, though, when you can just glue back together the original???????????
:
:T.

:My assumptions based on the existing posts, were that the original was broken and the new replacement being smaller, didn't work well unless encompassed with a human hand. Even the original, if glued together will not perform as well as it did initially, and could well require the human hand trick again. Even re-tweaking the set for use with the replacement may still require the human hand trick, simply because of physical size of the winding.
:
:marv
:
::What Dave and I are wondering, though, is why everyone's going through all of this trouble instead of simply gluing back together the original antenna. Isn't the original antenna the one the radio came with? Wouldn't everyone think that it's best to stick with what the manufacturer originally specified, so that the radio tracks and operates as it should? I don't understand why everyone is coming up with all of these theories and methods for using a different loopstick, when the simplest solution is to superglue the original stick back together, throw it in the radio, and call it a day.
::
::.....Making more work than there has to be.
::
::....And yes, a longer loopstick has a different impedance than a shorter one, which is why a shorter one, possibly with the same coil size, won't operate the same with the same tuning condenser. You can make the shorter one work with the tuning condenser, by playing around with series and parallel capacitance. Why do it, though, when you can just glue back together the original???????????
::
::T.

I will get back to this unit this weekend, in the meantime, I have glued one piece back on the old rod antenna, and will glue the second one on tonight. You are right in that the original one is 7 inches in length.

When I received the radio, tubes were in wrong sockets, a wire coil was atached in place of the antenna connected through a 0.1 mfd capacitor. I have no idea why, but the original rod antenna was in three pieces. This rod antenna has four leads coming out at different areas of the small coils which are wound over cardbord hollow cylinder. This cylinder containing the coils is only about one and one half inches long, and can be slid up or down the length of the ferrite rod. I have run continuity test on the four leads to separate the leads into the short windings and longer windings. only one of these leads was soldered to a tuning cap, the other three were hanging loose.

I got the best reception when I connected the two leads from the longest winding to each end of one of the tuning caps, but the other two leads from the short winding are still loose at this time.

I will update when the parts are glued togather and installed. By the way, I have removed the 0.1 mfd cap along with the wire that someone before me had installed. Without the schematic on one of these kit built radios it does get a little confusing.

Thanks, Doug H.

Most AA5 radios are amazingly similar. If you have a good idea of the various AVC circuits and oscillator circuits, antenna circuits, etc., then you should be able to take a little bit of this and that and put the radio back into working order. If quite a bit has been altered in the antenna circuit, you may need to experiment with how the antenna is connected. Typically it is connected directly to grid 3 of the 12BE6 and 12SA7 (along with the large stator of the tuning condenser....sometimes they're both the same size, though). The return may be connected directly to B-, or to some other biasing point, and possibly to the AVC line (high value resistor and filter condenser around .05 to .1 MFD). Some radios only have the IF stage connected to AVC. Others have both the antenna circuit and the IF connected. Some have the two separated by separate AVC resistors. Many others have them both connected together.

The tuning condenser frame may or may not be connected to the AVC line. If no coils connect to the condenser frame, there is no need to bias the condenser, as bias on the condenser serves no purpose, though the condenser can be connected to the AVC line, too, if one wishes. On the other hand, if coils are anchored to the condenser frame, then the condenser must be connected to whatever the coils are supposed to be connected to. Just remember that if the condenser is not part of any DC circuit, it may be connected to any point that is electrically the same as where the antenna coil connects to alternating current wise. If the antenna coil is connected to the AVC line, and the condenser frame happens to be connected to B-, they are still linked together via the .05 MFD AVC filter condenser, as far as radio frequencies are concerned. This paragraph has been written because some radios may have B- connected directly to the chassis (hot chassis), and then the tuning condenser also connected directly to the chassis (more often it is insulated by rubber gromets). This can be kind of confusing as to how on earth it is supposed to have any effect on the antenna coil, when the antenna coil might be anchored elsewhere (such as to the AVC line).

Perhaps the above is too much information, but these are little things that you can think about while you try to solve modifications.

Thomas

::Why not just glue the original rod back together with super glue???????????????????????????? It'll work fine. I bet $50 that it will.
::
::Thomas
:
:I am with Thomas on this one, glue it back together.
:
:Dave

I had assumed that the original ferrite was beyond hope. If it can be fixed, I am with ER8 and Thomas, glue it. The retune will be less than the new one, if retuning is needed at all.

Best Regards,

Bill Grimm

:I recently acquired a Conar radio that was made from a National Radio Institute kit back in the mid 60’s. It was quite messed up, and while working without a schematic, I have it working. The problem is the antenna was a coil over a ferrite rod, and the rod is broke into three pieces. I purchased a 230 µH 4.25” X 11/32 Ferrite rod unit from AES. This antenna only gives about half power until I grab the coil with my hand, then the radio plays real loud on all stations across the dial, but when I let go of the coil I loose a lot of volume.
:
:I also have an oval loop antenna 270 µH antenna from AES for another project. When I use jumpers to connect this antenna the radio plays real good. There is no room in the cabinet for the oval loop. What can I do to get the rod antenna to work better? Thanks for any help in advance.
:

I have just bought an unbuilt kit of this radio. I have the manual with the schematic and setup tips for the ferrite rod antenna, and I could scan them in and E-mail them to you, if you would like, and I'll measure the ferrite rod length. I don't have it in front of me right now, but the manual does tell you how to specifically locate the coil on the rod.

The interesting thing is that not all of the parts are included with the complete kit! You are supposed to have the remaining parts on hand as unused parts of previous kits. They have been easy to obtain with one exception: the osc. coil. It's a 4-lug with color-coded terminals, and no official make or part number is given. Looks like there are 2 coils on the form, according to the pic in the manual.

The stock ferrite rod is 7.5" long. With a station tuned in that's in the middle of the dial, slide the coil back and forth until the signal is strongest.