The AM Forum

I'm getting ready to do some RX antenna testing and have a question.
I wonder if any of you K9AY users ever tried to terminate the unselected loop to a resistive load?
I plan to start with 1 K9AY loop on one side of the yard with a short beverage on the other

I'm not completely sure what you mean but I'll say no. Could you tell us more?

Since the unselected loop is 90 degrees off the selected loop why not turn signals coming in off the sides into heat????

What good would that do?

Limit coupling to the loop in use. I might try to simulate it.

Interesting. I wonder what the interaction between the two is?

I ran into K9AY at Dayton this spring.  He was headed to a forum or something and didn't have a lot of time to chit-chat, but he did answer a couple of questions about the loop.  He said to e-mail him and he would be glad to answer any other questions in detail.

Since the loops are not resonant and mounted at 90 degree angles it doesn't seem there would be much coupling. If it were an issue it would probably show up in modeling.

Agree but would it suck down the field strength with the loop terminated to a load converting to heat. I bet it will also require a change to the selected loop load value.

I don't think the loop will act as a dummy load. However, it would be interesting to see what would happen if you fed and terminated both loops and played some phasing games.

I have played these games near field so wonder if it works with antennas.
I've effected emissions of cables by adding ground wires in the bundle.

Dummies are people too.... :'(

They sure are.

A lesson I learned from my K9AY is to keep it FAR AWAY from the transmitting antenna. The TX RF never hurt the pre-amp for the loop but it fried the usual coil in my R390A. I forget the circuit deignation but it is the first coil used on the broadcast to 2mc in the RF deck.

I have since installed an I.C.E. RF limiter on the R390A and an early Spring thunder storm wiped that out. So my 390A has been saved.

Slight off-topic
Fred

And you'll want separation to avoid pattern distortion and/or noise reradiated from the TX antenna.

I tried the AY loop years ago and the 2 turn shielded, remotely tuned, and rotatable loop beat it every time. And of course it didnt come close to a full size Beverage.

Get some of those brass Slinkys and stretch 4-5 out over 150-200'. Ive had one up to the NE that equals a 1200' for SNR but the gain (loss really) is a bit more wih the Slinky. Use a carbon pot to determine the best F/B off a high end BC station during the day then use a fixed 2W; I found 1200 Ohms works best but Im on mostly rock covered by some sand and pine needles, the ground rod goes in at a very shallow angle.

Carl

I spent the past week playing with different KAZ configurations compared to a 160 foot beverage. The beverage was 160 feet long pointing west and the KAZ was set up to go east.  The larger I made the KAZ the lower frequency the pattern flipped. I had a 85 foot base KAZ 30 feet tall pick up WWVH on 10 and 15 MHz better than the beverage. This was off the load end.
I didn't try the K9AY because HUZ told me his didn't work well on 40 meters.
My last configuration of the KAZ was 50 foot base and 30 feet at the apex. On 40 meters is was no better than the beverage in either direction yet worked well below about 5 MHz.
My first KAZ worked best on 40M since it was the smallest. I need to go smaller yet. The noise floor is not a problem so can get away without an amp. My coax run was too short to go smaller. Next trip I will bring more feed line so I don't have to come in the kitchen window and block the XYL's area.

I really like my K9AY but I'm starting to wonder if it's working just right.....

 If I'm receiving a signal from the EAST, when I switch between NE and SE, there isn't much difference in signal strength.  However, if I switch to either NW or SW, then there is a pretty large (12 to 18 dB) of difference.  Does this sound right or might I have a problem with my K9AY?

I would get the same results with my 9AY. It seems sometimes it does magic and sometimes no difference. I'm not an official knowledgebase on the 9AY loop. I have experienced the same thing.
Maybe some other responses.
I'm not sure even a HB rotateable loop would give same results. Any predictability to traditional beverages??Something about the RX sig coming from sky wave or ground waves..................dunno

Fred

I'm only using 1 loop so far but notice signals off the side stronger as you increase frequency. I read the EWE pattern also shifts as you increase frequency. I think the null is a bigger deal than gain in the k9ay

Seems correct to me. The front lobe is very broad so there is overlap between the different directions. But the null on the back side of the pattern can be pretty substantial.

Dragged some more coax to GFZ south and flipped the KAZ to the west. Also reduced the sice to about 20 feet on a side. I would say 90% of the time WWVH (5, 10, 15 MHz) came in better on the KAZ than the beverage. MW band the BEV always won. They were about even off the back side to the east. The KAZ was also quieter. Next time I will make the KAZ a lot bigger and see what happens.
I also tried a single K9AY loop and found it not very directive on 40 meters compared to the beverage.

Most any terminated loop will lose directivity when its length approaches 0.25 WL at the operating frequency.

HUZ I think it loses directivity when the two vertical wires approach .25 WL.
Also the pattern flips when it gets a lot longer. I want to play with a larger one some more to see how it plays against the beverage to the west. Two weeks ago I didn't have enough coax with me to get them both in the same direction.

It's the circumference. If it's around 0.25 WL the directivity is gone. Once the loop is larger than this, the E and H-fields cannot be balanced and subtracted. Bye-bye directivity.

Here's an audio clip of my K9AY in action on 1590 kHz.

So I should go smaller yet not larger, interesting.
The smallesr one was about 20 feet on a side. the beverage always won on mw but the KAZ took over above that. There wasn't a lot of activity on 160 and 75 the past two weeks so didn't get a chance to do a lot of testing there. So concentrated on WWV and WWVH with some 40 m SW. The bands were kind of dead after the solar event. 

Try WWV at 2.5 MHz.