Still Playin' Around..

Hello 12vman,

Very nice picture. I may suggest you one thing... Try to build as many as 30 radials (or, why not, more than 30 radials). I don't know the field strength for 30 radials. I will try to build 15 or 30 radials for my AM transmitter which is Ramsey AM25 transmitter.

I see you have a SWR reflectometer. I would like to buy this one. Can you give me some information about your reflectometer.

Regards and good luck with your part15 project.
Yves Roy

That field strength/v.s.w.r. meter is just an el'cheepo from Radio Shack. There's nothing precise or accurate in the way I'm using it. It just shows that there is stuff happenin' around the base of the antenna. I could see peaks on it but the relative levels changed when I moved away from the area. The easiest way is with the voltage meter at the test points but it's tricky too..

Well, guys. I moved the antenna to my wooden tower/platform that is 20' off of the ground. When it was mounted in the above situation, (in the pics above) I had no problem getting a 13 volt "peak" at the test points on the board. Now since it's away from the chicken wire, the highest peak I can get is around 5 volts and the range didn't change much. I have a very good earth ground connected to the xmtr but the voltage doesn't change much if i connect/disconnect it from the unit..

I thinks I needs to get some of that chicken wire up there on that tower.. 8)

please let us know 🙂

Anyways, I put chicken wire all over the deck area and got the voltage to increase to around 7 volts.. Still not as good as it was on the ground.. 🙁

I had more exposed ground area in the first install. I'll try to increase it where it's at.. As Arnold would say.. "I'll Be Back".. 8)

Two things:

I zoomed in on your #1 picture above as far as the resolution allows and I didn't see the antenna length adjustment mechanism that is called for in the plans. Maybe it's there and I just can't see it. This is a critical feature of the antenna. Selecting the best tap is the first step. Then adjusting the antenna length for best peak is the important second, fine-tuning step.

Wire mesh lying on the ground as shown is not a good way to create an antenna ground. It might be if the wire mesh area is extremely large. You need a conductive path to ground. This can be achieved by a combination of ground rods and BURIED bare-copper radial ground wires, the longer the better, to achieve low resistance conductivity to the soil. Generally the average moisture content of your area is a factor in determining the ground conductivity. If the top few inches of the soil is usually dry, you need to go deeper. 8' electrical ground rods driven vertically are a good way to get down to moist soil.

Two things:

I zoomed in on your #1 picture above as far as the resolution allows and I didn't see the antenna length adjustment mechanism that is called for in the plans. Maybe it's there and I just can't see it. This is a critical feature of the antenna. Selecting the best tap is the first step. Then adjusting the antenna length for best peak is the important second, fine-tuning step.

Wire mesh lying on the ground as shown is not a good way to create an antenna ground. It might be if the wire mesh area is extremely large. You need a conductive path to ground. This can be achieved by a combination of ground rods and BURIED bare-copper radial ground wires, the longer the better, to achieve low resistance conductivity to the soil. Generally the average moisture content of your area is a factor in determining the ground conductivity. If the top few inches of the soil is usually dry, you need to go deeper. 8' electrical ground rods driven vertically are a good way to get down to moist soil.

You can't see it but there is a ground rod connected to the chicken wire and the xmtr. I picked this spot because it has grass growing and keeps moist. I soldered everything togather. Even where the chicken wire crosses each other I soldered them togather including the connection to the ground rod.. That was fun..lol I soldered a short piece of copper wire to the ground rod before pounding it into the ground so I know I have connection to it..

I have the adjustment there. I may suggest an improvment to it. I'll try it on the next one..

Take a piece of the 1/2" copper pipe about 12" long and make 1 cut the length on one side. Now you can spread it open some and it will fit over the bottom of the top adjusting element. Bump it up over the upper element untill it's flush to the bottom. Sweat it in a couple of places so it don't slide up and down while adjusting. This fills the gap between the 1/2" and the 3/4" pipe. Now all you need to do is cut one slot in the 3/4" pipe and maybe only need 1 clamp. A file is needed to get the burrs from the cut on the 1/2" "filler" piece to get a good fit. I haven't tried it yet but it sure does look like it would work great..

I believe I have the xmtr end pretty much figured out.. 8)

I'm using a 12/24 volt converter for the power supply. The SSTRAN uses an 18 volt A.C. "Wall Wart" but after it's rectified and filtered on the board, the D.C. level can go as high as 28 volts. (hmmm...) The 24 volt converter rides around 26 volts (unloaded) so I figured that would be safe.

I also installed an F.M. rcvr in with the mix for the audio link from the house to the xmtr. On this I use a 5 volt regulator for the 24 volt supply for the rcvr. The rcvr is just an el'cheapo mono F.M. radio with an actual "click" on-off switch so if I need to power things down I won't need to climb my tower to turn it back on. It uses 3 "AA" batteries for it's original supply (4.5 volts) but I figured a 1/2 volt extra wouldn't hurt.

I did a test last night and I was very happy with the results. I didn't have everything mounted in its' positions but I can see that it will work sweet! The issues I had with using an inverter are gone for the most part. The F.M. link xmtr already operates on 12 volts D.C. so that wasn't ever an issue but when the SSTRAN and the mixer board were connected to the inverter, I always had a background "buzz" that would never go away. I use a ground loop isolator between the board and the F.M. xmtr and that sure helped. I tried to figured how to operate the board on D.C. but there are +/- supplies in there and there is no easy way to do it so I'm kinda stuck but that's ok. Most of the equipment I'll be using on that end will operate on A.C. anyway.

To sum it up, the only lead I'll have running from the house to the xmtr will be a 12 volt D.C. supply. I'll have part-15 legal F.M. stereo coverage around the grounds and will rebroadcast part-15 legal A.M. for distance but I've created another problem.. 🙁 I use an antenna for television and that F.M. xmtr tears the crap out of my TV! I'll work on that one later..

A couple of updates.. 8)

I had an issue with the FM getting into the board. I (had) an isolator between the board and the FM xmtr but found if the ground is complete by using a standard audio cable takes it away.. KEWL!!

Also, the unit at the top of the tower.. (FM rcvr, AM xmtr) draws less than 200ma (.200 amp) in full modulation! That means around 5 amp/hr. per day. I figure a small solar powered system could be set up for that. It could be a "Stand Alone" xmtr with some kind of link connected to it!

Just some food for thought.. 😉

12v man,

I like the idea of solar power. Since you have more expertise in this area what would you recommend for such a setup? I was thinking of a 20 watt panel connected to a 50 AH battery. That would seem to allow plenty of reserve capacity even for several cloudy days in a row. Since I've not done this before, do you think a charge controller is necessary at this power level or would a blocking diode suffice?

It would certainly be less expensive than paying a basic connect charge to a utility for each transmitter site. Everything could be mounted high enough to avoid most vandalism. It would also be a selling point to community officials for support as it could provide communications during a power failure. (The nearest commerical station to us that has backup power is 75 miles away.)

I always like to "Overkill" some just to be safe..

I figure a "Charge Zone" between the hours of 10 am till 2 pm as prime charging time. All other charge is just a bonus. With a 20 watt panel in 4 hrs. (with good sunlight) would produce about 6-7 amp hrs. Even with cloudy conditions you should collect at least 2-3 all day. That would work but the battery is a little big. The battery should cycle a little so the plates don't get built up if you're using a lead-acid battery. (I don't like gell cells)

I'd figure somewhere in the 15/20 amp/hr rating. There's enough panel to bring it back to full if it's 1/3 drained in a good day and still could operate for at least 2 days with snow covered panels when fully charged. The battery gets a work out but that's what it needs. Cold temperatures won't affect it as bad because the acid is getting sturred around some by the charging/discharging cycle. Too big of a battery will learn a power curve and loose a lot of it's capacity in a year from not working.

Yep.. I would put a charge controller on it. Too much voltage will boil the battery dry. Just for a little more money you can get a one with PWM charging that helps with the plates from getting built up and making the battery last longer with a deeper charge. I use this type in my home and haven't the need to add water to my batteries in over a year. I load test them and there as good as new being 2 yrs. old

Also, the link of choice would need to be added in to the equation as well. I'm using a cheep pocket radio and I'm sure those links may use a little more..

I found this link about building your own solar generator. It seems to be more at using with an inverter to power computers and other appliances, and is probably overkill for a small transmitter.

However, the instructions make it seem quite easy.

http://www.rain.org/~philfear/how2solar.html

Perhaps we could start a new thread about going solar where people who understand these systems could share their knowledge with those of us who don't.

Regards,

Scott
Omaha, NE