I hooked my 12v power supply back up to the transmitter and am having an issue. Before, when I was running on 7.5 volts, everything was fine. Now that Im running at the full 12v the heatsink that the resistor is mounted to is getting hot as hell!!! And, there's a bit of warmth coming from the transmitter. Is this OK?
Would be a good idea to take one of those 12v brushless fans and cool down the hot components. You could mount the amplifier into a metal box and let the fan blow air through the box. There are many companies that sell project boxes with built in fans or a hole to mount one.
It's rare when RF amplifiers don't run warm. Most continuous duty amplifiers built for FM broadcasting are well fanned down and use large heatsinks where possible.
As long as your amplifier is designed to run on 12vdc and running under proper conditions like low SWR, correct amount of input power, and so on then it should be fine but fanning it down is always a good idea.
I acquired an SWR meter and on full power with a tuned ground plane I get 1.25. However, when I reduce the RF output the SWR sky rockets.
Another peculiar thing I noticed: When the transmitter has fully heated up from operating on reduced RF output, and when the RF power is turned back to maximum, the output power is reduced. As the transmitter begins to cool off (I put an ice pack on it), you can see the output power creep back up.
I was planning to make a j pole antenna out of copper pipe, but since the ground plane seems to be pretty efficient when tuned properly I'm wondering if it's worth it. Do I remember correctly that someone said it offers more gain?
I was planning to make a j pole antenna out of copper pipe, but since the ground plane seems to be pretty efficient when tuned properly I'm wondering if it's worth it. Do I remember correctly that someone said it offers more gain?
The GP 1/4 wave antenna may offer good SWR and easy construction but trust me when using a more efficient antenna like a jpole or 5/8 wave antenna the extra cost and time building it pays off more than any extra transmitter gear or transmitter tuneup can do. AKA the old rule of thumb.. antenna > transmitter.
The GP antenna doesn't have much of a gain over a simple dipole. However the jpole basic design has a gain of around 3 or higher. wish is equivalent to doubling your transmitter power or higher.
If using a stacked jpole it's even possible to double that figure or more of the original 3db figure, which means quadrupling your received transmit power.
Groundplane antennas are the most basic type of antenna to build besides a dipole. One of the first antennas I built was a 1/4 GP and even though it had near perfect SWR and high up in the air, it couldn't even compete with my later Jpole antenna even when slightly mismatched and low to the dirt.
5/8 wave antennas are on the same line. They are also good vertical antennas and in my opinion compete about equivalent, however a jpole is always easier to design and much more cost effective if done correctly.
The gain of either antenna is well worth it. However most here will probably agree that the Jpole is the winner unless you are trying to direct your signal towards one direction in which case a beam antenna would beat the others.
What it takes to design the antenna takes some testing. It's really NOT a project to cut and solder and put up in the air and expect to work flawlessly first time. The Jpole is finicky and responds badly to near by metal objects. Keep it away from metal, and a half wavelength away from the tower.
You will literally have to run a low power transmitter into your antenna and screw around with it while looking at an SWR meter. It's not a plug and play type of setup which is why even some Ham radio operators hate the antenna It's a put on site, tune up on site, design on site antenna. But trust me, you do it right, it's more than worth it. Your peon signal will come out looking like the big guys. Or you will get pissed off and stomp on it heh.
Trust me and others here who will probably agree with me, if a jpole doesn't work well for you, you didn't build it right, or screw around with it enough to setup the areal properly. A good jpole will rival most all other vertical antennas, 5/8 wave comes in second place for best of the best.
Thanks for your in depth explanation. Sounds like the j pole is the way to go. What makes it so finicky other than having to keep it away from metal ojbects? The youtube videos and tutorials I've seen online are specific about parts and lenghts. One video said to tune it by moving the wire clamps up and down the pipe.
One video said to tune it by moving the wire clamps up and down the pipe.
That is one of the methods to tune a j-pole. The other method is to build the antenna so that the main element (long piece) and the stub element (short piece) have a section at the tops that can retract or extend to change their lengths a bit, secured by the use of hose clamps or a locking screw. Usually tuning the elements themselves are best since moving the feedline clamps up and down to tune will change the loading impedance.
The use of an antenna bridge is quite handy for this, and saves a ton of hair pulling, stomping frustration and sore feet. With an antenna bridge, you can tune up a j-pole in just a few minutes compared to blindfolded flying.
Well it wasn't too bad. I used 3/4 copper pipe for stability and the process seemed to go smoothly. I was able to get the SWR down to 1.4, but that was with it sitting in my office in close proximity to electronics. I'm sure when I move it outside I'll get better results...
I was able to get the SWR down to 1.4, but that was with it sitting in my office in close proximity to electronics. I'm sure when I move it outside I'll get better results...
Indeed. The results will be different....and could go either way. Expect to spend a little bit of time tweaking and peaking once the j-pole is put into place. Hopefully it will be pretty close and be quick to tune up.
Peace!
K-ROCKS RadioOne
ZeroPointRadio
AM Stereo 1670
FM Stereo 92.1
Post by HighMountainRadio on Jan 12, 2018 19:04:24 GMT -6
Greetings Brother !
I have been doing this on and off since 1970 without incident. Basically follow what the others mentioned, keep it clean, non-controversial and make it sound as best as humanly possible using an equalizer or mixer that can tailor your audio, I use the Xenyx Model 1002FX which is a mixer, equalizer, special effects processor which can be had for less than $100.00 brand new. It is made VERY well and works terrific ! Make it sound as close to commercial radio quality as you can afford, it doesn't take much to get it sounding excellent on a limited budget. Be sure to try not to piss off anyone and if you should perhaps have an RFI issue with a neighbor, do your absolute best to quickly rectify the situation. Not all TV's. radios, et al., are created equal ! My Vizio TV upstairs is a newer smart tv and when I fire up the 40 watt transmitter with attic antenna you can't turn on the upstairs tv, it will not power on due to RFI.. I rectified that situation with the cheap application of 'snap on' ferrite RFI filters on the HDMI cable coming from the cable box and one for good measure on the power cord input to the set, it fixed that issue.. I also get into the landline phone line in my house, that will also be rectified this weekend with the addition of cheap RFI filters made for said purpose. I can muster 80 watts using homebrew 80 watt HPA but I only drive it modestly with a low power, 3 watt exciter which produces 40 watts at the antenna. I live in a mountainous area and get 10 miles out of it with 40 watts, quite satisfactory considering the antenna is in my attic ! I do plan to put the antenna outside soon and camouflage it by extending the ground plane main vertical element and radial length using plexiglas rod extensions to each of the 5 elements to make the antenna 'appear' to be used for a much lower frequency. Painting the plastic rods with aluminum paint to make it blend with the aluminum color of the metal tubing is an excellent 'covert' way to have it outside without garnering undue attention. A trained professional can spot an FM broadcast antenna a mile away by it's length and/or appearance ! I personally don't see you being busted anytime soon, bgut that is simply my humble opinion. Like 'they' say, Never Say Never.. Let that be your guide and rock on brother ! Please do come back here often, there are many very well educated guys on here more than willing to help in any way necessary ! It's a great group of like-minded individuals !
73, Spooky...
"Knowledge Is Always Made More Valuable By Sharing It With Others !" Always Remember To Be Kind ! True Greatness Often Has Very Humble Beginnings ! Help A Kid Out Today ! *** High Mountain Radio *** "Broadcasting From Somewhere High In The Remote Appalachian Mountains"
Post by HighMountainRadio on Jan 12, 2018 19:05:21 GMT -6
Greetings Brother !
I have been doing this on and off since 1970 without incident. Basically follow what the others mentioned, keep it clean, non-controversial and make it sound as best as humanly possible using an equalizer or mixer that can tailor your audio, I use the Xenyx Model 1002FX which is a mixer, equalizer, special effects processor which can be had for less than $100.00 brand new. It is made VERY well and works terrific ! Make it sound as close to commercial radio quality as you can afford, it doesn't take much to get it sounding excellent on a limited budget. Be sure to try not to piss off anyone and if you should perhaps have an RFI issue with a neighbor, do your absolute best to quickly rectify the situation. Not all TV's. radios, et al., are created equal ! My Vizio TV upstairs is a newer smart tv and when I fire up the 40 watt transmitter with attic antenna you can't turn on the upstairs tv, it will not power on due to RFI.. I rectified that situation with the cheap application of 'snap on' ferrite RFI filters on the HDMI cable coming from the cable box and one for good measure on the power cord input to the set, it fixed that issue.. I also get into the landline phone line in my house, that will also be rectified this weekend with the addition of cheap RFI filters made for said purpose. I can muster 80 watts using homebrew 80 watt HPA but I only drive it modestly with a low power, 3 watt exciter which produces 40 watts at the antenna. I live in a mountainous area and get 10 miles out of it with 40 watts, quite satisfactory considering the antenna is in my attic ! I do plan to put the antenna outside soon and camouflage it by extending the ground plane main vertical element and radial length using plexiglas rod extensions to each of the 5 elements to make the antenna 'appear' to be used for a much lower frequency. Painting the plastic rods with aluminum paint to make it blend with the aluminum color of the metal tubing is an excellent 'covert' way to have it outside without garnering undue attention. A trained professional can spot an FM broadcast antenna a mile away by it's length and/or appearance ! I personally don't see you being busted anytime soon, bgut that is simply my humble opinion. Like 'they' say, Never Say Never.. Let that be your guide and rock on brother ! Please do come back here often, there are many very well educated guys on here more than willing to help in any way necessary ! It's a great group of like-minded individuals !
73, Spooky...
"Knowledge Is Always Made More Valuable By Sharing It With Others !" Always Remember To Be Kind ! True Greatness Often Has Very Humble Beginnings ! Help A Kid Out Today ! *** High Mountain Radio *** "Broadcasting From Somewhere High In The Remote Appalachian Mountains"
Post by HighMountainRadio on Feb 4, 2018 7:40:50 GMT -6
Greetings Alcyone !
Regarding your HLLY 5 watt transmitter, it most likely utilizes a Mitsubishi RD06HFV1 as the final output RF amp. If you simply retrofit the transmitter, replacing the RD06HFV1 MOSFET with a Mitsubishi RD15HFV1 MOSFET will give you, theoretically, 15 watts out RF output in high power mode without doing anything else ! From my observations with these types of transmitters you more than likely will see more like 10 watts RF output, thus doubling your output power on the cheap ! You may actually get a wee bit more RF output, perhaps as high as 12 watts, ideally. I have included some images of what the transmitter's board likely looks like, these transmitters of this variety all use the same circuit board with minor differences. Please let us know if you make this mod and the realized results !
73... Spooky...
Attachments:
"Knowledge Is Always Made More Valuable By Sharing It With Others !" Always Remember To Be Kind ! True Greatness Often Has Very Humble Beginnings ! Help A Kid Out Today ! *** High Mountain Radio *** "Broadcasting From Somewhere High In The Remote Appalachian Mountains"
Post by HighMountainRadio on Feb 5, 2018 17:21:14 GMT -6
The part number is most likely Mitsubishi RD06HFV1 for their 5 watt transmitters. If you simply replace it with a Mits RD15HVF1 you will increase your high power output to around 10 ~ 12 watts.. :-)
Spooky...
"Knowledge Is Always Made More Valuable By Sharing It With Others !" Always Remember To Be Kind ! True Greatness Often Has Very Humble Beginnings ! Help A Kid Out Today ! *** High Mountain Radio *** "Broadcasting From Somewhere High In The Remote Appalachian Mountains"
If you were getting only a 3-mile radius from 5 watts, you likely had a near infinate SWR on that antenna.
10 watt resistor you're using now as a dummy load.... please tell me it's not the white ceramic ones? Tou need a special non-inductive resistor for those frequencies.
As for caught or busted, that depends on so many factors, no one can honestly answer this for you I'm afraid :-\
Peace!
I agree with you, I have Ramsey FM transmitter that does 1 watt and with the Ramsey ground plane antenna I can hear the station out to 3 miles radius when out cruising around. I decided to wait until I moved further out into the country side to use this transmitter.