i have a couple questions, someone might know the answer to,
i plan to hook it up to a 12 volt, 2 amp power brick, does that seem like enough DC?
do I need to enclose it in a metal box or ground out the heatsink? im going to be plugging it into my Ramsay fm30b.
should the thing be grounded to the FM30b?
I don't have a SWR meter of any kind, but I have lots of random audio gear, and coax cables. if you want to trade your old one, let me know what you need?
12 volts * 2 amps is 24 watts DC power so yes that will power it fine at its 6 watt output. I would ground the heat sink but make sure the RF transistor has its electrical insulator in place if needed by the design. All ground points should meet and tie off to the shielded box. I'd mount the Ramsey kit right inside next to the amp to keep the shortest distance of cabling and shared ground points. Any RF power amplifier should be well shielded in a metal enclosure just to be safe with stray RF that can cause feedback, spurious emissions, and even audible broadcast hum or noise. Even at the 6 watt level this will be necessary but you may be able to test it for the time being unshielded until your project comes together. This should be obvious but don't use it without a heat sink or loaded properly with RF input and outputs or you'll let out the magic smoke.
Because you are using the Ramsey transmitter make absolutely sure you run the output through a low pass RF filter. Those kits are known to put out bad harmonic content and can cause serious interference at 5+ watts without it. Better safe than sorry.
Also I don't see anything listed on that ebay site as to how much power it requires to drive the full 6 watt output? The Ramsey will be putting out somewhere around 20mw, so to amplify that to 6 watts it will need some buffer transistor but I don't see that in the pictures.
Kage, thank you for the input I have heard of low pass filters, but there is a lot of variety out there, can you recommend anything specific? also, I have a pile of transistors, do you know offhand which ones are best for my situation? I might be able to dig it out of the box and add it to the Ramsey.
Post by HighMountainRadio on Mar 20, 2018 17:24:43 GMT -6
Greetings Tester !
After thoroughly reviewing all associated information, I see that the 6 watt RF power amplifier requires from .1 ~ .5 watts (.1 watt=100 milliwatts), (.5 watt=500 milliwatts) of RF drive power for minimum to maximum RF output of 6 watts. Since the Ramsey FM30B has a maximum rated output of 25 milliwatts (.025 watt) it is not enough RF drive to even start to tickle the input of the 6 watt RF power amp. In this scenario, no RF amplification from the 6 watt amp will be realized unfortunately. You must drive the 6 watt amp at a minimum of 100 milliwatts to even begin any amplification of the drive signal from the output of the FM30B. An 'intermediate' RF amplifier must be utilized between the FM30B output and the 6 watt RF amp to boost the signal to the necessary RF drive level to produce the minimum to maximum output of the 6 watt amp. It will be necessary to choose an RF amplifier transistor capable of operating within the 88-108 MHz spectrum and safely accept the 25 milliwatt drive level from the FM30B as well as having the necessary gain figure to amplify the 25 milliwatt value to no more than 500 milliwatts, the maximum level the 6 watt amp can safely accept. Be very careful not to overdrive the 6 watt amp as damage could result or at the very least, generate spurious emissions, highly undesirable ! A good 'Low Pass Filter' to suppress unwanted harmonic content on your output can be found here: broadcastconcepts.com/150W-FM-LPF.html for $35.00, a very good price ! Kage has provided solid, accurate info as well !
By the way, I don't see any mention in the 6 watt amp specifications of what RF amplifier transistor is utilized on it. Please message me here that information and I will investigate if a different device may be available that may better suit the situation and still provide the desired 6 watt output without having to do any major re-work of the amp. An educated guess indicates to me that it may very likely be a Mitsubishi RD06HVF1. This device is very commonly utilized in numerous Chinese manufactured FM broadcast transmitters in that RF output range of 5~7 watts. See included 'gain plot' for this device, RF Power Input vs. RF Power Output.
Hope this helps answer your questions in an easy to understand summary. Good luck with your project ! 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"
So, I put the amp in line and went and drove around. It seems like my signal went 5-10 blocks farther depending on what direction I was traveling. Could the Ramsay be tickling it just a scoutch? I was thinking - could the rf chip in the Ramsay be switched out for something more powerful? I spent a lot of money and time on the thing, and it sounds pretty good, but that may be the source material
Have any of you upped the output of a tiny exciter ?
Post by HighMountainRadio on Mar 21, 2018 3:14:23 GMT -6
Good Morning Tester !
Well, I am a very firm believer in 'never say never', so RF being the voodoo it is, anything is possible I suppose ! I found the User Manual for the FM30B online so I will look it over to see what may be able to be done to beef up the output to somewhere in the level it needs to be to properly drive the 6 watt amp. I will be more than happy to work with you to achieve your desired outcome ! I have been in the 'radio game' my entire life, starting at about age 6, it has been my passion for many years ! I'll check back here later. Also, feel free to e-mail me at the listed forum address if you like.
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 Mar 21, 2018 11:57:53 GMT -6
Greeting Tester !
Well, after doing some research I discovered that the FM30B transmitter utilizes a 'GAL-5' RF amplifier device at circuit board position (U8). According to the manufacturer specifications this device has a MAXIMUM RF output power of 475 mw (.475 watts). Modifying the original circuitry of the FM30B to facilitate increased RF output from the GAL-5, closer to it's rated potential is a possibility worth exploring. Obviously, since the manufacturer stated RF output of the transmitter is a maximum of 25 mw, the circuit design throttles this output back from it's maximum capability. The model FM100B utilizes not only the GAL-5 in circuit board position (U6) but additionally an MRF557 at position (Q6) to boost the transmitter's output from 25 mw to 1 watt RF output for use outside of the USA. The USA version of the FM100B has an RF output power of 25 mw. Since I don't have the luxury of being able to find a schematic diagram of either model, the FM30B or the FM100B, it is difficult to immediately ascertain what specific additional components would need to be added to the existing circuitry aside from the MRF557 RF output transistor. Once this can be established and implemented, 1 watt of power would surely be more than enough RF drive level to fully drive the 6 watt RF power amplifier to it's maximum output. In fact, some RF attenuation would need to be included to reduce the 1 watt of drive to no more than the maximum RF input drive to .5 watt, the maximum drive level applied to the input of the 6 watt amplifier. I will continue to research this modification or some other alternate circuitry that may be used to achieve the desired result, stay tuned.. Additionally I plan to research the possibility of simply incorporating a Mitsubishi RD06HVF1 RF amplifier MOSFET, as well as the necessary support circuitry, into the original design circuitry to attain the desired 5-7 watt output level without the need of the 6 watt RF amplifier module entirely. It is entirely conceivable that the FM30B can be modified in this way.
***UPDATE !
Upon further research it has come to my attention that Ramsey provides a kit of parts apparently intended to be added to the existing appropriate circuit board of the FM100B, 25 mw USA version transmitter to boost it's RF output power to a level of 1 watt for use outside of the USA ! Although it would be a fairly moderate undertaking from a technical and mechanical engineering perspective for someone who may not me quite as technically savvy, it isn't impossible to achieve. Since a readily available schematic diagram for this circuit seems to be unavailable anywhere online from my observations, this of course complicates the task. If a schematic can be acquired for the FM100BEX kit, making your own necessary circuit board, using the parts layout diagram, would provide a great educational experience ! The availability of a complete parts kit of the necessary components is quite handy, negating the requirement of having to scrounge all of the components yourself !
While I can thoroughly appreciate all of the time, expense and effort that you have already invested in the Ramsey FM30B, considering all of the above information, it surely would be FAR easier to simply replace the Ramsey FM30B with a quite inexpensive Chinese FM broadcast transmitter of the 5-7 watt variety ! I am fully aware of the negative comments regarding these units available from numerous sources on EBay, however from my own observations, I find the performance of the few models I have had the opportunity of using and personally evaluating to be quite the opposite in reality. I have had very satisfactory results using a 'generic' model ST-15B 5 / 15 watt FM transmitter as well as one of the 7 watt model varieties readily available on EBay from a multitude of resellers. I have found the audio quality to be quite good and easily capable of 24/7 operation over quite extended periods of time without any issues at all ! I have also observed very positive comments made by other users of these units. In my humble opinion, a lot of the negative comments regarding these units stems from the fact that they were not installed and/or matched properly to the transmission line and antenna system in addition to poor quality audio and RF cable being utilized during setup. I have seen several models in the 5~7 watt output power range that are capable of fully adjustable RF output power level. It may be worth exploring this option given the amount of time and effort required to implement any of the above detailed options. If you have the required big bucks budget to consider something better, the AAREFF/Veronica 1 Watt Exciter is a very nice unit worth investigating: www.aareff.com/en/1w-pll-fm-transmitter-kit/ I trust the information provided will permit you to make an informed decision on which way to best proceed.
Perhaps, when Kage has an opportunity to read this information he may offer additional insight or alternative ideas !
"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"
Thanks for bestowing your wisdom Spooky, Thinking about the time and effort involved, I'm considering a new Transmitter / Exciter. would the CZE 500 m watt juice up that RD06HVF1 properly? I found one cheap on EBAY i could Purchase.
Post by HighMountainRadio on Mar 21, 2018 17:27:41 GMT -6
Good Evening Tester !
I believe you meant the CZE-05B transmitter as there is not CZE500 that I am aware of at least. lol ! Yes, indeed, the .5 watt RF output from the CZE transmitter would indeed provide plenty of drive for your 6 watt RF amplifier ! Actually, the maximum drive for the 6 watt amp is .5 watt so care must be taken upon setup to ensure that you don't inadvertently overdrive the 6 watt amp. A wattmeter placed at the output of the CZE transmitter is recommended to ensure that no more than .5 watt is being delivered at it's output. Ideally, it is further recommended to terminate the output of the transmitter into a 50 ohm dummy load when measuring the output power for accuracy. A better choice in transmitters is the Model FU-X01AK sold by FMUser.org. See it here:fmuser.org/fm-transmitter/0---30w-fm-transmitter/FMUSER-NEW-1W-FM-Transmitter-FM-radio-broadcaster-50usd70us-Preemphasis-01w-Power-Output-Adjustable-FUX01A/ This transmitter has a full rated output of a full 1 watt and is 11 step adjustable at the front panel from 0~1 watt output. This would be ideally suited for your purpose if you don't mind spending a bit more. This transmitter also features user selectable audio pre-emphasis, either 50us or 75us (USA Broadcast Standard) ! It can be purchased from them for $129.00 US which includes shipping to USA. All you would have to do is adjust the RF output to just below .5 watt to drive the 6 watt amplifier properly. If you desire less than 6 watts output from the amp all you must do is reduce the output power of the transmitter which is easily done right from the front panel ! Just be certain to NEVER overdrive the RF amplifier by ensuring no more than .5 watt ever reaches it's input. I highly recommend the purchase of an inexpensive VSWR Bridge (Also known as a SWR Meter). This will allow you to measure the VSWR (Standing Wave Ratio) of your antenna system to be sure it is properly matched for optimum performance and ensure that no excessive reflected RF power reaches the transmitter's output which can damage the output transistor. When shopping for a suitable model, ensure that the technical specifications indicate that it is capable of accurate measurement within the FM broadcast spectrum, 88~108 MHz.These meters sold in CB radio shops often are NOT capable of accurate measurement in the VHF spectrum, the FM broadcast band.
If I can be of further assistance, feel free to ask ! I am always more than happy to lend assistance to a community member !
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 Mar 22, 2018 3:16:31 GMT -6
Good Morning Tester !
I also wanted to bring to your attention this same exact FM broadcast transmitter marketed by CZE-RF (CZERF), the same company that manufactures the CZE-05B transmitter as well as numerous others. From my observation and research, this company seems to be the 'mother' of the Chinese manufactured FM broadcast transmitters that originally produces them. You will find just about, if not all of their products re-branded by a host of others including FMUser, NioRFNio, Sainsonic, HLLY and Signstek and possibly others I am not yet aware of, being sold on EBay.
From the pricing I have seen on EBay, you often can buy, basically the same exact transmitter with a simple makeover, cheaper, if you purchase the 'CZE' brand name unit or a 'generic' equivalent instead of the one equivalent model marketed by FMUser. FMUser prices are typically somewhat higher for the EXACT same unit ! In fact, the entire lineup of Chinese manufactured FM broadcast transmitters consists of only several 'base models' and only vary internally based on the rated RF output. The manufacturer simply utilizes a different RF output MOSFET, e.g., the CZE Model ST-05B utilizes a Mitsubishi RD05HVF1 power mosfet as the final amplifier device whereas the CZE-15A simply utilizes a Mitsubishi RD15HVF1 power mosfet as the final amplifier ! It's merely an enhanced version that utilizes the EXACT same main circuit board ! You will find this to be very common throughout mostly all of the different 'makes' and models of Chinese manufacture within this 'genre' of 'low' power FM broadcast transmitters. The 'hint' that is a dead giveaway confirming this, is in the layout and external component placement on the front panel of the transmitter.
The CZE Model CZE-15A is the EXACT same transmitter as the FMUser Model FU-15A and the 'generic' Model ST-15B. A generic ST-15B, of which I have two, can be purchased for $58.00 and FREE shipping on EBay. The FMUser clone of this costs $109.00 PLUS shipping on their website: So, with this information in mind, it really pays to shop around on Ebay and elsewhere before purchasing a particular transmitter as you can save a substantial amount of money by choosing wisely ! This EBay ad is truely outright laughable, see here, the "RangeStud" 15 watt FM transmitter:www.ebay.com/itm/RangeStud-15-W-FM-TRANSMITTER-RangeMax-1-0-Bundle/120653292204?hash=item1c177f22ac:g:TjEAAOSwFNZWwirf ...
This is the EXACT same transmitter as the CZE-15B, the FMUser Model FU-15A and the 'Generic' Model ST-15B ! As you can see all they did was throw in some crappy, cheap coaxial cable and an equally cheap, inferior, crappy antenna and boosted the 'package' price to $329.95 ! Quite a price like over the generic ST-15B at $58.00 !! SAME EXACT transmitter ! Well, anyway, you get the idea ! LOL !
I have included images of the circuit board used in the HLLY Model TX-10S to demonstrate it's fine craftsmanship as well as the Generic ST-15B and FMUser Model FU-15A circuit boards, you can clearly see the similarity ! LOL !! (Same Exact Transmitter). Well, I must get ready to leave for work. I'll review any messages here later today. Have a great day !
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"
I think I could underpower that circuit and it would be a buffer to bring the FM30b up to half watt so the amp can get the power it needs. I gotta get an output filter though, I don't want to potentially screw up the nearby airport.
Post by HighMountainRadio on Mar 22, 2018 16:49:29 GMT -6
Greetings Tester !
Actually I found several pretty simple low power RF amplifier circuits that would fill the need for you ! I will send you a few pix of the circuits in a short while. And, yes, your assumption about keeping the drive lower to provide the correct amount of drive to the 6 watt amp is correct ! By the way, I really admire your determination to learn about FM broadcast techniques and the gear required ! It's quite easy to become merely an 'appliance operator' without any actual knowledge of how it all works but to take the time required to actually educate yourself is to be commended !
Personally I tremendously enjoy salvaging and repurposing items and building as much as I possibly can since I derive a great amount of personal satisfaction in hearing my station's ass-kicking signal 20 miles away with crystal clear clarity and quality and knowing I was able to accomplish it and make sense of the 'voodoo' involved ! LOL ! Additionally, the added fringe benefit is the fact that you can save a substantial amount of money in the process !
"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"
It looks like that might be useful for a circuit that ups my power... a quick forum search says that Kage has done some work with the chip before, but all of his schematics images were not functioning, if anyone has the images, it would be much appreciated. Thanks again all!
Post by HighMountainRadio on Mar 23, 2018 2:18:50 GMT -6
Good Morning Tester !
Wow ! That's pretty bizarre how the link I sent you is now a dead link, it worked fine yesterday ! Try this link, it should work: www.next.gr/rf/amplifiers/FM-Linear-Amplifier-400mW-l60684.html Go figure !? Oh well, while I was on that site, I had the presence of mind to snag a LOT of various transmitter designs and most documentation, whatever was found with the schematic at least. I have included three designs here that are closest to the theme at hand. I have been pretty busy here the last couple of days since the furnace crapped out and I have to have a new one installed today, too many failed items to even consider patching it up. After I get out of work at 10 AM today I have to come right home and assist the installing plumber with the furnace swapout. Also the damn flue in the chimney partially collapsed so must use a power vent instead, all-in-all, $4000.00. Ouch !!
Check out these schematics and I'll check back with you later today after the furnace festivities.
The 2SC2314 maximum operating frequency is 250 MHz so at a quick glance it seems suitable for 88-108 MHz use. I've included a test circuit diagram for the 2SC2314 as well.
P.S. It looks like this thread stirred quite an interest ! As of this morning 373 views ! Cool !
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"
Thanks for the tasty links, I'm going to look into this. Should I be using the solid copper PCBs, then cutting solder pads with an exacto? I was looking at buying inductors, it seems like there is too much margin for error when winding your self, and I don't think I have the gear to measure Henrys. If anyone here has tricks for making good inductors, let me know.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I have heard of low pass filters, but there is a lot of variety out there, can you recommend anything specific? also, I have a pile of transistors, do you know offhand which ones are best for my situation? I might be able to dig it out of the box and add it to the Ramsey.
