Power Supply for a FM-02

[RobertB]

Ok,
Pretty new to the forum. I have been looking through the forums and notice that many folks are using some "quite" supplies for their Vast FM-02. I originally was going to use a wallwart and a ferite choke. I see now it may be noisy. I also have a couple of laptop power supplies. Has anyone tried these? Being a ham radio op, I also have several power supplies. One is a switching one and not sure if it will be noisy or not (Rat Shack 25, 30amp job?). Have a 35amp Astron, but that is really overkill I think. I have seen several people mention that it must be at 12v. Soooo, it won't like 13.8v that most of the supplies put out? Have to look at the laptop supplies to see what it is rated at.

Just wasn't sure if anyone has tried any of the above with success or not. Don't want to blow it up.

I am at work right now, and know my transmitter is sitting on my desk right now...just waiting for me. Want to play when I get home!!!
:-)
Robert
KD4YDC

[ukewarrior]

I use a wall wart listed as 12v. this of course puts out something more like 15.5V without a load.
That feeds an inexpensive voltage regulator to guarantee a nice steady 12v DC power. (Sure electronics < $5)
I put a nice big ferrite bead around the power between the wall wart and the regulator. (I also put a wee tiny one between the regulator and the transmitter.)
Without the ferrite beads, there would be a noticeable hum.

The FM02 uses less them 100ma of power. So, you can go with something very, very small to drive it.

[RobertB]

I use a wall wart listed as 12v. this of course puts out something more like 15.5V without a load.
That feeds an inexpensive voltage regulator to guarantee a nice steady 12v DC power. (Sure electronics < $5)
I put a nice big ferrite bead around the power between the wall wart and the regulator. (I also put a wee tiny one between the regulator and the transmitter.)
Without the ferrite beads, there would be a noticeable hum.

The FM02 uses less them 100ma of power. So, you can go with something very, very small to drive it.

I guess my bigger question is, I guess the FM-02 cannot be driven above 12v? I honestly have several power supplies around the house that I could use if it could be driven at 13.8v.

In doing research today I saw the little regulator you speak of. Cute. I am just afraid with Halloween around...it won't be here in time for me to experiment with. I did find this;
http://www.hidplanet.com/forums/showthread.php?25070-DIY-12v-Regulator
Have built several like this for some "handi talkies" that need to be dropped from 12v down to 7.2v. (obviously not what I need here). I might even have the right regulator laying around the house. Just have to dig into my junk box.

May just throw it into my show computer, but honestly would like to separate it out.

[ags0000]

I use a wall wart listed as 12v. this of course puts out something more like 15.5V without a load.
That feeds an inexpensive voltage regulator to guarantee a nice steady 12v DC power. (Sure electronics < $5)
I put a nice big ferrite bead around the power between the wall wart and the regulator. (I also put a wee tiny one between the regulator and the transmitter.)
Without the ferrite beads, there would be a noticeable hum.

The FM02 uses less them 100ma of power. So, you can go with something very, very small to drive it.

I built the W3 and found that with some wall-warts, a hum is still present. I haven't figured out why or how. To get past it, I'd like to use the ferrite beads you recommend and see if that works to suppress the hum. I'll be placing a FutureElectronics order imminently and would like to throw those in the order as well.

Would you kindly put some quantitative value on nice "big" and "wee tiny" for those without practical knowledge on this topic?

Thanks.

[IdunBenhad]

Hi:
Yes, the FM02 can be supplied with 13.5 vdc. That is well within it's rating. I think the upper voltage limit is 15 or 16 vdc.

The FM02 has been operated successfully with as little as 6 vdc. It drops out of frequency lock around that voltage. Of course, the power output is down, but it still works.

If you are interested in using an AC wall wart, look up the W3 (Wall Wart Wizard) power supply. It is listed under the forum "Radio Waves". Also, the "Very Quiet Supply".

Some laptop power supplies can be very noisy and put high frequencies into the audio of the FM02, causing it to appear not to function correctly (this happened to me). Be very careful of the audio level going into the TX, it can be overdriven very easily.

[ukewarrior]

If you look at the tech that is already in your house, you will see these beads on lots of things. They are in power cords, and even ethernet cables. I get mine for free this way. I just cut them out of these cords.
If you work in an office, you can usually go to the cube of the LAN/Networking guys and ask them for an excess power cord with one of these 'bumps' in the cord. They usually have dozens of extras laying around.

As far as size, you want to be able to wrap the wire through the hole and around the perimeter 3 times for maximum effect. You also need to wrap it tightly and secure it in place with a nylon tie wrap. So, it depends on the size of the wire that comes out of your wall wart, you need to have a diameter that can fit three wraps of the wire and the tie.
Do this picture three times: (some of these split in half, some don't !)
http://www.quantumbalancing.com/images/cp04.jpg
http://www.doityourselfchristmas.com/wiki/index.php?title=File:Ferrite_2.jpg

There are some good pictures in the wiki-pedia-:
http://en.wikipedia.org/wiki/Ferrite_bead


I built the W3 and found that with some wall-warts, a hum is still present. I haven't figured out why or how. To get past it, I'd like to use the ferrite beads you recommend and see if that works to suppress the hum. I'll be placing a FutureElectronics order imminently and would like to throw those in the order as well.

Would you kindly put some quantitative value on nice "big" and "wee tiny" for those without practical knowledge on this topic?

Thanks.

[RobertB]

The info I exactly needed...THANKS!
Why reinvent the wheel. I have this small switching power supply (Radio Shack 25amp 13.8v) that is far as I can tell...clean at 88.7mhz. Haven't taken my monitor to it yet, but by my ear it is fine. Works like a champ on it.

Took a mfj analyzer and stripped off some rg58, threw some wire on either end, trimmed to 50 ohms...1.2swr. Taped it to the porch post and drove up and down the street. With houses and trees blocking the line of sight from the antenna...still worked up the street some 1000ft or so. Now to find a box for the transmitter and off we go. Love the little transmitter and good deal for the money.

BTW, I do see what you are saying about over driving it. Will have to play with that.

Thanks all!



Hi:
Yes, the FM02 can be supplied with 13.5 vdc. That is well within it's rating. I think the upper voltage limit is 15 or 16 vdc.

The FM02 has been operated successfully with as little as 6 vdc. It drops out of frequency lock around that voltage. Of course, the power output is down, but it still works.

If you are interested in using an AC wall wart, look up the W3 (Wall Wart Wizard) power supply. It is listed under the forum "Radio Waves". Also, the "Very Quiet Supply".

Some laptop power supplies can be very noisy and put high frequencies into the audio of the FM02, causing it to appear not to function correctly (this happened to me). Be very careful of the audio level going into the TX, it can be overdriven very easily.

[ukewarrior]

I would disagree with any recommendation to use more then 12v DC.

The folks from VAST have specifically stated to run no more then 12v.

Check out the wiki as the source for FM02 information !
http://www.doityourselfchristmas.com/wiki/index.php?title=Vastelec_FM02

[vastelec]

Re the V-FM02, The power avaliable from DC9V-16V. Pls use the low interference power adaptor, or increase capacitance and inductor.
when you connect with PC or audio Player device, You can connect with V-FM02 ground line. It will be better

[IdunBenhad]

Hi:
Even though the WIKI says no more than 12 vdc, I have not had any problems running at 12.5 vdc for 2 years. During the light season, the transmitter usually runs for at least 8 hours per day.

Using the W3 regulator, I usually set the voltage at 12.5 vdc, but as I stated, the FM02 will operate down to about 6 vdc before it drops out of lock.

My transmitter draws about 75 ma. @ 12.5 vdc.

Although I can't find it right now, I had read somewhere that the maximum upper limit was about 15 vdc and I had thought this was from the Vastelec website, but I can't find it.

Maybe Vastelec can clarify this rating.

It is my opinion and observation that the FM02 should have no problems at 13.5 vdc, including no overheating.

Having said all that, if the stated rating is 12 vdc, then we should probably be running at that voltage until we can get further clarification from Vastelec.

[ukewarrior]

I will ask VAST again about the voltage and post their reply.

Hi:
Even though the WIKI says no more than 12 vdc, I have not had any problems running at 12.5 vdc for 2 years. During the light season, the transmitter usually runs for at least 8 hours per day.

Using the W3 regulator, I usually set the voltage at 12.5 vdc, but as I stated, the FM02 will operate down to about 6 vdc before it drops out of lock.

My transmitter draws about 75 ma. @ 12.5 vdc.

Although I can't find it right now, I had read somewhere that the maximum upper limit was about 15 vdc and I had thought this was from the Vastelec website, but I can't find it.

Maybe Vastelec can clarify this rating.

It is my opinion and observation that the FM02 should have no problems at 13.5 vdc, including no overheating.

Having said all that, if the stated rating is 12 vdc, then we should probably be running at that voltage until we can get further clarification from Vastelec.

[ukewarrior]

Here is the OFFICIAL response, verbatim, from VAST regarding FM02 power:

FM02 appropriate voltage DC 9V-16V, The maximum voltage DC 16-24V, It will be hot for some parts and it easy broken.
When you connect the power, Pls make sure the power (anode +) and power(cathode –), It can not make wrong.


I have corrected the wiki to show this acceptable power range of 9V-16V DC.

[IdunBenhad]

Hi:
Thanks, UKEWARRIOR, for your efforts in getting an "official" statement from Vastelec.

Now we all know what the voltage rating is.

However, I don't think I would run the FM02 at anywhere near the upper rating of 24 vdc. It is good to have a nice safety factor, however.

Thanks again.

[Aurbo99]

I use the 12vdc output from an old ATX power supply, works fine. no hum.

[CaptKirk]

I use a 12v wall-wart from some expired piece of technology that is obviously a switching power supply, rather than a rectified transformer. You can tell because they tend to weigh less yet put out higher current than the transformer based power supplies. They are also better regulated at no to low current draw. I think the one I am using is from a dead network hub.