Elecraft › [HAM]

Noise sources

Classic

List

Threaded

14 messages Options

kevinr@coho.net

Noise sources

For those of you interested in tracking down sources of household RF
noise here is an article describing one source you may not have
considered: cellular telephone chargers. Modern cell phones have become
thinner and thinner and are commonly recharged via a USB connection. A
comprehensive article in EE Times is available here:

www.eetimes.com/4230239

73,
Kevin. KD5ONS
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Bob K6UJ

Re: Noise sources

Thanks Kevin
I checked my families cell phone chargers and I'm OK (for now.)
It never ends. I periodically shut off the main breaker to our house and listen on HF with battery power to see if there are any new RFI culprits. My kids are
always using some new electronic gadget. I just discovered
that my Seagate Free Agent Pro external hard drive is radiating RFI like crazy.
I can pick up its radiation from my HF rig in the car parked in front of the house ! I should call Seagate
and inform them that they need to apply for an FCC license and get a call sign for my hard drive. hihi.

73,
Bob
K6UJ

On Jan 2, 2012, at 1:08 PM, kevinr wrote:

> For those of you interested in tracking down sources of household RF
> noise here is an article describing one source you may not have
> considered: cellular telephone chargers. Modern cell phones have become
> thinner and thinner and are commonly recharged via a USB connection. A
> comprehensive article in EE Times is available here:
>
> www.eetimes.com/4230239
>
> 73,
> Kevin. KD5ONS
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Richard Fjeld

Noise sources

In reply to this post by kevinr@coho.net

I saw a post about finding sources of noise, and I would like to share one that surprised me. The other night, I had 20/s9 noise on 75 meters all across the band. I got out my portable AM radio and was trying to find the cause when I heard a click and the noise was gone. I knew something had been turned off, so I went upstairs and asked my wife. She had just turned off the 'puck' light that is under the kitchen cabinet. When I turned it back on, there was no doubt!

It is simply a 12V incandescent bulb. Apparently the small metal box in-line on the power cord is a switching PS instead of a step-down transformer.

Richard Fjeld, n0ce
[hidden email]
E=IR, it's the law.
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Jim Brown-10

Re: Noise sources

On 1/2/2012 8:23 PM, Richard Fjeld wrote:
> It is simply a 12V incandescent bulb. Apparently the small metal box in-line on the power cord is a switching PS instead of a step-down transformer.

YES. This is a VERY common noise source, and finding a step-down
transformer for products like this can be quite difficult. The problem
is that while 12VAC will run the device just fine, the available
mounting space is just large enough for a switching power supply, and
far too small for a transformer. If you go to an electrical supply store
to buy one, they will sell you an unmarked box with wires coming out
that they call an "electronic transformer." What's inside is a very
noisy switching power supply. MAYBE it will have a UL label, indicating
safety agency compliance. and MAYBE that will be real, but UL standards
say NOTHING about EMC.

I'm told that it is possible to buy clean power supplies for low voltage
lighting, but I've never managed to do so.

73, Jim K9YC
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

John Gibson

OT: Quiet 12V-to-5V converter

Dear Elecraft list members,

The recent thread on noisy switching power supplies leads me to a related question. My son n8fyk, who teaches radio astronomy, has set up a project with his students. They are using a 15m direct-conversion Radio Jove receiver in the field to monitor radio emissions from Jupiter, the sun, and the galaxy. The receiver operates from 12V, which is readily supplied by a portable utility 12V battery pack. Their problem is powering their data recorder, which needs about 5V at 0.7A.

The data recorder is designed to operate from three internal AA alkaline cells, but these give a limited run time. My son would like to be able to leave the receiver and recorder for unattended operation for several days at a time.

One solution would be to use a 12V-to-5V power converter between the 12V battery and the data recorder. For long battery life, it would be nice to have the efficiency of a switching converter. Such a converter would have to be RF-quiet, so as not to interfere with their weak-signal reception.

I will be interested to hear what list members recommend.

Thank you and 73,

John, no8v
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Jeff Cochrane - VK4XA

Re: OT: Quiet 12V-to-5V converter

CONTENTS DELETED

The author has deleted this message.

Jack Smith-6

Re: OT: Quiet 12V-to-5V converter

In reply to this post by John Gibson

There are quite a few simple switching regulator chips for 12V --> 5V,
requiring only a handful of parts to make a complete switching
converter. For example, National Semiconductor (now TI after the recent
purchase) LM2591HVT-5.0/NOPB. Stocked by Mouser and DigiKey at about $6.
This series is available in a through hole 4-pin TO-220 style device so
breadboarding up a one-off power supply isn't too difficult.

With careful attention to detail, bypassing and shielding it should be
possible to build a quiet 5V, 1A supply around these parts. It can be
small enough to fit into a 2"x2"x1" Hammond die cast enclosure, and you
can use feedthrough caps for input and output, along with some internal
LC filtering.

Still, 5V at 700 mA with a switching regulator and a 12V battery
(assuming 100% efficiency which isn't possible of course) the setup will
require 300mA from the battery. For 100 hours of operation, you're
looking at a 30 Ah battery requirement. While a battery will output more
Ah with a 100 hour discharge cycle, it's not that much more. A 35Ah
sealed 12V gel-cel type lead acid battery will run you about $100.

For serious long duration battery operation, I would look for a more
thrifty data logger.

Jack K8ZOA

On 1/6/2012 10:10 AM, John Gibson wrote:

> Dear Elecraft list members,
>
> The recent thread on noisy switching power supplies leads me to a related question. My son n8fyk, who teaches radio astronomy, has set up a project with his students. They are using a 15m direct-conversion Radio Jove receiver in the field to monitor radio emissions from Jupiter, the sun, and the galaxy. The receiver operates from 12V, which is readily supplied by a portable utility 12V battery pack. Their problem is powering their data recorder, which needs about 5V at 0.7A.
>
> The data recorder is designed to operate from three internal AA alkaline cells, but these give a limited run time. My son would like to be able to leave the receiver and recorder for unattended operation for several days at a time.
>
> One solution would be to use a 12V-to-5V power converter between the 12V battery and the data recorder. For long battery life, it would be nice to have the efficiency of a switching converter. Such a converter would have to be RF-quiet, so as not to interfere with their weak-signal reception.
>
> I will be interested to hear what list members recommend.
>
> Thank you and 73,
>
> John, no8v
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

David Gilbert

Re: OT: Quiet 12V-to-5V converter

Why not just use a 6 volt motorcycle battery (two or three in parallel
if necessary) with a series diode? The total weight isn't going to be
any different no matter what you do ... one battery for everything or
separate batteries for receiver and data logging. AH capacity is AH
capacity. The efficiency would probably be above 85% if a diode rated
for a couple of amps was used, assuming a Vf around 0.7 volts, and it
would be tough to beat for quiet.

Dave AB7E

On 1/6/2012 9:34 AM, Jack Smith wrote:

> There are quite a few simple switching regulator chips for 12V --> 5V,
> requiring only a handful of parts to make a complete switching
> converter. For example, National Semiconductor (now TI after the recent
> purchase) LM2591HVT-5.0/NOPB. Stocked by Mouser and DigiKey at about $6.
> This series is available in a through hole 4-pin TO-220 style device so
> breadboarding up a one-off power supply isn't too difficult.
>
> With careful attention to detail, bypassing and shielding it should be
> possible to build a quiet 5V, 1A supply around these parts. It can be
> small enough to fit into a 2"x2"x1" Hammond die cast enclosure, and you
> can use feedthrough caps for input and output, along with some internal
> LC filtering.
>
> Still, 5V at 700 mA with a switching regulator and a 12V battery
> (assuming 100% efficiency which isn't possible of course) the setup will
> require 300mA from the battery. For 100 hours of operation, you're
> looking at a 30 Ah battery requirement. While a battery will output more
> Ah with a 100 hour discharge cycle, it's not that much more. A 35Ah
> sealed 12V gel-cel type lead acid battery will run you about $100.
>
> For serious long duration battery operation, I would look for a more
> thrifty data logger.
>
> Jack K8ZOA
>
>
> On 1/6/2012 10:10 AM, John Gibson wrote:
>> Dear Elecraft list members,
>>
>> The recent thread on noisy switching power supplies leads me to a related question. My son n8fyk, who teaches radio astronomy, has set up a project with his students. They are using a 15m direct-conversion Radio Jove receiver in the field to monitor radio emissions from Jupiter, the sun, and the galaxy. The receiver operates from 12V, which is readily supplied by a portable utility 12V battery pack. Their problem is powering their data recorder, which needs about 5V at 0.7A.
>>
>> The data recorder is designed to operate from three internal AA alkaline cells, but these give a limited run time. My son would like to be able to leave the receiver and recorder for unattended operation for several days at a time.
>>
>> One solution would be to use a 12V-to-5V power converter between the 12V battery and the data recorder. For long battery life, it would be nice to have the efficiency of a switching converter. Such a converter would have to be RF-quiet, so as not to interfere with their weak-signal reception.
>>
>> I will be interested to hear what list members recommend.
>>
>> Thank you and 73,
>>
>> John, no8v

Jack Smith-6

Re: OT: Quiet 12V-to-5V converter

While a 6V battery may work, I would be concerned with voltage
regulation. If the data logger is a true 5V device, a simple series
diode may not keep the supply within acceptable limits over the typical
range of battery voltage from full charge to discharge. An analog LDO
regulator would be a better choice than a diode.

However, a 12V battery supply would, according to the original post,
also allow the receiver to be powered from one source.

Jack K8ZOA

On 1/6/2012 12:49 PM, David Gilbert wrote:

>
> Why not just use a 6 volt motorcycle battery (two or three in parallel
> if necessary) with a series diode? The total weight isn't going to be
> any different no matter what you do ... one battery for everything or
> separate batteries for receiver and data logging. AH capacity is AH
> capacity. The efficiency would probably be above 85% if a diode rated
> for a couple of amps was used, assuming a Vf around 0.7 volts, and it
> would be tough to beat for quiet.
>
> Dave AB7E
>
>
>
> On 1/6/2012 9:34 AM, Jack Smith wrote:
>> There are quite a few simple switching regulator chips for 12V --> 5V,
>> requiring only a handful of parts to make a complete switching
>> converter. For example, National Semiconductor (now TI after the recent
>> purchase) LM2591HVT-5.0/NOPB. Stocked by Mouser and DigiKey at about $6.
>> This series is available in a through hole 4-pin TO-220 style device so
>> breadboarding up a one-off power supply isn't too difficult.
>>
>> With careful attention to detail, bypassing and shielding it should be
>> possible to build a quiet 5V, 1A supply around these parts. It can be
>> small enough to fit into a 2"x2"x1" Hammond die cast enclosure, and you
>> can use feedthrough caps for input and output, along with some internal
>> LC filtering.
>>
>> Still, 5V at 700 mA with a switching regulator and a 12V battery
>> (assuming 100% efficiency which isn't possible of course) the setup will
>> require 300mA from the battery. For 100 hours of operation, you're
>> looking at a 30 Ah battery requirement. While a battery will output more
>> Ah with a 100 hour discharge cycle, it's not that much more. A 35Ah
>> sealed 12V gel-cel type lead acid battery will run you about $100.
>>
>> For serious long duration battery operation, I would look for a more
>> thrifty data logger.
>>
>> Jack K8ZOA
>>
>>
>> On 1/6/2012 10:10 AM, John Gibson wrote:
>>> Dear Elecraft list members,
>>>
>>> The recent thread on noisy switching power supplies leads me to a related question. My son n8fyk, who teaches radio astronomy, has set up a project with his students. They are using a 15m direct-conversion Radio Jove receiver in the field to monitor radio emissions from Jupiter, the sun, and the galaxy. The receiver operates from 12V, which is readily supplied by a portable utility 12V battery pack. Their problem is powering their data recorder, which needs about 5V at 0.7A.
>>>
>>> The data recorder is designed to operate from three internal AA alkaline cells, but these give a limited run time. My son would like to be able to leave the receiver and recorder for unattended operation for several days at a time.
>>>
>>> One solution would be to use a 12V-to-5V power converter between the 12V battery and the data recorder. For long battery life, it would be nice to have the efficiency of a switching converter. Such a converter would have to be RF-quiet, so as not to interfere with their weak-signal reception.
>>>
>>> I will be interested to hear what list members recommend.
>>>
>>> Thank you and 73,
>>>
>>> John, no8v
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

KXBill

Re: Motorcycle Battery??

John/NO8V
Mention "Motorcycle" and the price raises accordingly. However, the site below lists various non-motorcycle sealed batteries at (IMHO) a reasonable price.Don't know what A/h your looking for; those below are for 7 A/hr.
6v= http://www.atbatt.com/sealed-lead-acid-batteries/b/universal-power-group/m/d5734.asp
12v= http://www.atbatt.com/sealed-lead-acid-batteries/b/universal-power-group/m/45566.asp
Good luck on your quest.,
Bill-w7kxb

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

John Gibson

Re: OT: Quiet 12V-to-5V converter

In reply to this post by Jack Smith-6

Thanks to all who responded to my query. At this point I plan to follow Jack Smith's excellent recommendation to build a DC-to-DC converter based on the LM-2591 chip and do my best with appropriate filtering to keep RFI from getting out of the box.

I appreciate having the excellent resources of the Elecraft reflector to draw upon for solving this type of problem.

73,
John, no8v
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

David Gilbert

Re: OT: Quiet 12V-to-5V converter

In reply to this post by Jack Smith-6

Well, he said that the data recorder was designed for and currently uses
three AA alkaline batteries. Those things have far from a flat
discharge voltage curve so I assumed that the data recorder had some
sort of internal regulation.

I also assumed he would have to add another battery anyway since not
many utility packs have anything close to the capacity it would require
to deliver 0.7 amps for "several days". Five days times 24 hours per
day times 0.7 amps is about 80AH, and you still have to derate that for
the practical discharge threshold of a normal battery. We're talking
well over 100 AH, and I'll bet that the utility power pack they're using
has less than a tenth of that. Maybe it is important to run everything
off one battery, but if so I'll bet it won't be the one they already have.

Dave AB7E

On 1/6/2012 1:07 PM, Jack Smith wrote:

> While a 6V battery may work, I would be concerned with voltage
> regulation. If the data logger is a true 5V device, a simple series
> diode may not keep the supply within acceptable limits over the typical
> range of battery voltage from full charge to discharge. An analog LDO
> regulator would be a better choice than a diode.
>
> However, a 12V battery supply would, according to the original post,
> also allow the receiver to be powered from one source.
>
> Jack K8ZOA
>
>
> On 1/6/2012 12:49 PM, David Gilbert wrote:
>> Why not just use a 6 volt motorcycle battery (two or three in parallel
>> if necessary) with a series diode? The total weight isn't going to be
>> any different no matter what you do ... one battery for everything or
>> separate batteries for receiver and data logging. AH capacity is AH
>> capacity. The efficiency would probably be above 85% if a diode rated
>> for a couple of amps was used, assuming a Vf around 0.7 volts, and it
>> would be tough to beat for quiet.
>>
>> Dave AB7E
>>
>>
>>
>> On 1/6/2012 9:34 AM, Jack Smith wrote:
>>> There are quite a few simple switching regulator chips for 12V --> 5V,
>>> requiring only a handful of parts to make a complete switching
>>> converter. For example, National Semiconductor (now TI after the recent
>>> purchase) LM2591HVT-5.0/NOPB. Stocked by Mouser and DigiKey at about $6.
>>> This series is available in a through hole 4-pin TO-220 style device so
>>> breadboarding up a one-off power supply isn't too difficult.
>>>
>>> With careful attention to detail, bypassing and shielding it should be
>>> possible to build a quiet 5V, 1A supply around these parts. It can be
>>> small enough to fit into a 2"x2"x1" Hammond die cast enclosure, and you
>>> can use feedthrough caps for input and output, along with some internal
>>> LC filtering.
>>>
>>> Still, 5V at 700 mA with a switching regulator and a 12V battery
>>> (assuming 100% efficiency which isn't possible of course) the setup will
>>> require 300mA from the battery. For 100 hours of operation, you're
>>> looking at a 30 Ah battery requirement. While a battery will output more
>>> Ah with a 100 hour discharge cycle, it's not that much more. A 35Ah
>>> sealed 12V gel-cel type lead acid battery will run you about $100.
>>>
>>> For serious long duration battery operation, I would look for a more
>>> thrifty data logger.
>>>
>>> Jack K8ZOA
>>>
>>>
>>> On 1/6/2012 10:10 AM, John Gibson wrote:
>>>> Dear Elecraft list members,
>>>>
>>>> The recent thread on noisy switching power supplies leads me to a related question. My son n8fyk, who teaches radio astronomy, has set up a project with his students. They are using a 15m direct-conversion Radio Jove receiver in the field to monitor radio emissions from Jupiter, the sun, and the galaxy. The receiver operates from 12V, which is readily supplied by a portable utility 12V battery pack. Their problem is powering their data recorder, which needs about 5V at 0.7A.
>>>>
>>>> The data recorder is designed to operate from three internal AA alkaline cells, but these give a limited run time. My son would like to be able to leave the receiver and recorder for unattended operation for several days at a time.
>>>>
>>>> One solution would be to use a 12V-to-5V power converter between the 12V battery and the data recorder. For long battery life, it would be nice to have the efficiency of a switching converter. Such a converter would have to be RF-quiet, so as not to interfere with their weak-signal reception.
>>>>
>>>> I will be interested to hear what list members recommend.
>>>>
>>>> Thank you and 73,
>>>>
>>>> John, no8v
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

Fred Townsend

Re: OT: Quiet 12V-to-5V converter

In reply to this post by John Gibson

Hi John:
OK let's say your requirement is for a low noise, high efficiency converter
delivering 4.5 to 5V at up to 1 amp. There are hundreds of series linear
regulators that will do that job but the will dissipate more than 3 watts as
heat and that will require a small heatsink. For greater efficiency you will
want a switching regulator.
Fortunately there are also hundreds of switching regulators available too.
Many of the manufactures have online software for designing the circuit.
What you want is a low RFI design. There are various categories of RFI.
Your receiver should already be protected against conducted RFI so you
should be protecting your receiver against radiated RFI.
Radiated RFI comes from either magnet or electric fields. Of the two types,
electric fields are much easier to shield or reduce. Again, this translates
to a switching regulator that stores energy in capacitors rather than
inductors. For maximum efficiency the circuit should use two FETs (one for
switching and one for commutating). Searching the manufacture's web pages
for Low RFI switching regulators will usually find what you need. Then when
you have a working circuit, enclose it in a metal box to provide an
effective Faraday shield. The same manufacturer pages will also provide you
with app notes that will also provide a typical design.

Finally keep your regulator as far away as possible from your receiver. DO
NOT put them in the same box.
Hope this helps.
73
Fred, AE6QL
-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of John Gibson
Sent: Friday, January 06, 2012 7:11 AM
To: [hidden email]
Subject: [Elecraft] OT: Quiet 12V-to-5V converter

Dear Elecraft list members,

The recent thread on noisy switching power supplies leads me to a related
question. My son n8fyk, who teaches radio astronomy, has set up a project
with his students. They are using a 15m direct-conversion Radio Jove
receiver in the field to monitor radio emissions from Jupiter, the sun, and
the galaxy. The receiver operates from 12V, which is readily supplied by a
portable utility 12V battery pack. Their problem is powering their data
recorder, which needs about 5V at 0.7A.

The data recorder is designed to operate from three internal AA alkaline
cells, but these give a limited run time. My son would like to be able to
leave the receiver and recorder for unattended operation for several days at
a time.

One solution would be to use a 12V-to-5V power converter between the 12V
battery and the data recorder. For long battery life, it would be nice to
have the efficiency of a switching converter. Such a converter would have to
be RF-quiet, so as not to interfere with their weak-signal reception.

I will be interested to hear what list members recommend.

Thank you and 73,

John, no8v
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

John Gibson

Re: OT: Quiet 12V-to-5V converter

In reply to this post by John Gibson

Thanks, Fred. The LMZ12001 does look attractive. The best solution may be for me to buy their LMZ12001EVAL/NOPB evaluation board.

See http://www.national.com/pf/LM/LMZ12001.html#Boards

I will, of course, add appropriate input and output filtering.

73,
John, no8v
-----
From: Fred Townsend <[hidden email]>
Subject: RE: [Elecraft] OT: Quiet 12V-to-5V converter

If you are going for the 2591 take a look at the LMZ12001. Fewer parts, lower RFI.
-----
From: [hidden email]
Subject: Re: [Elecraft] OT: Quiet 12V-to-5V converter

Thanks to all who responded to my query. At this point I plan to follow Jack Smith's excellent recommendation to build a DC-to-DC converter based on
the LM-2591 chip and do my best with appropriate filtering to keep RFI from getting out of the box.

73,
John, no8v
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html