[ARC5] [Milsurplus] Sandy Coolness for Our BAs
Scott Johnson
scottjohnson1 at cox.net
Sat May 13 11:04:57 EDT 2017
Scott-
I would respectfully reply that you look at some of the more resent SMPS
offerings with respect to noise. I have successfully powered many receiver
and amplifier project with SMPS, and have had little to no noise issue, even
on 160M. I look at many of these with my HP 8566B spectrum analyzer, and
many of them barely raise the noise floor. The level of refinement in SMPS
design over the last ten years is truly amazing.
Scott V. Johnson W7SVJ
Sunburst Engineering
5111 E. Sharon Dr.
Scottsdale, AZ 85254-3636
H (602) 953-5779
C (480) 550-2358
scottjohnson1 at cox.net
scott.johnson at ieee.org
-----Original Message-----
From: ARC5 [mailto:arc5-bounces at mailman.qth.net] On Behalf Of Scott Robinson
Sent: Saturday, May 13, 2017 6:54 AM
To: J Mcvey <ac2eu at yahoo.com>; Tom Lee <tomlee at ee.stanford.edu>;
arc5 at mailman.qth.net
Subject: Re: [ARC5] [Milsurplus] Sandy Coolness for Our BAs
Folks,
I don't think putting ANY switch mode power supply in a radio is a good
idea. It will have to be *very* carefully shielded and its inputs and
outputs filtered to avoid radiating strong RF signals inside the radio.
These things have very fast edges whose harmonics go on well up into many
megahertz.
Peace,
Scott
On 5/13/17 6:35 AM, J Mcvey via ARC5 wrote:
> Rather than an additional analog power supply, how about a SMPS or one
> of those small flyback type regulators that can make 12 0r 24 V into
> 135V or 250V or whatever you design it to do?
> Tom Hanz had the "replacement armature " concept that replaced the
> rotating armature in the dyno with a smps board that made contact with
> the brushes. A Very cool idea to keep the original look.
> I had considered building a flyback supply inside a small box with
> bananna jacks to inerface with the radio .
> These have OC and OV shudowns and WILL survive a screwdriver !
>
>
> On Saturday, May 13, 2017 2:40 AM, Tom Lee <tomlee at ee.stanford.edu> wrote:
>
>
> The ones I've encountered in the past were very good at exploding
> during an unscheduled screwdriver test, so Dennis has an excellent
> point. These are very simple regulators, so their short-circuit
> protection consists of instructions to the user not to short it.
>
> --Cheers,
> Tom
>
> --
> Prof. Thomas H. Lee
> Allen Bldg., CIS-205
> 420 Via Palou Mall
> Stanford University
> Stanford, CA 94305-4070
> http://www-smirc.stanford.edu <http://www-smirc.stanford.edu/>
> 650-725-3383 (public fax; no confidential information, please)
>
> On 5/12/2017 11:25 PM, Dennis Monticelli wrote:
>> The one transistor NPN control device probably just has a zener
>> between its emitter and ground. A resistor divider across the output
>> has its tap connected to the base of that NPN.
>>
>> I don't know what the SOA of that Darlington is or if there is
>> another NPN in there serving as a current limit. In other words it
>> may not survive a screwdriver short so beware.
>>
>> Dennis AE6C
>>
>> On Fri, May 12, 2017 at 10:15 PM, David Stinson <arc5 at ix.netcom.com
>> <mailto:arc5 at ix.netcom.com>> wrote:
>>
>> ----- Original Message ----- From: "Tom Lee"
>> <tomlee at ee.stanford.edu <mailto:tomlee at ee.stanford.edu>>
>> Subject: Re: [ARC5] [Milsurplus] Sandy Coolness for Our BAs
>>
>> If this part is like some of the TV regulators I've
>> encountered in the
>> past, the base terminal needs to be pulled up to the
>> unregulated input
>> voltage through a resistor. Depending on the input-output
>> differential
>> you seek, the resistor will be of the order of 10k or so,
>> typically.
>> Frequency compensation is also frequently required, and the base
>> terminal is a convenient place to connect an appropriate
>> stabilization
>> network (e.g., C or series RC to ground).
>>
>>
>> Mr. Tom Lee was exactly correct.
>> Many thanks also to Bob AH7I, and
>> John Kidd from Australia for more info
>> and details.
>> 10 K from INPUT to BIAS, .1 uFd
>> from BIAS to COMMON and 10 uFd on
>> the OUTPUT, similar to what one would do
>> with a common low-V regulator.
>> The isolation transformer, bridge and
>> 47 mFd filter is supplying ripply 180V
>> peak to the regulator device.
>> A nice, clean and steady 135V is
>> running the receiver.
>>
>> Gentlemen like you continue to prove
>> that my confidence in our community
>> is well-founded.
>>
>> TNX OM ES 73 DE Dave AB5S
>>
>>
>>
>> ----- Original Message ----- From: "Tom Lee"
>> <tomlee at ee.stanford.edu <mailto:tomlee at ee.stanford.edu>>
>> Subject: Re: [ARC5] [Milsurplus] Sandy Coolness for Our BAs
>>
>>
>> If this part is like some of the TV regulators I've
>> encountered in the
>> past, the base terminal needs to be pulled up to the
>> unregulated input
>> voltage through a resistor. Depending on the input-output
>> differential
>> you seek, the resistor will be of the order of 10k or so,
>> typically.
>> Frequency compensation is also frequently required, and the base
>> terminal is a convenient place to connect an appropriate
>> stabilization
>> network (e.g., C or series RC to ground).
>>
>>
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