K-Line Addition - DC Power Supply (Suggestion)

[hhoyt]

Depending on cost, I'd bite, and it would be a nice addition to the K-line.  I have picked through several switchers, none of which were dead RF quiet.  I ended up defaulting to my Xantrex HPD 30-10 lab supply, which is a hybrid switching front-end/linear tracking output regulator.  It is dead RF quiet, but I am a bit scared to leave a supply that can output above 15 volts on my Elecraft.  I'd also like to free that supply back up for other uses.

Being linear regulators, the Astron supplies are probably pretty RF quiet, but for what they cost they are big and can be acoustically noisy (I have heard several buzzing transformers), not to mention containing antiquated circuitry.  LM723 regulators are not the quietest nor most stable linear reg ICs available these days, and have limited regulation bandwidth in stable implementations.  Considering these factors i have been reticent to buy one.

I bet Elecraft can outdo what is available in a pretty little matching package.

Howie - WA4PSC

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[Alan Bloom]

On Tue, 2012-09-18 at 14:14 -0700, Ron D'Eau Claire wrote:
...
> I'm not sure what you mean about the regulator not being "quiet". The LM723
> is a simple linear I.C.; no switching noise and no acoustical noise.
...

It's true that the 723 is a really ancient IC - it was designed back in
the 70's I believe.  It is also true that there are some pitfalls with
using it that can trap the unwary.  But with proper design it can be
made to work just fine.

Alan N1AL


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[Vic Rosenthal]

I've fixed two Astrons for friends. One had a burned-out IC and the
other had a damaged board where the capacitor mounting screws had
loosened and generated heat. Both failed without producing overvoltage.

I have one that I've been using for perhaps 15 years with no problems.

On 9/18/12 2:14 PM, Ron D'Eau Claire wrote:

> I guess it depends upon which Astron model you are working with. I've worked
> with a great many RS and RM Astron supplies in Ham and Commercial systems
> over the years and have never encountered one that made more than a very,
> very quiet hum.
>
> I'm not sure what you mean about the regulator not being "quiet". The LM723
> is a simple linear I.C.; no switching noise and no acoustical noise.
>
> The popular RS and RM series have both automatic over-voltage and
> over-current shut-down that protects both the power supply and any equipment
> connected to it.
>
> In decades of use working with a great number of Astron supplies - many of
> which are in 24/7 service operating commercial equipment - I've yet to see a
> regulator failure - or any Astron failure for that matter. I'm not
> suggesting that they won't fail, but I've yet to see it happen in,
> conservatively, tens of thousands of operating hours.
>
> My station Astron resides on a shelf out of the way under the operating
> table so having a matching appearance with the rest of the K-line is not an
> issue for me.
>
> 73, Ron AC7AC
>
>
>
> -----Original Message-----
>
>
> Being linear regulators, the Astron supplies are probably pretty RF quiet,
> but for what they cost they are big and can be acoustically noisy (I have
> heard several buzzing transformers), not to mention containing antiquated
> circuitry.  LM723 regulators are not the quietest nor most stable linear reg
> ICs available these days, and have limited regulation bandwidth in stable
> implementations.  Considering these factors i have been reticent to buy one.
>
> I bet Elecraft can outdo what is available in a pretty little matching
> package.
>
> Howie - WA4PSC

--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
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[ke9uw]

The Astron supplies usually have a crowbar on the output which shorts the output if the voltage rises above 15 Volts.

Sent from my iPad

On Sep 18, 2012, at 5:51 PM, "Vic, K2VCO" <[hidden email]> wrote:

> I've fixed two Astrons for friends. One had a burned-out IC and the
> other had a damaged board where the capacitor mounting screws had
> loosened and generated heat. Both failed without producing overvoltage.
>
> I have one that I've been using for perhaps 15 years with no problems.
>
> On 9/18/12 2:14 PM, Ron D'Eau Claire wrote:
>> I guess it depends upon which Astron model you are working with. I've worked
>> with a great many RS and RM Astron supplies in Ham and Commercial systems
>> over the years and have never encountered one that made more than a very,
>> very quiet hum.
>>
>> I'm not sure what you mean about the regulator not being "quiet". The LM723
>> is a simple linear I.C.; no switching noise and no acoustical noise.
>>
>> The popular RS and RM series have both automatic over-voltage and
>> over-current shut-down that protects both the power supply and any equipment
>> connected to it.
>>
>> In decades of use working with a great number of Astron supplies - many of
>> which are in 24/7 service operating commercial equipment - I've yet to see a
>> regulator failure - or any Astron failure for that matter. I'm not
>> suggesting that they won't fail, but I've yet to see it happen in,
>> conservatively, tens of thousands of operating hours.
>>
>> My station Astron resides on a shelf out of the way under the operating
>> table so having a matching appearance with the rest of the K-line is not an
>> issue for me.
>>
>> 73, Ron AC7AC
>>
>>
>>
>> -----Original Message-----
>>
>>
>> Being linear regulators, the Astron supplies are probably pretty RF quiet,
>> but for what they cost they are big and can be acoustically noisy (I have
>> heard several buzzing transformers), not to mention containing antiquated
>> circuitry.  LM723 regulators are not the quietest nor most stable linear reg
>> ICs available these days, and have limited regulation bandwidth in stable
>> implementations.  Considering these factors i have been reticent to buy one.
>>
>> I bet Elecraft can outdo what is available in a pretty little matching
>> package.
>>
>> Howie - WA4PSC
>
>
> --
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco/
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>
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> Please help support this email list: http://www.qsl.net/donate.html

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[Bill Frantz]

I must say I have a number of projects I would rather have
Elecraft engineering work on rather than built yet another power
supply. For example:

   #1: Direct digital computer I/O for the K3, eliminating all the
   A/D and D/A conversions now required between the DSP and the
   computer.

   #2: Full MacIntosh support for all utilities. [And Jim (W4ATK),
   I will try Crossover when I am up to bleeping with my computer
   instead of doing things like building a paddle so I can try to
   become CW competent. Thanks for your offer of assistance, I may
   be in touch some day.]


On 9/18/12 at 16:05, [hidden email] (hawley, charles j
jr) wrote:

If I need to replace the Icom supply I got at the electronics
flea market, the Astron supplies have gotten really good press
on this list.

Cheers - Bill, AE6JV

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[gm3sek]

Alan Bloom wrote:
>> I'm not sure what you mean about the regulator not being "quiet". The LM723
>> is a simple linear I.C.; no switching noise and no acoustical noise.
>...
>
>It's true that the 723 is a really ancient IC - it was designed back in
>the 70's I believe.

Ancient is not always bad, because the 723 was way ahead of its time.
The 723 survived the introduction of convenient 'drop-in' regulator ICs
like the 7812 and 317 because that first generation of 3-pin regulators
had inferior performance in critical applications. Only in more recent
years have more modern 3-pin and 5-pin regulators moved ahead of the
ancient 723.

When production lines changed over to lead-free manufacturing processes,
many of those very early ICs were discontinued. The 723 is one of the
few that 'made the cut' because there is still nothing else quite like
it.

>It is also true that there are some pitfalls with using it that can
>trap the unwary.  But with proper design it can be made to work just
>fine.
>
The 723 is not a plug-and-play circuit block; it's really a 'kit of
parts' on a chip, with all of its functions  - voltage reference,
op-amp, compensation - accessible on separate pins. These functions can
be configured in several different ways, which means that the 723 will
always require some good old 1970s-style analog circuit design... which
includes plenty of opportunities for the designer to make mistakes.

The classic reference for this style of detailed, up-close circuit
design is 'The Art of Electronics' by Horowitz and Hill - one of the few
college-level engineering texts that belongs on the workbench as well.
Highly recommended.


--

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
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[Alan Hawrylyshen]

On Sep 19, 2012, at 9:09, Ian White GM3SEK <[hidden email]> wrote:

> The classic reference for this style of detailed, up-close circuit
> design is 'The Art of Electronics' by Horowitz and Hill - one of the few
> college-level engineering texts that belongs on the workbench as well.


Highly recommended.

I heartily agree. The Art of Electronics is worth it's weight in gold. Comprehensive and surprisingly accessible for the technical depth.

Alan
K2ACK

Sent from my mobile device.


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