Elecraft

Silent power supply for a K3s

Classic

List

Threaded

25 messages Options

Elecraft mailing list

Silent power supply for a K3s

Peter,

Check out the high amperage 13,8 volt power supplies offered by Samlex
America at the following link, and in particular their 100-amp -plus
(continuous) supplies where the fans do not activate for low draws. You had
mentioned something about price not being so important. These ain't cheap.
73 de Mark .w2or.

https://www.samlexamerica.com/products/ProductsList.aspx?cid=S3

______________________________________________________________
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
Message delivered to [hidden email]

Bob McGraw - K4TAX

Re: Silent power supply for a K3s

I find Mark's point very important.   Obtain and use a supply which is
more than adequate for the service or load. Thus a 25 amp supply
feeding a radio drawing 20+ amps will need lots of cooling.   This is
not the way to do it.   Get a 50 amp supply for a radio drawing 20+ amps
and the fan(s) will likely never come on.     Go the cheap way and get
the cheap results.    Do it right and be happy.   Don't be a cheap ham
and then complain about the product you purchased.

There is more to choosing a power supply than volts and amps. How about
duty cycle? And CCS rated supplies vs. ICAS rated supplies.   Humm.......

73

Bob, K4TAX

On 6/9/2019 2:12 PM, Mark Murray via Elecraft wrote:
> Peter,
>
> Check out the high amperage 13,8 volt power supplies offered by Samlex
> America at the following link, and in particular their 100-amp -plus
> (continuous) supplies where the fans do not activate for low draws. You had
> mentioned something about price not being so important. These ain't cheap.
> 73 de Mark .w2or.
>

______________________________________________________________
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
Message delivered to [hidden email]

Ken Winterling

Re: Silent power supply for a K3s

I use an IOTA DLS-55 SMPS power supply (https://www.iotaengineering.com/
dls55.htm). It provides 55 amps, doesn’t produce RFI, is audibly quiet,
and rugged. Mine is mounted under the radio table and is on 24/7/365.. I
never hear it. Iota also makes them in other output currents and voltages.

Ken
WA2LBI

On Sun, Jun 9, 2019 at 3:27 PM Bob McGraw K4TAX <[hidden email]> wrote:

> I find Mark's point very important. Obtain and use a supply which is
> more than adequate for the service or load. Thus a 25 amp supply
> feeding a radio drawing 20+ amps will need lots of cooling. This is
> not the way to do it. Get a 50 amp supply for a radio drawing 20+ amps
> and the fan(s) will likely never come on. Go the cheap way and get
> the cheap results. Do it right and be happy. Don't be a cheap ham
> and then complain about the product you purchased.
>
> There is more to choosing a power supply than volts and amps. How about
> duty cycle? And CCS rated supplies vs. ICAS rated supplies. Humm.......
>
> 73
>
> Bob, K4TAX
>
>
> On 6/9/2019 2:12 PM, Mark Murray via Elecraft wrote:
> > Peter,
> >
> > Check out the high amperage 13,8 volt power supplies offered by Samlex
> > America at the following link, and in particular their 100-amp -plus
> > (continuous) supplies where the fans do not activate for low draws. You
> had
> > mentioned something about price not being so important. These ain't
> cheap.
> > 73 de Mark .w2or.
> >
>
> ______________________________________________________________
> 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
> Message delivered to [hidden email]

Rick WA6NHC-2

Re: Silent power supply for a K3s

In reply to this post by Bob McGraw - K4TAX

The issue with oversizing it is (for the energy conscious) a linear
supply demands more, ALL the time (it's inefficient with energy).

In some places it matters because of the KwH costs. pennies turn into
dollars.

(Not here, I was used to the higher prices and after I moved here, I
just stopped caring because the costs were 1/3 or less. I've even been
known to <gasp> run the air conditioner here!)

Rick nhc

On 6/9/2019 12:26 PM, Bob McGraw K4TAX wrote:

> I find Mark's point very important.   Obtain and use a supply which is
> more than adequate for the service or load. Thus a 25 amp supply
> feeding a radio drawing 20+ amps will need lots of cooling.   This is
> not the way to do it.   Get a 50 amp supply for a radio drawing 20+
> amps and the fan(s) will likely never come on.     Go the cheap way
> and get the cheap results.    Do it right and be happy.   Don't be a
> cheap ham and then complain about the product you purchased.
>
> There is more to choosing a power supply than volts and amps. How
> about duty cycle? And CCS rated supplies vs. ICAS rated supplies.
> Humm.......
>
> 73
>
> Bob, K4TAX
>
>
> On 6/9/2019 2:12 PM, Mark Murray via Elecraft wrote:
>> Peter,
>>
>> Check out the high amperage 13,8 volt power supplies offered by Samlex
>> America at the following link, and in particular their 100-amp -plus
>> (continuous) supplies where the fans do not activate for low draws.
>> You had
>> mentioned something about price not being so important. These ain't
>> cheap.
>> 73 de Mark .w2or.
>>
>
> ______________________________________________________________
> 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
> Message delivered to [hidden email]

Elecraft mailing list

Re: Silent power supply for a K3s

In reply to this post by Ken Winterling

Somewhere around 1980 I was talked into buying a power supply at a hamfest by my good friend who was a great technician. He told me it was a terrific deal. He was right. I don't remember what I paid for it but I know it was lessthan $100. It was a 56 amp rack mounted Llamda metered supply. The model is an LM G12-M. I believe it weighs about 75 pounds. I used to have it in a relay rack at my old QTH shack. In my present shack I have it sitting on a furnituredolly which makes it easy to roll around on the floor. It sits under my desk. It developed an audible arc when turned on so I leave it on 24 - 7. I'm sure the new cost of it would be pretty high but I'm so glad I followed my friend's advice tobuy it. No RFI and no fans.
BillK3WJV

On Sunday, June 9, 2019, 4:30:07 PM EDT, Ken Winterling <[hidden email]> wrote:

I use an IOTA DLS-55 SMPS power supply (https://www.iotaengineering.com/
dls55.htm). It provides 55 amps, doesn’t produce RFI, is audibly quiet,
and rugged. Mine is mounted under the radio table and is on 24/7/365.. I
never hear it. Iota also makes them in other output currents and voltages.

Ken
WA2LBI

On Sun, Jun 9, 2019 at 3:27 PM Bob McGraw K4TAX <[hidden email]> wrote:

______________________________________________________________
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
Message delivered to [hidden email]
______________________________________________________________
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
Message delivered to [hidden email]

Bill-3

Re: Silent power supply for a K3s

I have several Power Werx switchers and prefer them for their size over
the heavy analog supplies. Fans are not a problem (actually, I hear
nothing from them at all) - IF you design your radio desk for proper
equipment placement. Place the power supply at your right hand - and you
WILL hear noise, XFMR, fan, etc.

It is amazing what proper station design/construction can do for making
silence. Open faced metal shelving and bare desktops don't cut it.

Just for grins, I put one of those Nanoxia fans in my IC-7300 and
silenced it completely. Worth the few dollars and effort. No temperature
changes noted. Hmmm - KPA500?????

______________________________________________________________
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
Message delivered to [hidden email]

Alan Corbeth

Re: Silent power supply for a K3s

I have an Astron RS35 power Supply purchased in 1991. There was a period where I didn’t use it for ten years. Now it’s in use daily and so far it continues to be totally quiet.

Alan
K7FH

> On Jun 10, 2019, at 3:56 AM, Bill <[hidden email]> wrote:
>
> I have several Power Werx switchers and prefer them for their size over the heavy analog supplies. Fans are not a problem (actually, I hear nothing from them at all) - IF you design your radio desk for proper equipment placement. Place the power supply at your right hand - and you WILL hear noise, XFMR, fan, etc.
>
> It is amazing what proper station design/construction can do for making silence. Open faced metal shelving and bare desktops don't cut it.
>
> Just for grins, I put one of those Nanoxia fans in my IC-7300 and silenced it completely. Worth the few dollars and effort. No temperature changes noted. Hmmm - KPA500?????
>
>
> ______________________________________________________________
> 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
> Message delivered to [hidden email]

donovanf

Re: Silent power supply for a K3s

I have twelve RS-35M power supplies and all are completely quiet.

----- Original Message -----

From: "Alan Corbeth" <[hidden email]>
To: "Bill" <[hidden email]>
Cc: "Elecraft International Group" <[hidden email]>
Sent: Tuesday, June 11, 2019 12:04:02 AM
Subject: Re: [Elecraft] Silent power supply for a K3s

I have an Astron RS35 power Supply purchased in 1991. There was a period where I didn’t use it for ten years. Now it’s in use daily and so far it continues to be totally quiet.

Alan
K7FH

Bob Nielsen-4

Re: Silent power supply for a K3s

In reply to this post by Alan Corbeth

The Astrons are quiet and pretty reliable. I have had a RS20 since 1980
and the only problem I had was cured by replacing the regulator chip
about 35 years ago.

Bob, N7XY

On 6/10/19 5:04 PM, Alan Corbeth wrote:

> I have an Astron RS35 power Supply purchased in 1991. There was a period where I didn’t use it for ten years. Now it’s in use daily and so far it continues to be totally quiet.
>
> Alan
> K7FH
>
>> On Jun 10, 2019, at 3:56 AM, Bill <[hidden email]> wrote:
>>
>> I have several Power Werx switchers and prefer them for their size over the heavy analog supplies. Fans are not a problem (actually, I hear nothing from them at all) - IF you design your radio desk for proper equipment placement. Place the power supply at your right hand - and you WILL hear noise, XFMR, fan, etc.
>>
>> It is amazing what proper station design/construction can do for making silence. Open faced metal shelving and bare desktops don't cut it.
>>
>> Just for grins, I put one of those Nanoxia fans in my IC-7300 and silenced it completely. Worth the few dollars and effort. No temperature changes noted. Hmmm - KPA500?????
>>
>>
>> ______________________________________________________________
>> 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
>> Message delivered to [hidden email]
> ______________________________________________________________
> 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
> Message delivered to [hidden email]

Elecraft mailing list

Re: Silent power supply for a K3s

Another vote for the Astron Power Supplies they work well.

Use the shortest run between the PS and radio you can and of a heavy gauge wire.

On Tuesday, June 11, 2019, 6:15:14 PM EDT, Bob Nielsen - N7XY <[hidden email]> wrote:

The Astrons are quiet and pretty reliable. I have had a RS20 since 1980
and the only problem I had was cured by replacing the regulator chip
about 35 years ago.

Bob, N7XY

On 6/10/19 5:04 PM, Alan Corbeth wrote:

Bob McGraw - K4TAX

Re: Silent power supply for a K3s

I've found a good source for power supply wire for the DC connections.
Automotive primary wire, #10 AWG. This wire is made using many small
strands which make it very flexible. Various colors are available.   I
use Red {DC Pos}, Black {DC Neg} and White {equipment bonding wire}.
Also I use the proper size for the wire and screw ring terminals {no
spade or Y lugs} fitted on each end.

I'm and old fashion fellow and and was taught to crimp with the correct
crimping tool. I've seen too many hams use the "mash-on" method, thus
using what ever tool happens to be in the tool box.    A proper crimping
tool is designed for the specific connector and sleeve size and does not
distort the sleeve.   Yea, a good crimping tool may cost you $25 to $35
but it is sure worth it not having to worry about lousy connections.

As a test, crimp a lug on a piece of wire. Using pliers, try to pull it
off. If you can, it may be the wrong size lug for the wire OR it is
not properly crimped.   If the wire breaks first, you have a good crimp.

73

Bob, K4TAX

On 6/12/2019 8:17 AM, Harry Yingst via Elecraft wrote:

> Another vote for the Astron Power Supplies they work well.
>
> Use the shortest run between the PS and radio you can and of a heavy gauge wire.
>
>
>
> On Tuesday, June 11, 2019, 6:15:14 PM EDT, Bob Nielsen - N7XY <[hidden email]> wrote:
>
> The Astrons are quiet and pretty reliable. I have had a RS20 since 1980
> and the only problem I had was cured by replacing the regulator chip
> about 35 years ago.
>
> Bob, N7XY
>
> On 6/10/19 5:04 PM, Alan Corbeth wrote:
>> I have an Astron RS35 power Supply purchased in 1991. There was a period where I didn’t use it for ten years. Now it’s in use daily and so far it continues to be totally quiet.
>>
>> Alan
>> K7FH
>>
>>> On Jun 10, 2019, at 3:56 AM, Bill <[hidden email]> wrote:
>>>
>>> I have several Power Werx switchers and prefer them for their size over the heavy analog supplies. Fans are not a problem (actually, I hear nothing from them at all) - IF you design your radio desk for proper equipment placement. Place the power supply at your right hand - and you WILL hear noise, XFMR, fan, etc.
>>>
>>> It is amazing what proper station design/construction can do for making silence. Open faced metal shelving and bare desktops don't cut it.
>>>
>>> Just for grins, I put one of those Nanoxia fans in my IC-7300 and silenced it completely. Worth the few dollars and effort. No temperature changes noted. Hmmm - KPA500?????
>>>
>>>
>>> ______________________________________________________________
>>> 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
>>> Message delivered to [hidden email]
>> ______________________________________________________________
>> 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
>> Message delivered to [hidden email]
> ______________________________________________________________
> 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
> Message delivered to [hidden email]
> ______________________________________________________________
> 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
> Message delivered to [hidden email]

VE3NR

Re: Silent power supply for a K3s

In reply to this post by Elecraft mailing list

Linear PSs are not noisy as far as I know. You're comparing apples and
oranges!! ;-))

Bert VE3NR

On 6/12/2019 9:17 AM, Harry Yingst via Elecraft wrote:

Bob McGraw - K4TAX

Re: Silent power supply for a K3s

Regarding "heavy gauge wire", I suggest one measure the voltage drop
using a DVM connected direct between the power supply Pos terminal and
the radio Pos terminal.   Likewise do the same for the Neg DC line.
Put the radio in CW mode and close the key for rated output.    If one
finds more than 0.25 volts drop in either the Pos or Neg line, I'd say
that attention to the power cable and connectors would be in order.
Also measure between radio ground and power supply ground.   Again a
voltage value greater than 0.25 volts indicates attention to the power
distribution system and station equipment grounding is needed.

73

Bob, K4TAX

On 6/12/2019 9:17 AM, Harry Yingst via Elecraft wrote:
>> Another vote for the Astron Power Supplies they work well.
>>
>> Use the shortest run between the PS and radio you can and of a heavy
>> gauge wire.
>>
>>
>>

______________________________________________________________
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
Message delivered to [hidden email]

Don Wilhelm

Re: Silent power supply for a K3s

After consulting copper wire tables and typical connection resistances,
I can present the following analysis for a 20 amp load:

Often hams power their 100 watt transceivers through DC distribution
devices such as a RigRunner which will contribute to the voltage drop.
Also in-line fuses will contribute to voltage drop.

Connection resistance contributes .05 volt loss under a 20 amp load for
each contact point, you have 6 contact points in the path for a fused
RigRunner plus two in the APP connector at the transceiver, plus the
connection to the power supply for a total of 10 contact points. You
have to consider the negative path as well as the positive. So that is
a total of 0.5 volts of the total voltage drop.

By contrast, a 5 foot length under a 20 amp load of #12 wire has 0.1588
ohms (in both conductors) for a voltage drop of 0.3176 volts, and #10
wire a drop of 0.1998 volts.

So conclusion is that while increasing the wire size can reduce the
voltage drop, the main contributor is in the power distribution system.

A path direct from the power supply terminals can be expected to have a
0.5 volt drop with 5 feet of #12 wire to the inside of the K3. and #10
wire can have a 0.4 volt drop - the difference is only slightly significant.

Conclusion - in a 5 foot power cable run, the difference between #10 and
#12 wire is only 0.1 volts (0.05 volts in each of the positive and
negative leads) - the major contributor is the number of contact points.

So for those who choose to measure the voltage drop from the power
supply terminals to the APP connector on the outside of the K3, you
should measure about 0.2 volts in each conductor with #12 wire and 0.15
volts with #10 wire. If it is much more than that, check your power
supply connection tightness and your crimp connections.

Run the transceiver direct from a power supply using ring terminals
instead of routing through a power distribution accessory.

73,
Don W3FPR

On 6/12/2019 6:29 PM, Bob McGraw K4TAX wrote:

> Regarding "heavy gauge wire", I suggest one measure the voltage drop
> using a DVM connected direct between the power supply Pos terminal and
> the radio Pos terminal.   Likewise do the same for the Neg DC line. Put
> the radio in CW mode and close the key for rated output.    If one finds
> more than 0.25 volts drop in either the Pos or Neg line, I'd say that
> attention to the power cable and connectors would be in order. Also
> measure between radio ground and power supply ground.   Again a voltage
> value greater than 0.25 volts indicates attention to the power
> distribution system and station equipment grounding is needed.
>

Joe Subich, W4TV-4

Re: Silent power supply for a K3s

On 2019-06-12 7:55 PM, Don Wilhelm wrote:
> Connection resistance contributes .05 volt loss under a 20 amp load
> for each contact point, you have 6 contact points in the path for a
> fused RigRunner plus two in the APP connector at the transceiver,
> plus the connection to the power supply for a total of 10 contact
> points. You have to consider the negative path as well as the
> positive. So that is a total of 0.5 volts of the total voltage drop.

This assumes the APP connections into and out of the RigRunner are
assembled correctly (contacts properly aligned). If they are not,
the contact resistance will be significantly higher.

Further, the 20A current (and the voltage drop I^2*R) may be
significantly higher in the cable between the power supply and
RigRunner. Again, this will result in *MORE THAN* 0.5 volts of
total voltage drop when using a RigRunner type power distribution
system.

Further, while one may measure 20A in transmit (using the K3 internal
"meter") there is a significant time constant, particularly in SSB
operation. The actual *peak* current may be closer to 30 - 35A than
to 17 - 20A. Since voltage drop in power supply cables and power
distribution system are related to the *current squared* the actual
*maximum* voltage drop (and loss of voltage regulation, increase in
transmit IMD, etc.) will be worse that the static analysis would
indicate.

73,

... Joe, W4TV

On 2019-06-12 7:55 PM, Don Wilhelm wrote:

> After consulting copper wire tables and typical connection resistances,
> I can present the following analysis for a 20 amp load:
>
> Often hams power their 100 watt transceivers through DC distribution
> devices such as a RigRunner which will contribute to the voltage drop.
> Also in-line fuses will contribute to voltage drop.
>
> Connection resistance contributes .05 volt loss under a 20 amp load for
> each contact point, you have 6 contact points in the path for a fused
> RigRunner plus two in the APP connector at the transceiver, plus the
> connection to the power supply for a total of 10 contact points. You
> have to consider the negative path as well as the positive. So that is
> a total of 0.5 volts of the total voltage drop.
>
> By contrast, a 5 foot length under a 20 amp load of #12 wire has 0.1588
> ohms (in both conductors) for a voltage drop of 0.3176 volts, and #10
> wire a drop of 0.1998 volts.
>
> So conclusion is that while increasing the wire size can reduce the
> voltage drop, the main contributor is in the power distribution system.
>
> A path direct from the power supply terminals can be expected to have a
> 0.5 volt drop with 5 feet of #12 wire to the inside of the K3. and #10
> wire can have a 0.4 volt drop - the difference is only slightly
> significant.
>
> Conclusion - in a 5 foot power cable run, the difference between #10 and
> #12 wire is only 0.1 volts (0.05 volts in each of the positive and
> negative leads) - the major contributor is the number of contact points.
>
> So for those who choose to measure the voltage drop from the power
> supply terminals to the APP connector on the outside of the K3, you
> should measure about 0.2 volts in each conductor with #12 wire and 0.15
> volts with #10 wire. If it is much more than that, check your power
> supply connection tightness and your crimp connections.
>
> Run the transceiver direct from a power supply using ring terminals
> instead of routing through a power distribution accessory.
>
> 73,
> Don W3FPR
>
> On 6/12/2019 6:29 PM, Bob McGraw K4TAX wrote:
>> Regarding "heavy gauge wire", I suggest one measure the voltage drop
>> using a DVM connected direct between the power supply Pos terminal and
>> the radio Pos terminal.   Likewise do the same for the Neg DC line.
>> Put the radio in CW mode and close the key for rated output.    If one
>> finds more than 0.25 volts drop in either the Pos or Neg line, I'd say
>> that attention to the power cable and connectors would be in order.
>> Also measure between radio ground and power supply ground.   Again a
>> voltage value greater than 0.25 volts indicates attention to the power
>> distribution system and station equipment grounding is needed.
>>

Elecraft mailing list

Re: Silent power supply for a K3s

In reply to this post by Elecraft mailing list

Easy way out of this mess, if a little expensive...

A big PSU dedicated to the rig(s), implementing "Remote Sensing" so at a
distribution point close to the radio(s) the DC voltage is held
constant, irrespective of the cable length from the PSU.

This power supply should have a proper overload (and over voltage)
protection scheme too, not only to protect itself, but the radio(s)
also. And safety resistors between + and +s, also between - and -s
terminals. (Prevents expensive embarrassment, if a sense line fails!)

Then use a smaller PSU for the low power accessories, with suitable fusing.

Any QRO power amp, needing really high current, should have it's own
independent dedicated PSU, again with remote sensing to keep the voltage
at the PA as near constant as it can be, and the resulting high DC
currents, purely between the PA and it's PSU.

Just my way of doing things, to keep the high DC currents out of the RF
cabling.

Google "power supply remote sensing" for more info.

73. Dave G0WBX.

--
Created on and sent from a Unix like PC running and using free and open source software:

______________________________________________________________
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
Message delivered to [hidden email]

Kidder, George

Re: Terminal resistance

In reply to this post by Don Wilhelm

Interesting data, Don. I wonder if there is any information about
resistance variations between soldered and crimped terminals. One might
think that, with stranded wire, even a good crimp connection might not
solidly involve all of the strands, and might additionally deteriorate
with time since oxygen could get between the strands. A good solder job
should wet the wire through and (additionally) exclude oxygen. This
wouldn't be easy to measure, for sure, but these engineers are cleaver
people!

73 - George, W3HBM

On 6/12/2019 7:55 PM, Don Wilhelm wrote:

> [This message came from an external source. If suspicious, report to
> [hidden email]<mailto:[hidden email]>]
>
> After consulting copper wire tables and typical connection resistances,
> I can present the following analysis for a 20 amp load:
>
> Often hams power their 100 watt transceivers through DC distribution
> devices such as a RigRunner which will contribute to the voltage drop.
> Also in-line fuses will contribute to voltage drop.
>
> Connection resistance contributes .05 volt loss under a 20 amp load for
> each contact point, you have 6 contact points in the path for a fused
> RigRunner plus two in the APP connector at the transceiver, plus the
> connection to the power supply for a total of 10 contact points. You
> have to consider the negative path as well as the positive. So that is
> a total of 0.5 volts of the total voltage drop.
>
> By contrast, a 5 foot length under a 20 amp load of #12 wire has 0.1588
> ohms (in both conductors) for a voltage drop of 0.3176 volts, and #10
> wire a drop of 0.1998 volts.
>
> So conclusion is that while increasing the wire size can reduce the
> voltage drop, the main contributor is in the power distribution system.
>
> A path direct from the power supply terminals can be expected to have a
> 0.5 volt drop with 5 feet of #12 wire to the inside of the K3. and #10
> wire can have a 0.4 volt drop - the difference is only slightly
> significant.
>
> Conclusion - in a 5 foot power cable run, the difference between #10 and
> #12 wire is only 0.1 volts (0.05 volts in each of the positive and
> negative leads) - the major contributor is the number of contact points.
>
> So for those who choose to measure the voltage drop from the power
> supply terminals to the APP connector on the outside of the K3, you
> should measure about 0.2 volts in each conductor with #12 wire and 0.15
> volts with #10 wire. If it is much more than that, check your power
> supply connection tightness and your crimp connections.
>
> Run the transceiver direct from a power supply using ring terminals
> instead of routing through a power distribution accessory.
>
> 73,
> Don W3FPR
>
> On 6/12/2019 6:29 PM, Bob McGraw K4TAX wrote:
>> Regarding "heavy gauge wire", I suggest one measure the voltage drop
>> using a DVM connected direct between the power supply Pos terminal and
>> the radio Pos terminal.   Likewise do the same for the Neg DC line. Put
>> the radio in CW mode and close the key for rated output.    If one finds
>> more than 0.25 volts drop in either the Pos or Neg line, I'd say that
>> attention to the power cable and connectors would be in order. Also
>> measure between radio ground and power supply ground.   Again a voltage
>> value greater than 0.25 volts indicates attention to the power
>> distribution system and station equipment grounding is needed.
>>
> ______________________________________________________________
> 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
> Message delivered to [hidden email]

Nate Bargmann

Re: Terminal resistance

* On 2019 16 Jun 18:50 -0500, Kidder, George wrote:
> Interesting data, Don. I wonder if there is any information about
> resistance variations between soldered and crimped terminals. One might
> think that, with stranded wire, even a good crimp connection might not
> solidly involve all of the strands, and might additionally deteriorate
> with time since oxygen could get between the strands. A good solder job
> should wet the wire through and (additionally) exclude oxygen. This
> wouldn't be easy to measure, for sure, but these engineers are cleaver
> people!

For what it is worth, the company I worked for prohibited the use of
soldered connectors for terminating bonding or power wiring. Especially
with regard to bonding, dissipating any lightning strike energy through
a soldered connector could cause it to enough to melt the solder. In
doing some microwave site upgrades I did pull out a previous generation
of bonding wiring that was soldered and some connectors had signs of
being heated since installation.

In my shack I use crimp connectors and a quality crimping tool with no
problems.

73, Nate, N0NB

--

"The optimist proclaims that we live in the best of all
possible worlds. The pessimist fears this is true."

Web: https://www.n0nb.us GPG key: D55A8819 GitHub: N0NB
______________________________________________________________
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
Message delivered to [hidden email]

Don Wilhelm

Re: Terminal resistance

In reply to this post by Kidder, George

George,

Solid wire will eventually break if it is flexed - and it will break
right where the terminals are attached.

Stranded wire that is soldered will also break - right where the end of
the solder that wicked up the wire stops.

The best is stranded wire with crimped connections made with a proper
crimping tool. Done properly, that should result in an air-tight
connection that should not oxidize.

In order to do that, you must use a crimping tool that is sized for the
wire and terminal that you are using. Crimping with just any tool will
"not get it".

If you do not have the proper crimping tool, soldering is OK, but
support the wire for about 2 inches away from the soldered terminal so
there is no chance that it can flex.

73,
Don W3FPR

On 6/16/2019 7:22 PM, Kidder, George wrote:
> Interesting data, Don. I wonder if there is any information about
> resistance variations between soldered and crimped terminals. One might
> think that, with stranded wire, even a good crimp connection might not
> solidly involve all of the strands, and might additionally deteriorate
> with time since oxygen could get between the strands. A good solder job
> should wet the wire through and (additionally) exclude oxygen. This
> wouldn't be easy to measure, for sure, but these engineers are cleaver
> people!
______________________________________________________________
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
Message delivered to [hidden email]

ANDY DURBIN

Terminal resistance

In reply to this post by Kidder, George

"but these engineers are cleaver people!"

Engineers with slide rules are arguably less of a threat than those with cleavers.

Resistance is futile...

73,
Andy, k3wyc
______________________________________________________________
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
Message delivered to [hidden email]