Date   

Re: Field Day

Wayne Dillon
 

Chas,
You're in seriously good company!
Blessings
Wayne - KC0PMH

On Mon, May 11, 2015 at 7:36 PM, Charles Powell doctorcwp@... [4sqrp] <4sqrp@...> wrote:
 

I’m a crazy old CW op.  No PSK or RTTY for me.


72,

Chas - NK8O


On May 11, 2015, at 18:26, John R. Lonigro <jonigro@...> wrote:

Chas:

1) Calling CQ at 5W might be tough.  If you can do it, go for it, but chances are someone else won't hear you, will think the frequency is clear, and will be on top of your signal.  The bands are very crowded on Field Day.  Our club (St. Louis QRP Society) uses "Search and Pounce" almost exclusively.

You are correct that you can power the laptop from the mains, as long as you aren't using it for digital communication.  Performing logging using commercial mains or a generator won't affect your 10 pts/QSO.  If you use it for PSK or RTTY or other digital modes, that's a different story.

Good luck and 72,

John AA0VE

On 05/11/2015 06:53 PM, doctorcwp@... [4sqrp] wrote:
 

I am free for Field Day this year (how did it happen?) so I’m going to operate QRP 1B-battery.  The lure of 10 points per QSO is pretty strong. Does anyone have any recommendations for setting up a station?  I have the KX3, so the radio is not a problem.  I need to do a little site survey, but where I am considering I can set up a near vertical long wire.  As a second antenna, I was thinking about hanging a very large horizontal loop for NVIS.


I read some of the information that Terry WA0ITP posted in the past, i.e., call CQ, don't act like you're QRP, and just go for it.  Sound advice.


Also, my laptop, a Macbook Air, only lasts 5 or 6 hours on its battery.  It's legal to power the computer with a generator, but I don't have one.  Maybe I should try to find a 12 volt inverter to charge from the car battery?  I checked with ARRL a few years ago and this is legal, as long as you don't use the motorized generators to power the radio.


Comments?


Chas - NK8O









--
http://www.qsl.net/kc0pmh/   Under construction but please visit anyway.
 
QRP -  EFFICIENCY AND SKILL, NOT POWER. 
 
I'm British by birth but American by CHOICE!

Jesus came to pay a debt He didn't owe because we owe a debt we cannot pay...

The Lord bless you and keep you
The Lord make His face shine upon you, and be gracious unto you
The Lord lift up his contenance upon you and give you peace.

God Bless from Wayne Dillon - KC0PMH

Joshua 24:14-15
2 Cor 5:17
1 Jn 2:17
 
Membership Chairman - 4SQRP Group
4SQRP #95
FISTS 17184
FPQRP #342 (Flying Pigs QRP Club)
NAQCC # 0759
QRP-ARCI #11505
SKCC #1155T
CW Ragchewers Anonymous #40
SOC #848
30MDG#1176
NEQRP #693
GORC #192
DMC (Digital Modes Club) # 06686


Monday Night SSB Net SWL Report

dekle@...
 

I heard Wayne (KC0PMH) call CQ twice.

He was 59 here, making it over the S7 noise nicely.

Nothing else heard.


73

Bill

KV6Z




Re: Field Day

Charles W. Powell
 

I’m a crazy old CW op.  No PSK or RTTY for me.

72,

Chas - NK8O


On May 11, 2015, at 18:26, John R. Lonigro <jonigro@...> wrote:

Chas:

1) Calling CQ at 5W might be tough.  If you can do it, go for it, but chances are someone else won't hear you, will think the frequency is clear, and will be on top of your signal.  The bands are very crowded on Field Day.  Our club (St. Louis QRP Society) uses "Search and Pounce" almost exclusively.

You are correct that you can power the laptop from the mains, as long as you aren't using it for digital communication.  Performing logging using commercial mains or a generator won't affect your 10 pts/QSO.  If you use it for PSK or RTTY or other digital modes, that's a different story.

Good luck and 72,

John AA0VE

On 05/11/2015 06:53 PM, doctorcwp@... [4sqrp] wrote:
 

I am free for Field Day this year (how did it happen?) so I’m going to operate QRP 1B-battery.  The lure of 10 points per QSO is pretty strong. Does anyone have any recommendations for setting up a station?  I have the KX3, so the radio is not a problem.  I need to do a little site survey, but where I am considering I can set up a near vertical long wire.  As a second antenna, I was thinking about hanging a very large horizontal loop for NVIS.


I read some of the information that Terry WA0ITP posted in the past, i.e., call CQ, don't act like you're QRP, and just go for it.  Sound advice.


Also, my laptop, a Macbook Air, only lasts 5 or 6 hours on its battery.  It's legal to power the computer with a generator, but I don't have one.  Maybe I should try to find a 12 volt inverter to charge from the car battery?  I checked with ARRL a few years ago and this is legal, as long as you don't use the motorized generators to power the radio.


Comments?


Chas - NK8O







Re: Field Day

John Lonigro
 

Chas:

1) Calling CQ at 5W might be tough.  If you can do it, go for it, but chances are someone else won't hear you, will think the frequency is clear, and will be on top of your signal.  The bands are very crowded on Field Day.  Our club (St. Louis QRP Society) uses "Search and Pounce" almost exclusively.

You are correct that you can power the laptop from the mains, as long as you aren't using it for digital communication.  Performing logging using commercial mains or a generator won't affect your 10 pts/QSO.  If you use it for PSK or RTTY or other digital modes, that's a different story.

Good luck and 72,

John AA0VE

On 05/11/2015 06:53 PM, doctorcwp@... [4sqrp] wrote:
 

I am free for Field Day this year (how did it happen?) so I’m going to operate QRP 1B-battery.  The lure of 10 points per QSO is pretty strong. Does anyone have any recommendations for setting up a station?  I have the KX3, so the radio is not a problem.  I need to do a little site survey, but where I am considering I can set up a near vertical long wire.  As a second antenna, I was thinking about hanging a very large horizontal loop for NVIS.


I read some of the information that Terry WA0ITP posted in the past, i.e., call CQ, don't act like you're QRP, and just go for it.  Sound advice.


Also, my laptop, a Macbook Air, only lasts 5 or 6 hours on its battery.  It's legal to power the computer with a generator, but I don't have one.  Maybe I should try to find a 12 volt inverter to charge from the car battery?  I checked with ARRL a few years ago and this is legal, as long as you don't use the motorized generators to power the radio.


Comments?


Chas - NK8O






Re: SSB?

Richard Dickerson
 

I'll try but QRN9+

Sent from my iPhone

On Apr 20, 2015, at 20:48, Michael McEwen mcewenk5osa@... [4sqrp] <4sqrp@...> wrote:

 

Am on 7.285 and vicinity...do no hear anyone from 4sqrp.  Also, nothing on QRPSPOTS...Is the net running?
72,
Doc K5OSA - QTH: EM04sr
ARRL  
4SQRP #801 - NAQCC #7625 - SKCC #10098 - FISTS #17157 - OMISS #9886
LFSARC (Lawton/Fort Sill Amateur Radio Club)

Michael T McEwen
Lt Col, US Army, Ret

Cellular Phone:  580 919-9205
Residence:  580 529-3412


Re: Low Cost Dummy Load [1 Attachment]

dekle <dekle@...>
 


To maintain the 100w power rating, the 2133.3 Ohm parallel resistor only has to be rated for 1.84 w.
 
Bill
KV6Z
 
 

----- Original Message -----
Sent: Monday, May 11, 2015 1:49 PM
Subject: [4sqrp] Low Cost Dummy Load [1 Attachment]

 

This is my new low cost dummy load, made with a Caddock thick film non-inductive resistor. This one is 50 ohms at 1%, and rated at 100 watts, and costs about $11.00 from Mouser or Digikey. I realize the current heat sink will not be adequate for 100 watts, but it will suffice for the 5 and 50 watt calibrations of my K3, it does get warm to the touch. Only problem is resistance measures 51.2 ohms. What value of a parallel resistor would bring that down to 50 ohms? I calculate 1234.56 ohms or 1.2 K. Is that right? Also what would the power rating of the resistor need to be? Thanks.

Darryl, KK5IB


Field Day

Charles W. Powell
 

I am free for Field Day this year (how did it happen?) so I’m going to operate QRP 1B-battery.  The lure of 10 points per QSO is pretty strong. Does anyone have any recommendations for setting up a station?  I have the KX3, so the radio is not a problem.  I need to do a little site survey, but where I am considering I can set up a near vertical long wire.  As a second antenna, I was thinking about hanging a very large horizontal loop for NVIS.


I read some of the information that Terry WA0ITP posted in the past, i.e., call CQ, don't act like you're QRP, and just go for it.  Sound advice.


Also, my laptop, a Macbook Air, only lasts 5 or 6 hours on its battery.  It's legal to power the computer with a generator, but I don't have one.  Maybe I should try to find a 12 volt inverter to charge from the car battery?  I checked with ARRL a few years ago and this is legal, as long as you don't use the motorized generators to power the radio.


Comments?


Chas - NK8O





Re: Low Cost Dummy Load

Don Wilhelm <w3fpr@...>
 

A quick approximation is that the 2133 ohm resistor will carry approximately 1/40th of the total power - so for a full 100 watt rating a 2.5 watt resistor will do.
5 426 ohm 1/2 watt resistors will do the job fine.  You might just want to use 5 470 ohm resistors in series and call it 'good enough' (50.13333 ohms).

73,
Don W3FPR


On 5/11/2015 7:28 PM, 'dekle' dekle@... [4sqrp] wrote:
 



Darryl:,
 
Let 'x' = the value of a resistor in parallel with a 51.2 Ohm resistor to yield 50 ohms equivalent resistance.
 
50 = 51.2 x / (51.2 + x)     (Product over the sum for 2 resistors in parallel.)
2560  +  50 x = 51.2 x       (Multiply both sides by (51.2 + x)).
2560 = 1.2 x                      (Subtract 50 x from both sides.)
x = 2133.3 ohms                (Divide both sides by 1.2)
 
Power rating coming soon........
 
73
Bill
KV6Z
 
 
 
 
----- Original Message -----
Sent: Monday, May 11, 2015 1:49 PM
Subject: [4sqrp] Low Cost Dummy Load [1 Attachment]

 

This is my new low cost dummy load, made with a Caddock thick film non-inductive resistor. This one is 50 ohms at 1%, and rated at 100 watts, and costs about $11.00 from Mouser or Digikey. I realize the current heat sink will not be adequate for 100 watts, but it will suffice for the 5 and 50 watt calibrations of my K3, it does get warm to the touch. Only problem is resistance measures 51.2 ohms. What value of a parallel resistor would bring that down to 50 ohms? I calculate 1234.56 ohms or 1.2 K. Is that right? Also what would the power rating of the resistor need to be? Thanks.

Darryl, KK5IB



Re: Low Cost Dummy Load

davemrtn
 

I am not saying it isn't, but I have never heard 'Resistor Tolerance' related to standard deviations.

I am sure it's it used by the manufacturer to control their manufacturing process, but I think at lot of precision resistors (< 5% tolerance) manufactured these days use laser trimming to bring the parts to within rated tolerance.

Maybe there is an engineer in our group that works for a resistor mfg that can give us the full skinny ??


On 5/11/2015 6:12 PM, 'John R. Lonigro' jonigro@... [4sqrp] wrote:
 

I could be wrong, but I don't think a 1% resistor necessarily means the value is within +/- 1%.  I think there are some statistics involved which might say, for example, that the standard deviation is 1%, meaning there are about 40% of the resistors in a particular lot that would fall outside the 1% value and a few percent even falling outside the 2% value.

And, of course, David is right that the error (or at least some of the error) could be coming from the measuring device itself.  As they say, if you have one clock, you know what time it is.  If you have multiple clocks, you have no idea...

72,
John AA0VE


On 05/11/2015 02:20 PM, David Martin davemrtn@... [4sqrp] wrote:
 

Yes but, as you can see from his photo, he paid for a 1% resistor !!

For $11 (+ shipping), I would be calling the vendor.

OR MAYBE, the error is in the device he is using to measure the resistance ??


On 5/11/2015 2:05 PM, Wayne Dillon wayne.dillon@... [4sqrp] wrote:
 
Hi Darryl
Should be 2K2, this equates to 50.0355 Ohms total effective resistance. Not sure on power as the 51.2 is only about 3% of the 2K2. Anyway why worry about the error? the error is less that 3% and that's better than most commercial dummy loads.
Just my $0.02 worth.
Be blessed
Wayne - KC0PMH

On Mon, May 11, 2015 at 1:49 PM, kk5ib01@... [4sqrp] <4sqrp@...> wrote:
 

This is my new low cost dummy load, made with a Caddock thick film non-inductive resistor. This one is 50 ohms at 1%, and rated at 100 watts, and costs about $11.00 from Mouser or Digikey. I realize the current heat sink will not be adequate for 100 watts, but it will suffice for the 5 and 50 watt calibrations of my K3, it does get warm to the touch. Only problem is resistance measures 51.2 ohms. What value of a parallel resistor would bring that down to 50 ohms? I calculate 1234.56 ohms or 1.2 K. Is that right? Also what would the power rating of the resistor need to be? Thanks.

Darryl, KK5IB




--
http://www.qsl.net/kc0pmh/   Under construction but please visit anyway.
 
QRP -  EFFICIENCY AND SKILL, NOT POWER. 
 
I'm British by birth but American by CHOICE!

Jesus came to pay a debt He didn't owe because we owe a debt we cannot pay...

The Lord bless you and keep you
The Lord make His face shine upon you, and be gracious unto you
The Lord lift up his contenance upon you and give you peace.

God Bless from Wayne Dillon - KC0PMH

Joshua 24:14-15
2 Cor 5:17
1 Jn 2:17
 
Membership Chairman - 4SQRP Group
4SQRP #95
FISTS 17184
FPQRP #342 (Flying Pigs QRP Club)
NAQCC # 0759
QRP-ARCI #11505
SKCC #1155T
CW Ragchewers Anonymous #40
SOC #848
30MDG#1176
NEQRP #693
GORC #192
DMC (Digital Modes Club) # 06686

-- 
David Martin - K5DCM
Mountain Home, Ar.
-+-+-+-+-+-+-+-+-+-+-
"It's only "work" if you'd rather be doing something else" - Dean Kamen


-- 
David Martin - K5DCM
Mountain Home, Ar.
-+-+-+-+-+-+-+-+-+-+-
"It's only "work" if you'd rather be doing something else" - Dean Kamen


Re: Low Cost Dummy Load [1 Attachment]

dekle <dekle@...>
 


Darryl:,
 
Let 'x' = the value of a resistor in parallel with a 51.2 Ohm resistor to yield 50 ohms equivalent resistance.
 
50 = 51.2 x / (51.2 + x)     (Product over the sum for 2 resistors in parallel.)
2560  +  50 x = 51.2 x       (Multiply both sides by (51.2 + x)).
2560 = 1.2 x                      (Subtract 50 x from both sides.)
x = 2133.3 ohms                (Divide both sides by 1.2)
 
Power rating coming soon........
 
73
Bill
KV6Z
 
 
 
 

----- Original Message -----
Sent: Monday, May 11, 2015 1:49 PM
Subject: [4sqrp] Low Cost Dummy Load [1 Attachment]

 

This is my new low cost dummy load, made with a Caddock thick film non-inductive resistor. This one is 50 ohms at 1%, and rated at 100 watts, and costs about $11.00 from Mouser or Digikey. I realize the current heat sink will not be adequate for 100 watts, but it will suffice for the 5 and 50 watt calibrations of my K3, it does get warm to the touch. Only problem is resistance measures 51.2 ohms. What value of a parallel resistor would bring that down to 50 ohms? I calculate 1234.56 ohms or 1.2 K. Is that right? Also what would the power rating of the resistor need to be? Thanks.

Darryl, KK5IB


Re: Low Cost Dummy Load

John Lonigro
 

I could be wrong, but I don't think a 1% resistor necessarily means the value is within +/- 1%.  I think there are some statistics involved which might say, for example, that the standard deviation is 1%, meaning there are about 40% of the resistors in a particular lot that would fall outside the 1% value and a few percent even falling outside the 2% value.

And, of course, David is right that the error (or at least some of the error) could be coming from the measuring device itself.  As they say, if you have one clock, you know what time it is.  If you have multiple clocks, you have no idea...

72,
John AA0VE


On 05/11/2015 02:20 PM, David Martin davemrtn@... [4sqrp] wrote:
 

Yes but, as you can see from his photo, he paid for a 1% resistor !!

For $11 (+ shipping), I would be calling the vendor.

OR MAYBE, the error is in the device he is using to measure the resistance ??


On 5/11/2015 2:05 PM, Wayne Dillon wayne.dillon@... [4sqrp] wrote:
 
Hi Darryl
Should be 2K2, this equates to 50.0355 Ohms total effective resistance. Not sure on power as the 51.2 is only about 3% of the 2K2. Anyway why worry about the error? the error is less that 3% and that's better than most commercial dummy loads.
Just my $0.02 worth.
Be blessed
Wayne - KC0PMH

On Mon, May 11, 2015 at 1:49 PM, kk5ib01@... [4sqrp] <4sqrp@...> wrote:
 

This is my new low cost dummy load, made with a Caddock thick film non-inductive resistor. This one is 50 ohms at 1%, and rated at 100 watts, and costs about $11.00 from Mouser or Digikey. I realize the current heat sink will not be adequate for 100 watts, but it will suffice for the 5 and 50 watt calibrations of my K3, it does get warm to the touch. Only problem is resistance measures 51.2 ohms. What value of a parallel resistor would bring that down to 50 ohms? I calculate 1234.56 ohms or 1.2 K. Is that right? Also what would the power rating of the resistor need to be? Thanks.

Darryl, KK5IB




--
http://www.qsl.net/kc0pmh/   Under construction but please visit anyway.
 
QRP -  EFFICIENCY AND SKILL, NOT POWER. 
 
I'm British by birth but American by CHOICE!

Jesus came to pay a debt He didn't owe because we owe a debt we cannot pay...

The Lord bless you and keep you
The Lord make His face shine upon you, and be gracious unto you
The Lord lift up his contenance upon you and give you peace.

God Bless from Wayne Dillon - KC0PMH

Joshua 24:14-15
2 Cor 5:17
1 Jn 2:17
 
Membership Chairman - 4SQRP Group
4SQRP #95
FISTS 17184
FPQRP #342 (Flying Pigs QRP Club)
NAQCC # 0759
QRP-ARCI #11505
SKCC #1155T
CW Ragchewers Anonymous #40
SOC #848
30MDG#1176
NEQRP #693
GORC #192
DMC (Digital Modes Club) # 06686

-- 
David Martin - K5DCM
Mountain Home, Ar.
-+-+-+-+-+-+-+-+-+-+-
"It's only "work" if you'd rather be doing something else" - Dean Kamen


Re: Low Cost Dummy Load [1 Attachment]

Don Wilhelm <w3fpr@...>
 

Darryl,

I would definitely mount it on a larger heatsink.  Do you have a heatsink from an old computer?  That is one no-cost source of heatsinks.  If you do not have one, you may want to ask at one of the computer repair places.

Those Caddock Thick Film Resistors are good for dummy loads, but do not exceed their ratings - they can die a quick death.

73,
Don W3FPR

On 5/11/2015 2:49 PM, kk5ib01@... [4sqrp] wrote:
 

This is my new low cost dummy load, made with a Caddock thick film non-inductive resistor. This one is 50 ohms at 1%, and rated at 100 watts, and costs about $11.00 from Mouser or Digikey. I realize the current heat sink will not be adequate for 100 watts, but it will suffice for the 5 and 50 watt calibrations of my K3, it does get warm to the touch. Only problem is resistance measures 51.2 ohms. What value of a parallel resistor would bring that down to 50 ohms? I calculate 1234.56 ohms or 1.2 K. Is that right? Also what would the power rating of the resistor need to be? Thanks.

Darryl, KK5IB




Re: SSB?

Michael McEwen
 

If you can, try SSB on 7.285 tonight...7:30 and 8:30 CDT.  This Monday night SSB net has been trying to get off the ground.  I plan to try 8:30 for sure and maybe 7:30 if we are finished with supper.

_ _ ...   .. _ _ _

Doc K5OSA - QTH: EM04sr
ARRL  
4SQRP #801 - NAQCC #7625 - SKCC #10098
FISTS #17157 - OMISS #9886
LFSARC (Lawton/Fort Sill Amateur Radio Club)

Michael T McEwen
Lt Col, US Army, Ret

Cellular Phone:  580 919-9205
Residence:  580 529-3412


On Mon, May 11, 2015 at 7:14 AM, Wayne Dillon wayne.dillon@... [4sqrp] <4sqrp@...> wrote:
 

I'll see if I can persuade my antenna on to 17m and then I'll report back (I'll listen out as well).
have a blessed day
Wayne - KC0PMH

--
http://www.qsl.net/kc0pmh/   Under construction but please visit anyway.
 
QRP -  EFFICIENCY AND SKILL, NOT POWER. 
 
I'm British by birth but American by CHOICE!

Jesus came to pay a debt He didn't owe because we owe a debt we cannot pay...

The Lord bless you and keep you
The Lord make His face shine upon you, and be gracious unto you
The Lord lift up his contenance upon you and give you peace.

God Bless from Wayne Dillon - KC0PMH

Joshua 24:14-15
2 Cor 5:17
1 Jn 2:17
 
Membership Chairman - 4SQRP Group
4SQRP #95
FISTS 17184
FPQRP #342 (Flying Pigs QRP Club)
NAQCC # 0759
QRP-ARCI #11505
SKCC #1155T
CW Ragchewers Anonymous #40
SOC #848
30MDG#1176
NEQRP #693
GORC #192
DMC (Digital Modes Club) # 06686



Re: Low Cost Dummy Load [1 Attachment]

Darryl J Kelly
 

Thanks for all the comments, meter is a old Fluke 79 Series II, good meter, can calibrate the lead resistance out, but the meter itself is not guaranteed calibrated. I was just pleased to get a decent dummy load that small, that accurate, and that cheap.
Darryl, KK5IB


Re: Low Cost Dummy Load [1 Attachment]

Chuck Carpenter
 

Darryl,

That's only a half an Ohm tolerance, 50 x .01 = 0.5 plus/minus.

Your meter may not be accurate enough to measure that. The value you measured might be the resistance of the test leads.

You probably don't need to be concerned about that difference.

Chuck Carpenter, W5USJ
EM22cv, Rains Co. TX


Re: Low Cost Dummy Load

davemrtn
 

Yes but, as you can see from his photo, he paid for a 1% resistor !!

For $11 (+ shipping), I would be calling the vendor.

OR MAYBE, the error is in the device he is using to measure the resistance ??


On 5/11/2015 2:05 PM, Wayne Dillon wayne.dillon@... [4sqrp] wrote:
 
Hi Darryl
Should be 2K2, this equates to 50.0355 Ohms total effective resistance. Not sure on power as the 51.2 is only about 3% of the 2K2. Anyway why worry about the error? the error is less that 3% and that's better than most commercial dummy loads.
Just my $0.02 worth.
Be blessed
Wayne - KC0PMH

On Mon, May 11, 2015 at 1:49 PM, kk5ib01@... [4sqrp] <4sqrp@...> wrote:
 

This is my new low cost dummy load, made with a Caddock thick film non-inductive resistor. This one is 50 ohms at 1%, and rated at 100 watts, and costs about $11.00 from Mouser or Digikey. I realize the current heat sink will not be adequate for 100 watts, but it will suffice for the 5 and 50 watt calibrations of my K3, it does get warm to the touch. Only problem is resistance measures 51.2 ohms. What value of a parallel resistor would bring that down to 50 ohms? I calculate 1234.56 ohms or 1.2 K. Is that right? Also what would the power rating of the resistor need to be? Thanks.

Darryl, KK5IB




--
http://www.qsl.net/kc0pmh/   Under construction but please visit anyway.
 
QRP -  EFFICIENCY AND SKILL, NOT POWER. 
 
I'm British by birth but American by CHOICE!

Jesus came to pay a debt He didn't owe because we owe a debt we cannot pay...

The Lord bless you and keep you
The Lord make His face shine upon you, and be gracious unto you
The Lord lift up his contenance upon you and give you peace.

God Bless from Wayne Dillon - KC0PMH

Joshua 24:14-15
2 Cor 5:17
1 Jn 2:17
 
Membership Chairman - 4SQRP Group
4SQRP #95
FISTS 17184
FPQRP #342 (Flying Pigs QRP Club)
NAQCC # 0759
QRP-ARCI #11505
SKCC #1155T
CW Ragchewers Anonymous #40
SOC #848
30MDG#1176
NEQRP #693
GORC #192
DMC (Digital Modes Club) # 06686

-- 
David Martin - K5DCM
Mountain Home, Ar.
-+-+-+-+-+-+-+-+-+-+-
"It's only "work" if you'd rather be doing something else" - Dean Kamen


Re: Low Cost Dummy Load [1 Attachment]

Bill Cromwell
 

Hi Darryl,

Don't even bother about a parallel resistor. Use it as-is. It's barely 2 percent off. How accurate is you DMM? How do you know?

Our solid state radios will work happily into 75 ohm systems. That's a lot more *off* than 1.2 ohms - assuming your DMM is actually that close.

73,

Bill KU8H

On 05/11/2015 02:49 PM, kk5ib01@gmail.com [4sqrp] wrote:

This is my new low cost dummy load, made with a Caddock thick film non-inductive resistor. This one is 50 ohms at 1%, and rated at 100 watts, and costs about $11.00 from Mouser or Digikey. I realize the current heat sink will not be adequate for 100 watts, but it will suffice for the 5 and 50 watt calibrations of my K3, it does get warm to the touch. Only problem is resistance measures 51.2 ohms. What value of a parallel resistor would bring that down to 50 ohms? I calculate 1234.56 ohms or 1.2 K. Is that right? Also what would the power rating of the resistor need to be? Thanks.

Darryl, KK5IB


Re: Low Cost Dummy Load [1 Attachment]

Wayne Dillon
 

Hi Darryl
Should be 2K2, this equates to 50.0355 Ohms total effective resistance. Not sure on power as the 51.2 is only about 3% of the 2K2. Anyway why worry about the error? the error is less that 3% and that's better than most commercial dummy loads.
Just my $0.02 worth.
Be blessed
Wayne - KC0PMH

On Mon, May 11, 2015 at 1:49 PM, kk5ib01@... [4sqrp] <4sqrp@...> wrote:
 

This is my new low cost dummy load, made with a Caddock thick film non-inductive resistor. This one is 50 ohms at 1%, and rated at 100 watts, and costs about $11.00 from Mouser or Digikey. I realize the current heat sink will not be adequate for 100 watts, but it will suffice for the 5 and 50 watt calibrations of my K3, it does get warm to the touch. Only problem is resistance measures 51.2 ohms. What value of a parallel resistor would bring that down to 50 ohms? I calculate 1234.56 ohms or 1.2 K. Is that right? Also what would the power rating of the resistor need to be? Thanks.

Darryl, KK5IB




--
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God Bless from Wayne Dillon - KC0PMH

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Low Cost Dummy Load

Darryl J Kelly
 

This is my new low cost dummy load, made with a Caddock thick film non-inductive resistor. This one is 50 ohms at 1%, and rated at 100 watts, and costs about $11.00 from Mouser or Digikey. I realize the current heat sink will not be adequate for 100 watts, but it will suffice for the 5 and 50 watt calibrations of my K3, it does get warm to the touch. Only problem is resistance measures 51.2 ohms. What value of a parallel resistor would bring that down to 50 ohms? I calculate 1234.56 ohms or 1.2 K. Is that right? Also what would the power rating of the resistor need to be? Thanks.

Darryl, KK5IB


NAQCC MWN

Scotty Long
 

Quick note the NAQCC Midwest MWN Net tonight 40m on or around 7117 kHz at 9pm CDT 0200 UTC...please listen up or down as the frequency may be busy at net time... If we have bad WX I'll unplug...crazy weather and QRN...Thank you for your understanding; have a great week...

40m 7117 kHz 0200 UTC tonight-Monday 9pm CDT

Sent from my iPad

Scotty Long NU0S

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