Date   

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




--
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


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


K8IQY "Magic Box"

Michael McEwen
 

Anyone have a functioning  K8IQY "Magic Box" to sell?
_ _ ...   .. _ _ _

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


Send in your score

John Lonigro <johnlon@...>
 

I hope the lightning stayed away from your QTH last night, at least long enough to participate in the SSS.  This is Dayton week and a lot of you will be busy packing the next couple of days.  Before you forget, please send me your score, so I can keep the database up to date.  Your submittal is simply your name, call, 4sqrp member number, and number of qualified QSOs.  A "qualified" QSO is one made from 7:00-9:00 pm CDT, using 5 Watts or less, and exchanging call, state, and 4sqrp number/power.  And soapbox comments are always appreciated.  Please send them to secondsundaysprint@....  I hope to get the results out by Wednesday.

In the meantime, I guess I'll start working on this year's certificates for the top operators.  Hard to believe, but there are only 4 more SSS events remaining before I announce the winners.  Where has the time gone?

72,

John, AA0VE
4SQRP Contest Coordinator


Re: SSB?

Wayne Dillon
 

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: Head sets?

Don Wilhelm <w3fpr@...>
 

Doc,

Another headset choice is the Yamaha CM500.  I find it more comfortable than the Heil headset and has a very sensitive electret microphone.  It can be found at Pro Audio sources such as Sweetwater Sound and B&H Photo  The price is usually in the vicinity of $60 which is about 1/3 the cost of the Heil headset.  It is not to be shipped outside the US and Canada for some reason unknown to me, but likely having to do with some trade agreements.

The electret element does need a bias voltage, and it is not clear to me whether the LNR LD-5 is capable of providing bias on the mic AF line.  If it does not, the CM500 has a little 'battery box' that can be used to provide that needed bias.

This microphone is normally used at Pro-audio soundboards as monitor headphones and as a "talkback" mic, so it is not well advertized for ham use.  Try one for SSB and I think you will be satisfied - the audio quality is very good as could be expected from the Pro-audio folks.

My only objection is the extra long cord, I guess made for audio technicians pacing around their soundboard, but a few wraps of the cord secured with a twist tie takes care of the excess length.

73,
Don W3FPR

On 5/10/2015 6:07 PM, Michael McEwen mcewenk5osa@... [4sqrp] wrote:
 
I wish I could use my Heil Pro Set with my LNR LD-5, but the jacks are 1/8" and Heil does not make an adapter for that.
What do you all recommend for a high quality headset that I could use?

_ _ ...   .. _ _ _

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



Re: Head sets?

Don Wilhelm <w3fpr@...>
 

Doc,

I am having trouble understanding your situation.  Pull the Heil Pro Set mic and headphone jacks out of whatever adapter they are now plugged into and you should see that they are 1/8 inch (or 3.5mm) plugs - unless someone has done surgery on your Heil Pro Set.  The ProSet comes native with the 1/8 inch (3.5mm) plugs.

If you are having concerns about the difference between "1/8 inch" and "3.5mm" plugs and jacks, have no fears, they are identical.  More and more manufacturers and distributors are using the 3.5mm designation, but there are some that are 'glued' to the US "English measurement system" that they still refer to them as 1/8 inch.  If you use your calipers, you can convince yourself that there is no difference between the two - if you find any, I believe you can resolve the slight differences by a quick perusal of the manufacturer's tolerances.

73,
Don W3FPR

On 5/10/2015 6:07 PM, Michael McEwen mcewenk5osa@... [4sqrp] wrote:
 
I wish I could use my Heil Pro Set with my LNR LD-5, but the jacks are 1/8" and Heil does not make an adapter for that.
What do you all recommend for a high quality headset that I could use?

_ _ ...   .. _ _ _

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



Head sets?

Michael McEwen
 

I wish I could use my Heil Pro Set with my LNR LD-5, but the jacks are 1/8" and Heil does not make an adapter for that.
What do you all recommend for a high quality headset that I could use?

_ _ ...   .. _ _ _

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: CMOS chips at less than 3V supply?

Don Wilhelm <w3fpr@...>
 

You may find better luck with the 74HC family since it is rated to work from 2 to 6 volts.

One thing to keep in mind is noise immunity.  As the supply voltage decreases, the margin between a valid logic level and the levels in the 'region of uncertainty' also grows smaller.  The result is increased susceptibility to noise that gets onto the circuit wiring.  Not the "noise" as we would hear in our receivers, but "noise" such as RF pickup, the pulses from one part of the logic circuit influencing others as the logic gates switch, as well as hum pickup from magnetic fields of AC transformers.

I do not say that to be a bearer of doom and gloom, but to give you some hints about potential problem sources.  Before concluding your design is sound when working at low voltages, subject the circuit to various sources of external stimuli to make certain it works under adverse conditions - remember, Murphy rules - it will fail when the use of a device is most critical, and when there are the maximum number of folks watching the demo.

73,
Don W3FPR

On 5/10/2015 5:28 PM, mbraner@... [4sqrp] wrote:
 

Well I finally got around to using the experimental method on this.  Using a CD4049 chip (actually an MC14049B), which officially requires a 3-15V supply, set up as an RC oscillator at about 1 KHz, it stopped oscillating when the supply voltage decreased below about 2.74V.  Not good enough for a 2-cell NiMH battery, although good enough for 2 alkaline cells as long as they don't get rather weak.

Now I need to find the gumption to try it with a 74HC series chip.




Re: SSB?

Martin
 

17 works for me.
Martin
K0BXB

On May 10, 2015 4:05 PM, "Michael McEwen mcewenk5osa@... [4sqrp]" <4sqrp@...> wrote:
 

W3FPR suggests that we consider 17M instead of 40M.  I'm a 17M fan so it would be fine with me, but I know not everyone has 17M capability. He is absolutely correct that above 7.200 can be clogged by FBI. PSE reply if you have or don't have 17M.  Let's see what everyone has in mind.

Doc K5OSA

Doc K5OSA

_ _ ...   .. _ _ _

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 Sun, May 10, 2015 at 12:01 PM, Michael McEwen <mcewenk5osa@...> wrote:
Hi, Richard.  Let's see if we get some more takers before we kick off.  Are you living in 2 land or did you move somewhere?

Doc K5OSA

_ _ ...   .. _ _ _

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 Sat, May 9, 2015 at 7:21 PM, Richard Dickerson <richard.dickerson@...> wrote:
I'm game.  When do we start?  I'm retired - most nights are free.

Richard 
WF2F

Sent from my iPad

On May 9, 2015, at 18:12, Michael McEwen mcewenk5osa@... [4sqrp] <4sqrp@...> wrote:

 

Jeremy NQ0M has been trying valiantly to get a Monday night 1930 an 2030 SSB net on 7.285.  I've been able to hear some folks but I haven't been copied.  My experience is that QRP SSB is the most difficult mode.

Being a stubborn old fart, I wanted to see if you all would like to try an additional SSB possiblity.  What about just asking everyone who wants to work SSB to just give a listen for a few minutes every weekday night at 2000 CDT?  Not to be a big deal, but give a quick listen to see if you can copy anyone.  I guess 7.285 is good but if nothing is heard after a few minutes, I'm going to try 275 and 295...less than 10 minutes total unless I get some QSO's.  I know I won't be able to do this every night, but if enough of us are giving it a try, we ought to get some QSO's. If this is not good for you all, I guess it didn't hurt to try suggest the idea.  

If you do this, don't hesitate to call CQ QRP and report any activity on QRPSpots.

Anyone who has another idea, please post.  My first priorrity was CW, next is SSB, and I hope to get on PSK 31 very soon...have the hardware but have not figured it out in terms of hook-up.  I have a Signalinkand will be looking at various info sources...I don't think it will be that hard.  I have Digipan loaded and have monitored 20M with it.

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



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