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QRPoMeter


Aaron K5ATG
 

I'm building the QRPometer kit and I ran into a minor problem. My kit did not have the C3 capacitor. The C3 cap has a value of 0.001 and has the number 102 stamped on it. In my junk box, I found some caps that have the same value and the 102 stamped on it but it is a little different than the ones that come in the kits.
 
The capacitor on the left is the 102 capacitor that I had in stock. The one on the right is an example of the caps that came in the kit. So I'm wondering if it would be ok for me to use the cap that I found since it has the exact values as the one that is missing in the kit. 
Thank you
'72 
Aaron K5ATG


Lee Bahr
 

Either will work just fine!

Lee, w0vt

On 10/19/2019 9:12 PM, Aaron Scott via Groups.Io wrote:
I'm building the QRPometer kit and I ran into a minor problem. My kit did not have the C3 capacitor. The C3 cap has a value of 0.001 and has the number 102 stamped on it. In my junk box, I found some caps that have the same value and the 102 stamped on it but it is a little different than the ones that come in the kits.
 
The capacitor on the left is the 102 capacitor that I had in stock. The one on the right is an example of the caps that came in the kit. So I'm wondering if it would be ok for me to use the cap that I found since it has the exact values as the one that is missing in the kit. 
Thank you
'72 
Aaron K5ATG


Aaron K5ATG
 

Thanks


Todd Carney <carneytf@...>
 

Just a bit more on these two caps. The one from your junque box (and on the left in your picture) is probably a MLCC (Multi-layer ceramic capacitor). The one on the right in the photo is a "legacy"-type ceramic disk (most likely single layer). Other factors the same, MLCCs are smaller than single-layer caps.

Another important factor with ceramic caps (all caps, really) are the characteristics of the dielectric--the non-conducting material between the "plates" (layers) that form the capacitor. An important characteristic for RF work is the temperature coefficient ("TC"--change in value per degree of temp change) of the dielectric. Whether or not this is important depends on the function of the cap in the circuit. If the cap is being used for RF coupling or bypassing, drift in value due to temperature change is far less important (often totally inconsequential) than a capacitor used in RF frequency-determining parts of an oscillator or filter. Caps with X5R or X7R (the most common general-purpose types) are generally used for coupling and bypassing and for that purpose are made in the higher end of the range of values (for ceramic caps, anyway).

Your 0.001uF cap (and most caps spec'ed in uF) is an example. Caps valued in picofarads (pF)--especially in small values--are usually used in frequency-determining parts of a circuit and their TCs can be critical. For ceramic caps, the NP0 (negative-positive zero) types are far-more stable than the more common X5R and X7R types.

For a really thorough and well-illustrated (but still accessible) article on ceramic capacitors, see https://en.wikipedia.org/wiki/Ceramic_capacitor. It's really quite fascinating (but I'm a nerd, so . . . )

K7TFC_sig.JPG



On Sat, Oct 19, 2019 at 7:12 PM Aaron Scott via Groups.Io <k5atg=yahoo.com@groups.io> wrote:
I'm building the QRPometer kit and I ran into a minor problem. My kit did not have the C3 capacitor. The C3 cap has a value of 0.001 and has the number 102 stamped on it. In my junk box, I found some caps that have the same value and the 102 stamped on it but it is a little different than the ones that come in the kits.
 
The capacitor on the left is the 102 capacitor that I had in stock. The one on the right is an example of the caps that came in the kit. So I'm wondering if it would be ok for me to use the cap that I found since it has the exact values as the one that is missing in the kit. 
Thank you
'72 
Aaron K5ATG


KB9BVN - <kb9bvn@...>
 

I think I found it....google search for Qrpometer Docs came up with this  http://www.4sqrp.com/kits/QRPometer/qrpometermanualv4.pdf

From 2012....C3 is listed as .001 and marked as 102.

He may be using an old doc?  Or maybe he has an old kit?



On Sun, Oct 20, 2019 at 8:04 PM nm0s_qrp via Groups.Io <ai9e_qrp=yahoo.com@groups.io> wrote:
Where are you getting that C3 has a value of 0.001 uF?  None of the documentation has this value.  In the instruction sheet parts list, assembly instructions, and schematic, the value of 0.1 uF is specified.  Please follow the instructions, and use the correct value.

73 Dave NM0S



--
73 de KB9BVN
Brian Murrey


nm0s_qrp <ai9e_qrp@...>
 

So the important question is, do you have a new (NM0S) kit, or an old (4SQRP) kit?  The 4SQRP kits came with RCA connectors.  The old kit used ceramic monolithic capacitors, and included an 0.001u for C3, while the new kits use ceramic disks, and C3 is 0.1u.  The instructions are very different between the two versions.


Aaron K5ATG
 

I bought the kit at the 2019 OzarkCon in Branson. It has BNC connectors instead of RCA connectors.


nm0s_qrp <ai9e_qrp@...>
 

Please use the instructions that came with the kit.  There were major improvements to the kit design about 3 years ago, and the new revision has a lot of different parts.


Dale Hardin
 
Edited

I built the 4sqrp kit.  What are the improvements?  
--
Dale Hardin, KS4NS
Elberta, AL


Dale Hardin
 

And, can my unit be upgraded?
--
Dale Hardin, KS4NS
Elberta, AL


nm0s_qrp <ai9e_qrp@...>
 

The new kit is more accurate, has a full enclosure, BNC connectors, and works to 15W of power.  The old circuit can be modified by swapping out some resistors, and a few other modifications.


Dale Hardin
 
Edited

Please let me know how to upgrade mine.  Thanks
--
Dale Hardin, KS4NS
Elberta, AL


Aaron K5ATG
 

I can't find the instructions that came with the kit. Is there a place where I can get them? 
Are the instructions linked above by Brian KB9BVN the updated ones? 


KB9BVN - <kb9bvn@...>
 

The ones I linked to were from 2012 and are for the QRPometer that 4States sold back then.  They are not current for the new kits that Dave NM0S offers.

On 10/24/2019 4:23 PM, Aaron K5ATG via Groups.Io wrote:
I can't find the instructions that came with the kit. Is there a place where I can get them?
Are the instructions linked above by Brian KB9BVN the updated ones?


Aaron K5ATG
 

I found the updated instructions. If anyone needs them I can scan them and send them to you.