[Amps] Hard bus bar copper and inductor Q

[Roger (K8RI)]

Having wound many coils when I was an Instrument tech, The darker and 
harder strap should be fine.
Hard copper "may" be work hardened copper, an alloy, or both, Copper 
work hardens rapidly and easily. Often soft Copper work hardens so 
easily it becomes a nuisance. Copper can be work hardened by stretching, 
bending, and/or thinning.

"IF" you have the tools, building a coil winder is relatively easy using 
3 rollers, rather than winding the coil on a form.
This approach with modifications can be used for bending pipe, conduit, 
or strap into coils, or circles of many sizes.  There are a number of 
demonstrations on U-Rube.

73, Roger (K8RI)


On 8/31/2017 Thursday 4:48 PM, Conrad PA5Y wrote:
> Hello again, I have gathered almost everything that I need for my 
> 3CX800A7 conversion from 2m to 6m.
>
> I have choice of materials for L1.
>
> I have some 6mm soft copper pipe, some 4mm soft copper pipe and some 
> 3mm silver plated copper wire. All the tubing is C102 copper and forms 
> very nicely. VE7RF suggested that I use some flat strap and make L1 a 
> flat wound coil to reduce capacitance between turns, it is also very 
> easy to drill for blocking caps.  This makes sense to me.
>
> The strap that I have is 17mm wide and 1.5mm thick but I have some 
> concerns. It was used as bus bar material and is much harder than the 
> C102 copper tube that I have. It is also considerably darker in 
> colour. It forms into coils quite easily and is not particularly 
> springy so I am fairly sure that it is not Beryllium copper. I suspect 
> that it has been annealed. I am worried that the resistivity will be 
> high but surely as it was used for busbars it won't be lossy, will it?
>
> Soon I will have a DER EE DE-5000 LCR meter which I am told are very 
> good value for money and I can measure component Q so I should see the 
> difference between the flat bar and the copper tube, if there is a 
> problem. I know for sure that the copper tube is C102 soft copper. I 
> would be interested in hearing from anyone who has this instrument and 
> what they think of it.
>
> Any advice? In the past I have made a number of QRO VHF amps for 6m 
> and without exception the efficiency has been good. This is the first 
> one that I have actually designed myself and I expect the loaded Q to 
> be 10-12, previous amplifiers had big tubes, lots of stray C and had a 
> higher Q and were mainly copies or adaptations of published designs. 
> This time I want to design and truly understand what I am doing.
>
> I am still somewhat mystified by Anode RFCs for VHF amplifiers, I can 
> plug numbers into the GM3SEK spread sheet but I do not know exactly 
> how to design a good choke. Most of the stuff that I found on google 
> was concerned with multi-band HF amplifiers and the perils of series 
> resonance. What are the rules of thumb. I can do the calculations but 
> what are my goals?
>
> Hopefully this will give the reflector a kick and start some 
> interesting discussion.
>
> Regards
>
> Conrad PA5Y
>
>
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps



---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus