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Can people stop there personal attacks. STOP NOW Dave ,group owner. Dr. David Kirkby, Kirkby Microwave Ltd, drkirkby@... https://www.kirkbymicrowave.co.uk/ Telephone 01621-680100./

They were labeled Styrene, I never found them listed as polystyrene. They are harder to find now than the were 5 years ago. Here's a 3 in styrene pipe coupler,

Mikek, That lathe is only 400 lbs, unless you max it out with accessories. Two big amplifiers would weigh more than the lathe. And it's not that expensive, either. If I needed a lathe, this one or the

Hi Mikek, Attached is representative Q-Curve for constant diameter, 6", and inductance, 240uH, at varying tpi values. As tpi decreases, turn count increases, wire resistance increases, Q decreases.

I hope it can only get better, we had a Horror Fright mini lathe where I worked and it was a pain to work with, to small and had a built in taper among other problems. I'm looking at probably the

Polystyrene or PVC? PVC is known to have issues as an inductor core. REAL air-core inductors don't have coil forms, except maybe little polystyrene stringers (as with Air-Dux) or thin paper, as with

I don't get why Q is going up, losses generally increase faster that XL does, and Q is always lower above about 1MHz than below, (contrawound coils are slight exception) Skin effect and core loss

Hi, No need to be angry about him, Brian. He just opened the door to a new world of pain. Been there, done that. Greater Machines are a hell of their own. With best regards Tam HANNA Enjoy

Hi Mikek, Attached is a representative Q Curve for a 240uH inductor. Blue trace is XL/Rs series resistance wire loss Q Green Trace is Rp/XL parallel resistance core loss Q Red trace is wire and core

Yes, I got wrong, I even referenced the wrong post where the layout form got messed up. Mikek

I have disabled editing of posts because I have found it more of a nuisance than benefit. Sometimes people edit posts to correct a typographical error. Then 100’s or thousands of people get an email

Hello Mike, I suggest you exercise more care in posting personal insults. In most technical circles, it is considered standard practice to label axes. According to the data sent with your first,

That's the right idea. You might want to increase the capacitor by, say, 10x or so to push the corner frequency down further than the 1.6kHz it is with 100pF. I'm looking forward to seeing how it

More like this? Mikek

Your a pretty picky SOB aren't you Brian! I didn't like how that post was when I got done, it had a drawing I thought I'd deleted, and it split my text. I don't like that you can't edit on this group.

Interesting graph, Mike, But it really needs labels on the axes. The ‘observer effect’ goes back to Lord Kelvin around 1860. Who, as a scientist or engineer, relies on anybody’s wiki? If you

You should ac-couple the feedback instead of using that 1k resistor, or else you run the risk of perturbing the bias. You reduce the effectiveness of bootstrapping by reducing its gain, so don't

Here's my slightly educated Proposed Idea of how to do it in the blue (on right side), but, I have other projects to finish before I want to lift my 260A on the bench. I'd be happy to see other ideas

Bootstrapping would certainly boost the shunt resistance at very low frequencies, but there's an inherent grid-cathode conductance that grows quadratically with increasing frequency to spoil the fun

A little more reading and pondering and, I think bootstrapping only helps reduce the loading of the 100MΩ resistor and does nothing for the loading caused by the tube grid itself. On the other hand,