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Whenever I check presmps for whatever purpose, I always assure the input level to the presmp is around -45 dBm. I use the Rigol SA equipmed with the tracking generator. The generator is set to -20

Yes, Tom is correct-- it's entirely possible a second attenuator is needed on the VNA's receiver S21 port to prevent overloading the VNA. The specs of the VNA should state the max S21 input. The

I don't have a microscope, but it would be very useful to have. I have various magnifiers I use on occasion, but a microscope would be much

I use a cheap Chinese copy using plastic lenses, that originally cost around ?8 GBP. It has a second drop down lens behind the first, to further increase the magnification, plus a single swivel

Francesco, I want to say I might be wrong here so, please double check me. In your drawing you show the 20db attn connected to the input of the amp I assume this is to prevent over driving your amp.

Good morning, sorry if I didn't answer all the appreciated replies but yesterday I sat there to do some tests and I have to say that maybe the apparent poor sensitivity on the low ranges of the LN

Not affiliated with them but have used them ever since I was trying to solder and wondered why I couldn't focus close enough. As you age you inevitably run into the issue. The OptiVISOR is one

Coupling capacitor value too small?

I wonder if you might be using BN43-302 instead of BN73-302 material for the cores? A transformer wound on 43 material will have nearly 1/6 the inductance of the same transformer wound on type 73

Hi Francesco, Have you used a nanovna to sweep the gain and input impedance? You'll need a 1:1 input transformer (unbalanced to balanced). You'll also need an attenuator on? the nanovna TX output to

I have built several from the esign in: /g/loopantennas/files/MikeM_Wellbrook_Clone So far two of he 1530 configuration and one of the 100 configuration have been built and tested.

I can't see anything called "Wellbrook_Loops.Kicad_sch" in the files section, can you provide a link ? Regards, Martin

Yes, I understand that, but if it is close to oscillation, due to incorrect transformer phase, the gain can appear to be much higher at mid-frequencies. I have seen this myself with some

Martin, ?His ALA1530LN clone is working on 7 MHz without any problem, but in not working on 2MHz and below.?Everett

Have you got the transformer feedback windings in the correct phase / direction ? It's a 50:50 chance of being the right way around if you build it yourself, don't ask me how I know :-) Have you

I think you may have a oscillation problem that is causing your problem on the lower frequencies. You need to make the board more compact and you need double sided copper shielding on the board. ?I

Good morning, I'm wondering if anyone like me has made a full working Wellbrook 1530 LN amplifier based on the schematic found in the files section named "Wellbrook_Loops.Kicad_sch." with smd 2SK932

Thank you all for your advice and experiments. It looks good, so I was wondering why I hadn't seen it. As for the noise, I am not too worried. in last year I tried a noise generator with zener diode.

I do not see a compelling reason to use 2N5109 for new designs, it is an obsolete part. Central and Microchip terminated the production. The last direct equivalent, the NTE278 is discontinued since

In all these common base preamp circuits it doesn't matter what type of base bias is used--I've seen a LED used in place of a standard 2 cent resistor, so using a 25 cent zener diode is just another