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The BFU590 has an ft of 8.5 GHz. The 2N2222 has an ft of 300 MHz. Chances are highly likely the BFU is oscillating. Try installing a non-inductive 33 or 47 ohm resistor in series with the

Thank you very much, very useful documentation! Ciao F.

Good morning, I wanted to tell you about a problem I'm having with the BFU590s (assuming they are) with which I made a replica of the ALA1530. The one I've used so far has always worked well but it

Good Day Martin, Are we here to discuss philosophical trends or solve some technical-engineering issues ? I guess we are not here to discuss whether the universe was created by G'd or by a single

Ehrenfried! A man after my own heart! ???

Hi Raphael, Apologies in advance, as I once again embrace the role of “philosophical sage”. <sage> It’s basically the very old “Academia vs. Industry” debate. A lot depends upon the

Dunno why the image went missing after the reply was sent. It was visible in the preview. So, I am putting a link the image (

Hi Raphael, Thanks for pointing out flaws that I have overlooked due to writer's tunnel vision. I know reviewing is very time consuming and so thank you from the bottom of my heart for the detailed

Hi Martin, In my profession I always strived for perfection especially when someone wants to publish his work in a magazine by any means… Please take another look of Chin-leong Lim's article

Hi Raphael, I agree there are no strict standards, but most broadband active loops tend to use a loop diameter of approx 1m, an inductance of 2.5uH and a self resonance just above 30MHz. I think

Hi Chin-leong Lim and All, I reviewed your article. What bothers me your conclusion about the equivalent circuitry of untuned unshielded small loop antenna and the proposed schematic diagram of

Hi, I have scanned and uploaded my collection of (historical?) Wellbrook price lists and data sheets from 1999, 2004 and 2007. Hopefully that may help people trying to date the various products and

Placing the transmission line transformer on the input or output makes no difference to the balance. All it does is act as a common mode choke. However on the input side the differential mode

I have considered that, but gave up because the L-network would have to be a balanced / symmetrical? like the one described by Wasserman in reply #19710 & 19720; i.e. two inductors would be required

I think the principle is good. It may be easier to place the transmission line balun on the 50 ohm side of the simulator. I suspect the divergence of the results above 20MHz may be associated with

A very good paper on how to design an active receive antenna. See link: https://www.dst.defence.gov.au/sites/default/files/publications/documents/DST-Group-TR-3522.pdf I have built a similar whip and

Hi all, I have recorded the details of my dummy aerial in this webpage (

Agreed, PA3FWM has done a lot to benefit the community. The other advantage of increasing the plate capacitance, is that the amplifier input impedance can be a lot lower. It doesn't seem sensible to

Thanks for the links. PA3FWM deserves accolades for summarizing this topic for us. Chin-Leong Lim, 9W2LC.

It doesn't have to be a thick tube. Anything that increases the self capacitance is acceptable. https://www.pa3fwm.nl/technotes/tn08b.html Have a look at the "wire cage" in this