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The transistors used in the loop amp are PXT2222A. I removed one to do the LF noise test; the result was so noisy I removed a second transistor to make sure somehow I hadn't randomly gotten a bad

I ordered this item from this same eBay Chinese seller and received it about a week ago, and also told Andrew Ikin of Wellbrook about it. After testing it and opening it up and looking at things, in

Just saw this posted in another group.? Expensive junk?

Hi Martin, My real-world tests of the loop amp using a 39" diameter loop located outside with about 2.4-2.5 uH inductance show that transistors with -82 dBm or higher noise output in my tests do not

Hi Steve, My thinking was that maybe any variation in input impedance, when connected to a 'real' loop, could affect the sensitivity on the lower bands, maybe to the same extent as variations in

Hi Martin, My transistor tests do not sweep the circuit or look at input impedance using the VNWA, so no, I don't notice any such variations. Steve

Hi Steve, One thing I noticed when building LZ1AQ's using different transistors, was that the amplifier input impedance varied depending upon the transistor type. From memory the 2N2222's produced low

I have built a couple of LZ1AQ preamps with only BFU590 transistors. Works fine that way too. Tom VE3PSZ

From my understanding you don’t use 5551’s in “ back end” Only the front end transistors have a real effect on noise. See what Steve has been doing with transistors re noise figure. Also see

Just a thought... what about substitung the two 2SC5551 in the backend stage of the LZ1AQ preamp with a couple of BFU590 ? The BFU590 seems to have a greater driving capability of the 2SC5551. After

End of an era for sure. Big bummer.

Wow, that really is sad. Chris When the going gets weird, the weird turn pro - Hunter S. Thompson

Hi Andrew, I have no reason to doubt your findings. But there are differences between the devices, otherwise why to they have different part numbers ? I was just interested to see if Steve's test

Martin, I have measured the LF noise figure using both devices in an ALA1530 and there was no difference. Kind regards Andrew

Hi Andrew, Yes I take your point, but having previous experience of both types in another application (low power VHF transmitter) they do behave differently, so I guess there is a reason they have

Wow, just checked Dan's Small Parts and Kits <http://www.danssmallpartsandkits.net/> page and found he closed shop a few days ago. So sad to see another parts resource go...

Steve and Martin, The noise of the ZTX3866 is the same as the ZTX327. Both transistors basically the same. 73 Andrew? G8LUG

Hi Steve, The ZTX3866 may also be worth testing (if you can get hold of any). Regards, Martin

I looked at the response of different cores and turn numbers using NanoVNA.. -3dB points can be close to 2 decades apart (e.g. 3 and 200MHz). Binocular cores are a bit better in this respect, but

There are two different manufacturers of the PZT2222A (SOT223), ONSemi ( https://www.mouser.de/datasheet/2/308/PZT2222AT1_D-1814579.pdf ) and Nexperia (