开云体育

Caaarlo, Would you publish as attachments complete s1p files for both amplifier and your loop antenna ? I am planning to check whether an impedance matching network can be synthesized for this

The output transformer is now the limiting factor for 30 MHz high end gain. The 2SC5551 is much less susceptible to UHF oscillation than many other such transistors, though some circuits using it

The ft of the 2SC5551 is 3.5 GHz. This should show absolutely no gain slump at 30 MHz. But,being in the GHz range, it will be far more difficult to "tame". Good ?W layout techniques will be

Look up "gain-bandwidth product".?? This amp has about +25 dB gain. If it had 0 dB gain then it could work at its rated max frequency. 73, Steve AA7U

Ok, I stand corrected, as I was doing things wrong, both maths and sweep: 1-The VNA was being saturated with 10dB above its dynamic range. 2-THe mismatch attenuation calculations were wrong, so the

The ft of the '2222 is 250 to 300 MHz. How could that account for gain slump at 30 MHz? Dave - W?LEV [email protected]> wrote:

The following photos have been uploaded to the Caaarlo LZ1AQ sweep ( /g/loopantennas/album?id=296346 ) photo album of the [email protected] group. *

Thanks to Caaarlo for pointing out my long input lead problem. I've redone the MPS2222 build plus built a second one using 2SC5551. I've deleted the old picture and sweeps from the folder and put new

Ideally, but when using a stand alone VNA, that is not connected to anything, it is so small in terms of wavelength, that it is effectively "floating" and balanced without the need for an extra

Mine is around +23dBm I also tried varying the sweep power, no significant changes noticed up to the maximum level of 0dBm. Regards, Martin

When Sweeping a LZ1AQ amp you need to use a 1:1 transformer between the VNA and the amplifier. You also need to calibrate the VNA on the amp side of the 1:1 transformer. What I use for a 1:1

I'd also suggest -50 or -60 dBm input through the CM to DM transformer. With gain, -30 dBm is a bit much to assure remaining in the linear region. Used as the '2222 are in the amp, I have no idea of

I just found an old LZ1AQ board I prototyped some time ago using MP222A transistors. I connected a 20 dB attenuator on the amplifier output, and made a quick 1-50MHz sweep using a LiteVNA64 and

While replying to steve I realized I might be close to saturating the VNA input. So I will insert an attenuator after LZ1AQ output and see how it goes.

Steve, My setup is simple: The VNA is a NanoVNA, which is a self-powered VNA, hence no ground influence, same goes for the laptop connected to it. *1) I did not use any balun or transformer to

I forgot to add a link to the photo. /g/loopantennas/photo/267767/3804785 Regards, Martin

Hi Steve and Caaarlo, As an aside. If you use the same construction technique as shown in the photo that Caaarlo posted. /g/loopantennas/photo/296346/3804668 Initially cover the

Hi Caaarlo, Thanks for your interesting comments. Please tell me the exact setup and equipment you used to do your own gain measurements, and what input level did you use? Thanks, Steve AA7U

Steve, Thank you for the compliments. I have just measured gain as per your request, and mine is almost flat: 1MHz 33.15dB 7.1MHz 33.51dB 30MHz 33.50dB At 1MHz I am sure that the lower gain is due

I had some MPS2222 transistors and built up a quick LZ1AQ and swept it, with the sweeps and picture of the ugly-build added to the Photos. This is only for comparing? with Caaarlo's build and sweeps