开云体育

Although CMRR is an issue, it's not always the overriding factor. Noise is frequently introduced via a poor quality power supply, badly designed bias tee, ground loops, and poor screening of the feed

Thank you sharing your experiences, mike. That fits to my observations, that a transistor with a higher fT is not automatically more prone to oscillation than a transistor with lower fT.? But they

Two different paths for noise ingress, but one common parameter (CMRR) standing in their way?

The curious case when oscillation lowered the operating current :-) The red trace is the stable condition when Idd = 75mA, while the black trace is the unstable condition when Idd = 50mA. The

Thank you Mike for sharing this data point! I have added 1206 inductor footprints on the PCB now. My design files are open at the following

/g/loopantennas/photo/300377/3881224?p=Created%2C%2C%2C20%2C2%2C0%2C0

With the recent talk about oscillation I thought I would share a recent debug. Summary: have multiple ferrite bead types on hand. I made a PCB for the Ikin Norton

For what it's worth, we have found that Vcc to an antenna-mounted preamp (or in our case, the varactor control tuning bias) must be ultra clean. SMPS have no place there. A a GOOD SMPS will have

I've forgotten about the small ferrite bead. You can also pass both the emitter and collector (insulated from eachother) through the same bead. This acts as a common mode choke and forces equal

Just a couple of ideas: SHIELDING: It's not a perfect shielding material, but will illustrate if good shielding would improve things. At any hardware store, you can buy wide "decorative" shiney

Hi Martin Good to hear from you and thanks for the reply. I agree about the shielding from the DC converter and if I had the skills I may possibly try to attempt it myself. Another alternative is to

Well I finally got around to putting something together to test some receiving. I ended up getting the improved LZ1AQ from N4CY. For the loop I took a 4” x 10’ strip of 16oz copper approx 22mils

The general construction is a problem, in addition to trying to get a high impedance tuned loop to operate effectively within a few inches a DC-DC convertor. I suspect that screening some of the

I think Fred's suggestion of an E-Field monopole simulation is still valid. Although the coax may be longer providing a better ground path, the size of the loop providing the antenna element, and its

Hi all, I have been reading with lots of interest the post by AA7U Steve on his findings and modification experiments with his GA-450. Steve, did you find that after doing the modification to power

I agree the two environments will lead to different results. From my reading, there are those are concerned that the long run of coax is picking up indoor interferences which subsequently appears as

I use a Siglent SSA 3021X SA for checking for oscillation. Reading that eevblog thread certainly would lead you to believe the BFU590 is hard to tame and readily prone to oscillation, yet as I've

I've just taken an in-depth engineering purusual of the NXP datasheet for the BFU590Q: 1) For a BJT with an ft of 8.0 GHz, the gain sure drops off rapidly with frequency! They don't even rate gain

QUOTE (from the first link): They don't blow up in an extroadinary fashion, but instead will draw maybe 4x the current (from about 5mA ->20mA) in their failure condition. They also exhibit low gain

Thanks for all the tips, info and help! I have access to TinySA Ultra but I believe monitoring my power supply for unexpected current consumption might work better to detect oscillations. I was