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David Platt, First the input has a L-network coil plus input C of the Jfet. So the input impedance is likely under 2000 ohms maybe 75 ohms. The gray areas on the drawing modules are triple tuned band

Here's a few graphics from the Murata Ceramic filter manual. The first one shows the change in response, both amplitude and group delay, versus impedance load. The next one is Murata's suggested

Right. Small comment: Be careful on layout around the in/out pins on the filter. I can see on your picture you might have quite some capacitance from in/out pins to ground. Normally ground is keept

Dave, Some folks are getting all worked up over the small stuff. Reminds me of what I was taught in the Air Force:? measure with a micrometer, mark with a grease pencil, cut with a chain saw. I

In that respect, after working decades above 50 MHz, 630 and 2200 meters is a relief. Clip leads are not even seen by the RF energy. Dave - W?LEV -- *Dave - W?LEV* *Just Let Darwin Work* *Just

I solved the problem like this.

Aha! Great - I had wondered at the time I read it about the power capacity of the N type. Since I don't have any, though, I wasn't motivated to research it. Glad to know the truth now - thanks. I know

As you say, fiddling with something this complex is unwise; it's said they had to invent a stereo sig-gen good enough to get the lowest distortion and highest stereo separation it could achieve over

Hi John, This matter has already been discussed by those skilled in the art of calibration. What's important is that you can use it in short waves, but you said both 2M and 70cm. Therefore, I would

Newbie question. I run 2 x 10cm sma pigtails from my nano, onto an external frame. They connect to a back to back SMA <> N Socket. My reason for this is I will use the nanovna-f outdoors a lot,

I found a copy of a 1998 Murata databook for these sorts of filters. One set of graphs shows the effect of having source/load impedances which diverge from 330 ohms. Higher impedances seem to create

I've moved the case over to Cults for a paltry donation($2) to help with my time and costs. You can print this in any material you want. TPU is a softer material with a cushion.

I'd very much appreciate postings of the PDFs of the filter data sheets, Bob. A lot of the information on the older parts is getting hard to locate.

I have a few Model 18s and a Model 19 receiver. The Model 19 schematic is Oh, that's a beauty! Individual IF filters tunable inductors and caps - five adjustments per section, each. That really is

I have a few Model 18s and a Model 19 receiver. The Model 19 schematic is attached; note no transformers. What do you make of it? The 18 has a BJT input stage vs. the 19's JFET, and the 18 has no AGC

I have the Murata data sheet here, and for a 180 ceramic filter, your group delay plot looks normal. Murata does not show data beyond +/- 150 kHz, though, and the y axis scale is 1 dB / divison, 6 dB

Thanks, SJ - I rather suspected something of the sort. Something that's certainly going on here, is that the measurement plots are for the test-jig-plus-filter, not just for the filter... I calibrated

Great to hear it works for you! OTG cables, which are typically microUSB, always have pins 4 & 5 connected at the micro plug end. Pin 5 is GND and when 4 is pulled to low on a device that supports

UPDATE Got it working. Looks like the usb-c socket on the nano may be a little sloppy. First, I used the USB Serial Console app and was able to send commands that worked such as "help" and "pause" and

I'm not sure whether this filter was specified to be linear-phase, but I believe that was probably part of its goals. It's an IF filter specified and sold for use in FM stereo tuners. In these