On 17 Jan 2025, at 16:06, Reginald Beardsley via groups.io <pulaskite@...> wrote:

?

Miguel,

Most welcome. Be careful about who you buy a nanoVNA from as there are lots of bad copies. The H4 has the advantage you can load time-frequency FW to it, though not both at the same time.

It would be very hard to find a damage level for an internal test point like that. The 1 V at 50 ohms for the signal generator source is as close as you get. I did not insert attenuators. Strictly I should have, but I was only showing the basic setup and forgot. Not good! However, I also know from experience that the output signal is quite low.

I just measured the default output of my H4 using a 50 ohm thru and DSO at 7.4 mW or 8.7 dBm. I did not find a way to set the output power on the nanoVNA H4.

I also strongly recommend Erik's tinySA. I have several as I use them for signal sources in addition to the SA function, though they need suitable LP filters.

FWIW I installed an IEC socket & EMI filter in mine and removed the posts for the factory cable storage setup. Vastly more convenient and it's not so pristine that it mattered.

You mention that you are missing some mechanical parts. I have a machine shop so if it's not too complex a part I can probably make one, though shipping cost might be prohibitive. Get it working properly and I think you'll feel the money was well spent. It's an interesting design of considerable fame.

Likely you will encounter component drift issues. I had to rework the fine tune capacitance to get it where it should be.

The FRG-7 was my first project radio. I also have an FT-101E and TS-520 in queue. A close friend, now SK, carried an FT-101E and FRG-7 on a circumnavigation in a 37' ketch in the '70s. Could not praise the radios highly enough. Four years at sea is a severe test case.

Have Fun!
Reg
W5UHU

On Friday, January 17, 2025 at 04:29:04 AM CST, Miguel Frutos via groups.io <m.frutos@...> wrote:

Thanks Reg,

I will get a NanoVNA as it seems very useful. Just one doubt: where can I see the limits of the signal we can inject in TP103? Don't we need an attenuator in the nano-VNA to protect the radio circuit?

- Miguel

El vie, 17 ene 2025 a las 2:21, Reginald Beardsley via (<pulaskite=[email protected]>) escribió:

Here is my H4 hooked up with CH0 connected to TP103 and TP102 and CH1 connected to TP104 and TP105 per the manual.? SMA-M/BNC-F adapters and BNC-M to alligator clips.? One can do rather better with a custom cable set at the radio end.

I didn't make any effort to set the nanoVNA properly with a thru cal, etc.? It should be done for alignment, but not needed for just a demo.

Have Fun!
Reg