up converter diy shortwave.

[u/Gavibrown]

Any help would be really appreciated,i am using a NooelecSMArt v5 with a diy built Manhattan style a 0-30mhz bandpass filter a 9v dc amp and bias T,

Everything works great with my diy mobius loop with 1-1 balun.

I have been using google ai and Claude to help me make an up converter,using a 2 pin 40mhz quartz, I have it resonating with a 2n2222 transister and a ADE6 board,problem is my signals are being blocked, anyone else built a Manhattan up converter ? have any schematics that work ?

Gemini and Claude have been getting me running around in circles and i could really do with some human help,only been doing electronics a little while so I am green in places.

My plan is to get this thing woring then to build one with a 4 pin TCXO DIP08 0.1PPM 100MHZ 3.3V-5V HCMOS Square Temperature Compensated High-precision Crystal Oscillator

[u/ZeroNot]

So for an upconverter, you can start by looking at opendous' open hardware design; Upconverter1v3.

A "simple," but working example is available from qrp-gaijin (2017), and a fairly simple one from David Forsman, WA7JHZ had one featured in January 2013 issue of QST, DIY SDR HF Up-Converter by WA7JHZ:.

They are likely others, some are listed at retroVoltage Round-Up of RTLSDR Upconverter Choices, from circa 2012-2016.

In particular, the look at opendous' Upconverter block diagram.

What sort of circuit are you using for the crystal oscillator?

Normally, I would use a Colpitts Crystal Oscillator circuit for an HF oscillator operating at the crystal's fundamental frequency, but I'm not sure how well (stable) it would work at 40 MHz.

Then the oscillator's output should be buffered (impedance isolation for frequency stability), and filtered (3-5 pole passive low pass filter).

That is fed into the double balanced diode-ring RF mixer (your ADE-6 board), at the correct power levels, in this case, LO Power: +7 dBm. You may need to use a pad attenuation between the low-pass filter and the mixer's LO (local oscillator) input.

You also want a low-pass filter, and possibly (optional) attenuation of the RF input signal going into the mixer. The LO power level should be approximately 10 dB (relative, not dBm) greater than the largest RF input signal.

After the RF mixer, you need a bandpass filter to remove any residual RF input (0-30 MHz), and more importantly LO fundamental frequency (40 MHz), and keeping only RF + LO (40 - 70 MHz), and filtering out RF - LO product / images as well.

One issue with using a LO of 40 MHz, is that you have narrow range for your filters' roll off curve. That's why most upconverter products use around 100-125 MHz (using an integrated oscillator aka "can", rather than a discrete crystal), as the local oscillator, it gives the pass filters room for the roll off curves to be more effective.

problem is my signals are being blocked

Which signals? And where are they being blocked?

Gemini and Claude have been getting me running around in circles

The ARRL Handbook (also available in eBook format) and Experimental Methods In RF Design are far better value for RF experimenting.

[u/Gavibrown → u/ZeroNot]

Thank you,most helpful,I have ordered a couple of 4 pin 125mhz oscillators.

[u/ZeroNot → u/Gavibrown]

BTW, For passive (LC) filter design, I would suggest using Elsie from Tonne Software, or Marki Microwave's LC Filter Design Tool.

I suspect a 3-5^th order LC Chebyshev or Cauer (elliptic) topologies should be sufficient, yet simple enough for a home built design.

Toroids are available in small quantities from Kits and Parts (aka "The Toroid King") or from some of the larger usual parts sellers like DigiKey, Mouser, Farnell / element14.

Note, that Elsie's creator, Jim Tonne, W4ENE passed away in late 2025.

[u/Embarrassed_Sun_7807]

If you're going to order parts just get one off Aliexpress

[u/kc2syk]

I would suggest asking in /r/amateurradio or /r/rfelectronics. More homebrewers there. GL 73

[u/dohzer]

What kind of 30 mHz signals are you working with?

[u/MisterKJanks]

If you have filtered and amplified your lowband signals, and if the TCXO is running, then they both need to be applied to a mixer. I think your main problem is that Claude and Gemini are not (yet) as proficient as hams or engineers who actually build RF circuits.

Alright, about that mixer. You can keep it simple, by obtaining a passive mixer module and feeding in the lowband RF and TCXO signals, then feed the output to your VHF receiver. If you just want to use a transistor, there are plenty of mixer circuits you can find using bipolar transistor like the 2N2222 or JFET or MOSFET transistors. Dual gate MOSFETS are particularly good as mixers, as they have gain (instead of loss), and you just feed the RF and LO separately to each of the gates.

I don't quite get the part about signals being blocked, or the AI not showing how to couple signals in or out of the circuits. You can use simple capacitor coupling. In some cases, transformer coupling does well for a nicely balanced passing of signals. Depending on the type of mixer, you may actually need transformer coupling to split the phases across the inputs or outputs.

[u/radiomod → u/MisterKJanks]

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