Nice vid Peter! With the HF receiver I'm building I haven't gotten around to building the front end yet and this might make a perfect addition - Thanks! - Cheers, Mark WB8YMV
This is a great invention. Somewhere in the Video I lost trace of what’s with what or without what. But overall: very impressive. I‘m gonna build me one.
Very nice. I have no strong MW stations here in Norway, but this will help me also. What I want to make is a SAW filter selector for the VHF and UHF bands. I got strong Tetra, DAB, 450MHz 4G, signals here. The tetra is ridiculous strong! The filter SMD chips themselves are cheap and have various ranges.
Its not a new invention, its a pre selector - quite a good implementation. I would remove the diodes though, if a signal is strong enough to forward bias them they will introduce harmonics of their own.
Circuit in Peter's video used a 10-300pF variable capacitor. You may be able to get a new polyvaricon variable capacitor such as a 280+280+20+20pF. This should give you a range of 0-300pF with 280+20pF in parallel. You could even connect all x4 in parallel for 0-600pF range. For receive only or QRP (5W or less) on transmit, polyvaricons work just fine.
The frequency list is something you store as a memory. Every location will have a different set of useful frequencies. So you just have to tune around and save what's interesting.
At 14:28 I have the same happening for me as I can see you have too. WHY Is ALL the Band jumping up when the station is sending and Going down when the station is not sending. I KNOW THAT IT IS AM and the signal is suppose to do that. And it is not what i am talking about. It is the hole Spectrum i am tlaking about. I have an RTL-SDR V4. I have A general problem with The front-end is Overloading So it is Clipping the signal and audio By The Way I thunk i Am going to make one Hf Helper 👍👍👍👍
This design is largely no good for the follwing reasons. RF chokes are low q devices wound on Ferrite Here's a typical Mfr's spec on such a device> EPOS 22 μH ±10% Ferrite Leaded Inductor, Max SRF:13MHz, Q:55, 560mA Idc, 740mΩ Rdc, you are wanting and expecting a Q of at least 200 and better 250 in a small signal RF reject circuit a per prosposed . What's being used is a joke for the application. It's sole redeeming feature is it is cheap and pre wound . You need properly selected and wound toroids in this application. There are numerous other faults and I refuse to spend any more time discussing ZL1MZR. PS Better to use the double tuned BPFs from Hans Summers in a relay rack and select the appropriate one via a rotary switch. Might cost a bit more but you pay for performance.
At last, a hardware-optimized software-defined radio.
👍Thanks for sharing Peter. A simple circuit that makes an amazing difference. Suspect this would be good on many AM/HF receivers.
Nice job Peter. Great project, definitely useful. Parts ordered, can't wait to try it. Thanks 73
A few simple components made a big difference to some signals. Thanks for the video Peter.
Nice vid Peter! With the HF receiver I'm building I haven't gotten around to building the front end yet and this might make a perfect addition - Thanks! - Cheers, Mark WB8YMV
This is a great invention. Somewhere in the Video I lost trace of what’s with what or without what. But overall: very impressive. I‘m gonna build me one.
Very nice. I have no strong MW stations here in Norway, but this will help me also.
What I want to make is a SAW filter selector for the VHF and UHF bands. I got strong Tetra, DAB, 450MHz 4G, signals here. The tetra is ridiculous strong! The filter SMD chips themselves are cheap and have various ranges.
What is Tetra?
Very nice, Peter. Thanks for sharing!
Thanks for sharing......very nice.. '73 from the Netherlands
G'day Peter, fantastic!! I'd love that on my new Tecsun s-2200x.. 73's
Very well-done! I have a few radios that could use this treatment. 73
Great Peter, change from seeing you in GQRP, I was looking for ideas to cut out/down broadcast rubbish in my 7mhz DC rx Sprat187. 73 John GM4EIW
clever idea Peter 73
Its not a new invention, its a pre selector - quite a good implementation. I would remove the diodes though, if a signal is strong enough to forward bias them they will introduce harmonics of their own.
What type the antenna?
Be a great front end for a Direct Conversion receiver using an SI5351 for multi band reception
i think this gives the same effect of using a loop antenna with variable capacitor init?
Yes - both are resonant tuned circuits that attenuate out of band signals.
Very good idea. Unfortunally this variable capacitor is very Hard to obtain. I can use a modern one? 73 from PU2PQQ
I’m sure you could use a modern polyvaricon.
Go to the junk yard and find any old radio, it will most likely have all the components you need.
Yes, but the performance won't be as good, and it will have a narrow tuning range.
Circuit in Peter's video used a 10-300pF variable capacitor. You may be able to get a new polyvaricon variable capacitor such as a 280+280+20+20pF. This should give you a range of 0-300pF with 280+20pF in parallel. You could even connect all x4 in parallel for 0-600pF range. For receive only or QRP (5W or less) on transmit, polyvaricons work just fine.
Just hook a Potentiometer in series with a Capacitor Brother ;)
X
👍
Can you share that frequency list for SDRSharp? I have come up empty handed searching for it.
The frequency list is something you store as a memory. Every location will have a different set of useful frequencies. So you just have to tune around and save what's interesting.
Does/can someone make and test these? To sell to folks?
Can modified to receive medium waves only?
Just remove the rotary switch and all the other coils except for the 470uH.
At 14:28 I have the same happening for me as I can see you have too.
WHY Is ALL the Band jumping up when the station is sending and Going down when the station is not sending. I KNOW THAT IT IS AM and the signal is suppose to do that.
And it is not what i am talking about. It is the hole Spectrum i am tlaking about.
I have an RTL-SDR V4. I have A general problem with The front-end is Overloading So it is Clipping the signal and audio
By The Way I thunk i Am going to make one Hf Helper
👍👍👍👍
Why did you skip the station in french?
🤣🤣🤣
All you need to do now is miniaturize this, patenr the dsign, get the Chinese mass producing it for you and watch the dollars roll in! :)
Nothing to patent here. Well known as "preselector" circuit design.
This design is largely no good for the follwing reasons.
RF chokes are low q devices wound on Ferrite
Here's a typical Mfr's spec on such a device>
EPOS 22 μH ±10% Ferrite Leaded Inductor, Max SRF:13MHz, Q:55, 560mA Idc, 740mΩ Rdc,
you are wanting and expecting a Q of at least 200 and better 250 in a small signal RF reject circuit a per prosposed . What's being used is a joke for the application. It's sole redeeming feature is it is cheap and pre wound . You need properly selected and wound toroids in this application.
There are numerous other faults and I refuse to spend any more time discussing
ZL1MZR.
PS
Better to use the double tuned BPFs from Hans Summers in a relay rack and select the appropriate one via a rotary switch. Might cost a bit more but you pay for performance.