RTL SDR HF Helper improves reception

[@Steve-GM0HUU]

👍Thanks for sharing Peter. A simple circuit that makes an amazing difference. Suspect this would be good on many AM/HF receivers.

[@MirlitronOne]

At last, a hardware-optimized software-defined radio.

[@WarrenPostma]

best of both worlds really, since the analog front end selectivity is fixing the digital radio's weaknesses.

[@acestudioscouk-Ace-G0ACE]

A few simple components made a big difference to some signals. Thanks for the video Peter.

[@pasixty6510]

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.

[@Derrick6162]

Nice job Peter. Great project, definitely useful. Parts ordered, can't wait to try it. Thanks 73

[@vincei4252]

Very nice, Peter. Thanks for sharing!

[@ameester1959]

Thanks for sharing......very nice.. '73 from the Netherlands

[@markjacobsen302]

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

[@LordGryllwotth]

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.

[@jankristijan5889]

What is Tetra?

[@bobi_lopataru]

@@jankristijan5889 a type of digital transmission mode

[@Nissan350z33]

G'day Peter, fantastic!! I'd love that on my new Tecsun s-2200x.. 73's

[@Derrick6162]

Am building your antenna design. I hope but doubt the conditions will be as good this year. Hope to hear you on the air here in SE New Mexico. 73.

[@SeAfasia]

clever idea Peter 73

[@W6EL]

Very well-done! I have a few radios that could use this treatment. 73

[@KouroshDelpak]

What type the antenna?

[@davewalker7126]

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.

[@LordGryllwotth]

Can you share that frequency list for SDRSharp? I have come up empty handed searching for it.

[@vk3ye]

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.

[@michaelnoardo3315]

i think this gives the same effect of using a loop antenna with variable capacitor init?

[@vk3ye]

Yes - both are resonant tuned circuits that attenuate out of band signals.

[@testetestando285]

Very good idea. Unfortunally this variable capacitor is very Hard to obtain. I can use a modern one? 73 from PU2PQQ

[@qrplife]

I’m sure you could use a modern polyvaricon.

[@Dreamlgider]

Go to the junk yard and find any old radio, it will most likely have all the components you need.

[@radiorob7543]

Yes, but the performance won't be as good, and it will have a narrow tuning range.

[@Steve-GM0HUU]

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.

[@Electronicstechfundamentals.X]

Just hook a Potentiometer in series with a Capacitor Brother ;) X

[@edbeckerich3737]

Be a great front end for a Direct Conversion receiver using an SI5351 for multi band reception

[@josephmartinelli97]

👍

[@Niels.OZ3NO]

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 👍👍👍👍

[@WarrenPostma]

I think that's why he put an attenuator.

[@AymanAli-vet]

Can modified to receive medium waves only?

[@vk3ye]

Just remove the rotary switch and all the other coils except for the 470uH.

[@Normjohanson]

Does/can someone make and test these? To sell to folks?

[@f1sls]

Why did you skip the station in french? 🤣🤣🤣

[@jemussi7842]

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! :)

[@snail2171]

Nothing to patent here. Well known as "preselector" circuit design.

[@WarrenPostma]

@@snail2171 That being said I'd buy such a preselector, especially as a kit.

[@F_Tim1961]

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.