Ants does exist in every radio receivers regardless of SONY or GRUNDIG whatever it is, see MW ant in the circuit. Other types ants include:

LW ant
SW ant
FM ant
CW,SSB high grade ants..

 

Nike I missed you..

Here's more details about the antenna, tuning cap and RF Choke for complete beginners for a total success

Avoid trimmers if not using a meter dial.

Using a large loop antenna increases the sensitivity much more!
AM Loop Antennas

I've made one same like this using PVC joint frame..visitors asked me whether I've constructed a transformer lol



Construct it and go back to 1960's. Enjoy and Good luck!

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Hi transistor495 thx 4 great effort and i hope the circuit work

I have question 4 u can u tell me what is the benefit of 4148 above the transistor BF494 and where exactly the ED in this circuit.
(SORRY if i ask stupid QUES. iam a beginner )

 

kindaboy,

It's a kinda circuit where the transistor BF494 works on both RF and AF mode at the same time. So is called a 'reflex receiver'. We take benefit by avoiding 1-2 transistor pre amplifier stages where the aim was to make it simplified yet keeping a good level of sensitivity/selectivity and audio quality.

The radio frequency waves caught by the antenna amplified by the transistor and appears at collector, from there 4148 along with 472p cap demodulate it and an audio appears at base of the transistor which is again goes for further amplification along with RF waves. This process repeats and we get amplified RF and AF at collector, which is inputted to the inductor L which acts like an RF Choke. So it blocks high frequency radio waves and only allows passage of audio frequencies through it. 472p at the output of L bypasses any unblocked RF. So we get a clean audio output at C and it is given to the power amplifier for driving a Loud Speaker.

RFC is a tricky part in reflex circuits

 

transistor495

thx soo0oo much 4 ur help

PLZ can u give me just last 2 hints
1) what is 180E ????
2)I want to be communication system designer so any references u
Preferred can help me in my path

And thx a gain 4 ur help

 

180 ohm - I think the 180E maybe Dutch?, as it's used in the Dutch magazine Elektor.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

we generally use R or E to indicate ohms
if they are fractions 3R3 or 0R1 are also used

__________________
Regards,
Sarma.

 

THX alot 4 help

 

'Secrets of RF circuits design' is a good tutorial on this stuff.

 

The original prototype of this circuit is built neatly on an ultra small package, unfortunately I doesn't own it now. However for taking pictures, yesterday I attempted a 1/2hour taken dirty assembly with all components ready in hand.

Only valuable component on the pcb is the audio amplifier IC, which I'll pull out later for other purposes and kick the pcb out.

It works great anyway..

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My another version of MW receiver with an old look. There you can see the strange big remotely tuned loop antenna for DX listening. A worthy construction!

Packed inside my first DMM case which burned out while experimenting with high voltage! I'm proud to give him an extra life through singing and entertaining me

Only use it for hearing to dramas..

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Here's some pics of a MW/SW superheterodyne receiver I built some years before with an odd look . Please note the SW fine tuning lever on the front end.

I think I made it little complicated..

Works great!

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Cn I use bm199 instead of bf494??.............plz help thnx

 

Hello,

If you mean a BF199 then I think they are almost identical HF transistors. Sometimes back I tried for it with no luck(rare?). A few HF transistors might without changing the biasing I guess.