- This topic has 4 replies, 3 voices, and was last updated 1 month ago by mwpeters75.
April 29, 2020 at 15:40 #8593Guenni75Moderator
Here is the ultimate superhet with some extensions which can be used by experienced SW listeners. Some connections are prepared for the s-meter (quality: 1…5) and the “BFO” to receive (and understand…) SSB like the Braun T1000 station solution was realized.
First the three IF stages (in a block-saving manner) with the AGC line going through all blocks, the s-meter connections and the bfo interface (an additional block with the switch/pot/osc, please refer to T1000):
Sorry for the German remarks – I first built it for 2 fellow radio collectors in Switzerland – now these blocks are back, and together with some other blocks here is the complete receiver:
A frequency meter can be connected at point “f”. This unit should be able to subtract the IF for a correct display (!) – this is an example (special block, thanks to Pius Steiner, CH):
Ideas for using the prepared connections can be found here (Braun T1000, AM IF):
To the right: the special oscillator to shift the 455 kHz to +/- 1 kHz and feed this frequency via 3 pF to the base of the second IF transistor. Varying “mgc” and “bfo” via pots helps making SSB understandable.
Another “quick & dirty” solution is this super simple SW superhet with NE612, here with mono-cap tuning:
There are several solutions, even with 3 variable caps – perhaps I will find some time for another experiments…
Further (and initially as the last development) still follows some SW receivers (no superhets!) with tuning & feedback sensivity control – keep watching!
April 29, 2020 at 16:20 #8594LectronFanModerator
Oh my God ! So many great radio circuits. I’m still in the superheterodyne MW receivers. Short wave and morse code are fond remembrances from the time I listened to an old 3 band tube radio .
Can we put together a working Heterodyne radio for Lectron with some salvaged parts ?
When I see Ll your receivers, I don’t know which one to choose !
April 29, 2020 at 23:06 #8595mwpeters75Keymaster
Thanks very much Günther for these amazing Lectron System adaptations! They go far beyond the little 2 and 3 transistor AM radios that were initially presented by Egger and Braun. Thanks so much!
- This reply was modified 1 month ago by mwpeters75.
April 30, 2020 at 15:56 #8597Guenni75Moderator
I just found a photo from one of my Swiss colleagues working with “my” SW superhet and the special frequency counter (see above):
The “real” frequency is shown, and the second line displays the computed radiowave length in meters (1 meter = 3.28 feet or 39.37 inch 🙂
How to calculate: Speed of Light (in km/s) devided by Frequency (in MHz) results in Radiowave Length (in meters):
299792.458 : 6.0006 = ROUND(49.96) = 50 meters
For those who are not familiar with kilometers: 1 km = 0.6213711 miles (US and UK)
And: yes – we could develop a Lectron superhet, but first let me complete the SW area and then complete the required adjustment process for superhets 🙂
May 2, 2020 at 17:33 #8603mwpeters75Keymaster
Thanks very much Günther!
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