28-06-2012, 08:57 PM
I tried getting the Regenerodyne up to 10 meters today, started by removing the existing home wound RF coils (the only spare formers I have) and rewinding for a maximum of 30 Mhz with the tuning gang near fully open, their secondaries both ended up with approx 4 turns of .5mm space wound on the 5/8ths formers, both formers were slug tuned.
The primary windings were approx 2 turns of very thin DCC copper wire interwound on the earthy end of the secondaries, I also rewound the tank coil of the harmonic generator to suite.
All put back in the receiver and fired it up.....First thing to note was that I could select the 32nd harmonic from the 1 mhz donor osc ok but it appears to be weak also sweeping a loosly coupled sig gen around that end of the band produced a lot of unselected harmonic products, pretty much as was expected really.
After a quick mod the RF Amp tuned ok at 30 Mhz, with that I decided to use one of the usful properties of the Regenerodyne that is to say the the signal being received can be "got at" by having the osc below the signal frequency as well as above as is normally the custom.
So I selected the 26th harmonic in order to tune from 28 to 29 Mhz with the tunable regen detector in the hope I could pick up some amature transmission but nothing was doing, loosly coupling the sig gen I then swept that band in order to check that everything was working, it seemed to be but sensitivity appeared to be much reduced (did not do any specific tests)
Next I selected the 25th harmonic so I could tune from below and peaked the RF tune for 27/28 Mhz, some signals were received some were CB transmissions, FM I think, there were also a French and a couple of Italian SSB transmissions (USB) that were resolved quite well, sweeping the sig gen through produced quite a lot of unselected harmonic products at 1 Mhz intervals either side of the tuned frequency, diminishing in strength the further away they were, this was also expected as inductance Q's are now taking a dive.
So a conclusion on the above:
Unwanted harmonic frequencies can be a pain but i am taking the view that they will only be a pain in this receiver if they have any other signals to mix with, so on the basis that in general above 22 mhz there is not a lot going on then the chances of a unwanted harmonic interfering with a signal I might be tuned to is reasonably remote and even if it does it will be at a much reduced strength..
So the verdict is I will incorporate a band that covers up to 30 Mhz in the Regenerodyne despite its limitations at such frequencies.
After these tests I removed the RF coils again and rewound them again so I could tune 40 and 20 meters as before,
Secondaries were 9 turns .5mm close wound, primaries 3 turns of fine DCC wire again interwound over the earthy end, the harmonic generator tank was also rewound for the lower bands....bunged 'em in and fired up, I have now an extra band...15 meters, it peaks at about 3 degrees before the end of the RF tuning gangs travel, I checked on the sig gen, these coils now tune from just below 5 Mhz to just above 21.5 Mhz, the eventuall design will have the more normal 3 to 1 tuning ratio.
With 15 meters now available I gave it a go on that band, several European SSB transmissions were received ok.
I was up early this morning so I switched the Regenerodyne on listened to a couple of VK's on 20 meters I love the "sky" effect on the received Australian transmissions quite unmistakable....
Lawrence.
The primary windings were approx 2 turns of very thin DCC copper wire interwound on the earthy end of the secondaries, I also rewound the tank coil of the harmonic generator to suite.
All put back in the receiver and fired it up.....First thing to note was that I could select the 32nd harmonic from the 1 mhz donor osc ok but it appears to be weak also sweeping a loosly coupled sig gen around that end of the band produced a lot of unselected harmonic products, pretty much as was expected really.
After a quick mod the RF Amp tuned ok at 30 Mhz, with that I decided to use one of the usful properties of the Regenerodyne that is to say the the signal being received can be "got at" by having the osc below the signal frequency as well as above as is normally the custom.
So I selected the 26th harmonic in order to tune from 28 to 29 Mhz with the tunable regen detector in the hope I could pick up some amature transmission but nothing was doing, loosly coupling the sig gen I then swept that band in order to check that everything was working, it seemed to be but sensitivity appeared to be much reduced (did not do any specific tests)
Next I selected the 25th harmonic so I could tune from below and peaked the RF tune for 27/28 Mhz, some signals were received some were CB transmissions, FM I think, there were also a French and a couple of Italian SSB transmissions (USB) that were resolved quite well, sweeping the sig gen through produced quite a lot of unselected harmonic products at 1 Mhz intervals either side of the tuned frequency, diminishing in strength the further away they were, this was also expected as inductance Q's are now taking a dive.
So a conclusion on the above:
Unwanted harmonic frequencies can be a pain but i am taking the view that they will only be a pain in this receiver if they have any other signals to mix with, so on the basis that in general above 22 mhz there is not a lot going on then the chances of a unwanted harmonic interfering with a signal I might be tuned to is reasonably remote and even if it does it will be at a much reduced strength..
So the verdict is I will incorporate a band that covers up to 30 Mhz in the Regenerodyne despite its limitations at such frequencies.
After these tests I removed the RF coils again and rewound them again so I could tune 40 and 20 meters as before,
Secondaries were 9 turns .5mm close wound, primaries 3 turns of fine DCC wire again interwound over the earthy end, the harmonic generator tank was also rewound for the lower bands....bunged 'em in and fired up, I have now an extra band...15 meters, it peaks at about 3 degrees before the end of the RF tuning gangs travel, I checked on the sig gen, these coils now tune from just below 5 Mhz to just above 21.5 Mhz, the eventuall design will have the more normal 3 to 1 tuning ratio.
With 15 meters now available I gave it a go on that band, several European SSB transmissions were received ok.
I was up early this morning so I switched the Regenerodyne on listened to a couple of VK's on 20 meters I love the "sky" effect on the received Australian transmissions quite unmistakable....
Lawrence.
