Managed to get the new laptop all workie workie:
The attached image gives details for the prototype Regenerodyne to date, there will be more additions as and when, probably an RF amp and Local Osc. and a single envelope AF amp & Output stage.
The diagram gives details of the coil winding for a tunable IF of 2.95 to 3.55 mhz.
Not shown on the diagram is a 15 pf variable (fine tune) across the 300 pf regen tuning capacitor.
The HT used was 200 volts, you can use more or less but the potential divider values of R8 & R9 might need to be altered in order to maintain the regeneration action over the full 600 khz tuning range.
Final observations on the circuit as shown:
Tested from MW up to and including the 18 mhz amature band.
Full regen available over the full 600khz.
Regen action is smooth (no plops)
Regen osc stability is very good (checked against Shannon Volmet over a 1 hr period)
Regen tuning rate remains unchanged which ever band is selected (as was expected)
No pulling of the regen when altering the RF tuning.
No pulling of the regen when going in and out of full regen.
+ / - 20 % variation of the HT supply made no significant differnce to the regen osc frequency stability.
Very strong signals can overload the regen det (as they do) so some form of RF attenuation will be needed in the aerial input.
The upper tuning range of the regen det coincides with the lower end of the 80 meter amature band, I thought this might be a problem when tuning the RF input to the mixer for that part of the band and to a certain extent it was, regen det oscillation was breaking through but did not present to much of a problem as offsetting the RF tuning slightly to the higher side did not have to much effect on the signals being received, tuning the regen det further up the band increases the seperation and reduces the effect of regen det osc breakthrough.
Local osc injection source for testing was an Avo CT 378A signal generator, output attenuators set to give 25 mv output.
The gen. is set to Fs + IF, eg: for 7 mhz amature band the gen. is set to 10.5 mhz the regen det (2.95 to 3.55) will then tune from 6.95 to 7.55 mhz the image frequency range at this setting is 13.45 to 14.05 mhz, ie: 2 x IF above Fs.
L4 should be wound with tinned copper wire to facilitate ease of connection and fine tuning of the cathode tap, L3 is enameled coated copper wire.
C20 is not a misprint, it is 4.7 pf.
(C8 A) is fitted and C10 should be omitted...that's my drawing mistake.....
For testing and evaluation purposes L1 & L2 were any old aerial/RF tuning coils I had hanging around.
If using a 6AC7 then note that it has a greedy heater.
Lawrence.
The attached image gives details for the prototype Regenerodyne to date, there will be more additions as and when, probably an RF amp and Local Osc. and a single envelope AF amp & Output stage.
The diagram gives details of the coil winding for a tunable IF of 2.95 to 3.55 mhz.
Not shown on the diagram is a 15 pf variable (fine tune) across the 300 pf regen tuning capacitor.
The HT used was 200 volts, you can use more or less but the potential divider values of R8 & R9 might need to be altered in order to maintain the regeneration action over the full 600 khz tuning range.
Final observations on the circuit as shown:
Tested from MW up to and including the 18 mhz amature band.
Full regen available over the full 600khz.
Regen action is smooth (no plops)
Regen osc stability is very good (checked against Shannon Volmet over a 1 hr period)
Regen tuning rate remains unchanged which ever band is selected (as was expected)
No pulling of the regen when altering the RF tuning.
No pulling of the regen when going in and out of full regen.
+ / - 20 % variation of the HT supply made no significant differnce to the regen osc frequency stability.
Very strong signals can overload the regen det (as they do) so some form of RF attenuation will be needed in the aerial input.
The upper tuning range of the regen det coincides with the lower end of the 80 meter amature band, I thought this might be a problem when tuning the RF input to the mixer for that part of the band and to a certain extent it was, regen det oscillation was breaking through but did not present to much of a problem as offsetting the RF tuning slightly to the higher side did not have to much effect on the signals being received, tuning the regen det further up the band increases the seperation and reduces the effect of regen det osc breakthrough.
Local osc injection source for testing was an Avo CT 378A signal generator, output attenuators set to give 25 mv output.
The gen. is set to Fs + IF, eg: for 7 mhz amature band the gen. is set to 10.5 mhz the regen det (2.95 to 3.55) will then tune from 6.95 to 7.55 mhz the image frequency range at this setting is 13.45 to 14.05 mhz, ie: 2 x IF above Fs.
L4 should be wound with tinned copper wire to facilitate ease of connection and fine tuning of the cathode tap, L3 is enameled coated copper wire.
C20 is not a misprint, it is 4.7 pf.
(C8 A) is fitted and C10 should be omitted...that's my drawing mistake.....
For testing and evaluation purposes L1 & L2 were any old aerial/RF tuning coils I had hanging around.
If using a 6AC7 then note that it has a greedy heater.
Lawrence.
