Here is my new project ispired by WD4NKA (regenerodyne receiver for 40m and 80m band).
I use my receiver for 40m and 80m HAM and AM radioband. For 80m I use only one E88CC, for 40m I use two E88CC tubes. (Second tube as oscillator and mixer)
You can use also higher voltage for anode - cca 24...40V, but I use only cca 13V for anode and also for heating. You must use good antenna, I use cca 30m longwire, "unun" and coax cable 50ohm. Setting for good working with 13V anode voltage is not simply! You must use also very good tube for oscillator! (Not all tubes work with 13V anode voltage here!)
And one idea: you can use first tube as preamplifer for 3,5MHz band too, but tube and LC circuit must be shielded! (You must use switch for cathode capacitor 2n2 - for 3,5MHz is grounded! And input LC circuit must be tuned cca from 3, 5MHz to cca 7,5MHz)
You can try also other crystals and bands, but it will be better with higher anode voltage than 13V! If you have ECC86, you can try it also with 13V anode voltage!
Jara "Rat", Czechia, EU