Haven't run into any NB that uses crystals in the design but I haven't seen every possibility either.
It sounds like a crystal filter of some sort and maybe the NB sliding lever puts it in circuit or bypass.
Just a thought.
Great radio for SSB, not so good for CW or AM. It's a honey and I love the sound of it.
The filters in that radio are asymmetrical with a steep cut-off towards the carrier and a more gradual slope away from the carrier, giving really nice audio. There's a description and plots in the manual. Have fun with it!
In case you haven't discovered this feature of Drake stuff...the coils have LV on the slugs of the coils. Use an insulated tuning too.
Took me 3 or 4 encounters with LV before I got smart about this one! Zap!
Yup, the older rigs needed some very heavy duty solder irons. I used an old Weller solder gun. Try that today on the SMT stuff and you'll have to buy a new rig.
The solder irons that are available from simple local stores are not up to the task. You may need to order one or maybe find a Weller solder gun at the local hardware store. The folks that have used the Weller guns from the 60's and 70's report the present day guns are not as good.
I got the can cap solder in place. Turned on the power & no smoke . Got static thru the speaker, which is more than I had before. Now to dig around & see what else is going on. Thanks for all of the info & insight.
Just saw a TR4 on EBay with the noise blanker that my TR3 has. It's called a 34-PNB Noise Blanker & it was a factory installed component. Anyone have one of these in thier Drake? Anything special to look out for? I got all the tubes checked & replaced a few resistors. The TR3 is coming along slowly, but it's fun working on it.