Anyone use a 5687 with adapter in place of a 6922/6DJ8/7308/6N23P?
Have a small stash of original 1955 Raytheon 5687 (on contract to Sperry Gyroscopic Company for Us Air Force use) that are legit NOS/NIB. They sounded better than anything else of that tube type that I tried in a pair of monoblocks that I no longer have. Contemplating buying 2 of these adapters and running them in place of the 6N23Ps in a Dodd Battery Powered preamp.
Couldn't find anything on the Forum about this.
Anyone do this? What'd you think?
Thanks for any intel.
At 6.3V heater current for a 6922 tube is 0.3A https://frank.pocnet.net/sheets/049/6/6922.pdf . At 6.3V for a Raytheon 5687 tube heater current is 0.65A https://frank.pocnet.net/sheets/138/5/5687WA.pdf
What is the VA rating of the 6.3V winding of the power transformer in the equipment the Raytheon 5687 will be used in? Care must be taken not to overload the winding causing it fail, burn up/short out. Power transformers can be quite expensive to replace. Also may not be available anymore. |
@jea48 ; thank you for that info. I knew the 5687 had a higher heater current than the 6922, but given that the device I'm contemplating running the adaptered 5687 in is battery powered, it doesn't have a power transformer. I suppose that the relevant question is 'can the battery bank provide sufficient voltage for the 5687 to operate properly?'. I sure don't know. Maybe the even more relevant question is 'given my ignorance of the answer to the other question, should I try it or not?'. A certain Clint Eastwood quote comes to mind... Happy to be further educated, or to receive opinions. |
The preamp uses two 6922, one per channel, albeit only one triode per double triode is used. It's quite remarkable to me that this, what I think is the only audio gain structure of it's kind, generates 16 dB of gain. Regarding Ah; I've gone to LiFePO4 batteries which upped the Ah from "factory" (read: Gary Dodd's shop) 20 (lead acid) to 24. The 4 batteries are housed in the preamp chassis, so I think going any higher in Ah would require an external arrangement...at least with current technology, though this technology is advancing rapidly. The heat, oh yeah, I remember that from amps they used to play in. I'm disinclined to risk a difficult to find and repair piece of gear without some evidence of previous successful traversals of this trail. I was hoping someone here would have experience with this particular modification. I'll stick with experimenting with adaptered versions of the 5670/396a/2C51 family of tubes for which there's an abundance of documented successful traversal. Thank you for your engagement with my question jea48. |
