04-09-2023, 07:50 AM
Hi Bob,
I know that you are an expert. You have done some fantastic restos, but the following is important for anyone who does restorations, especially at our age (at least some of us). It is important to be careful handling the mouse stuff. Scoop and brush out while outside and wearing an N95 mask. Wipe as much as possible with 70% Isopropanol, a 1/10 dilution of household bleach or disinfectant cloths, keeping wet those parts that won't be damaged by it, and the interior of the cabinet. The reason for this treatment is to kill off the diseases that mice carry, including "hantavirus". At worse, hantavirus can get you very sick. At best, if you contract and recover from hantavirus, the antibodies will affect certain immunochemistry lab tests, such as tests for therapeutic drug levels that are run on those being treated with digoxin, certain anticonvulsives and certain antibiotics. (Sorry, my previous career as a Lab Tech and Apps Specialist for a BioMed kicked in).
This set uses a "Reflex RF / Audio stage", hence the plate of the first tube going through the primary of an RF and AF transformer. This stage and the Audio Output stage are both supplied by the "B+". The detector is supplied by the +22V "Detector B+. This is similar to my FADA 160, but the 160 is a 4 tube job.
The 2nd tube in the set is a grid leak detector. Per the RCA Receiving tube Manual (Version RC10, 1930), for the grid leak resistor (R16 on your schematic), any resistance between 1 and 5 megohm will work. The higher the resistance the greater the sensitivity. the lower the resistance, the less the distortion and instability. 2 megohm is common. The cap should be 250 pF (0.00025uF). Considering the open frame of the cap, replacement (under the chassis or whatever) may be the best alternative. I say this merely because of the possibility of leakage with an unsealed cap. this cap can also suffer from SMD. I did have one of these short. Heck, that cap is 100 years old.
Now for my $0.02 on the "jumper wire". At 45V on the RF/1st AF and 2nd AF plates, bias is not really needed, however at 90V, the -4.5V bias was needed. It is possible that a radio technician (if an "NRI man", a "Radiotrician") added the jumper permanently to prevent miswiring by the customer, or maybe Crosley installed the jumper, and the instructions to the installer were to cut the jumper if 90V B Battery and 4.5V C Battery were used.
As for a speaker, the sound would be weak (a 01A puts about 0.010W at 90V), but for your purposes, a speaker and output transformer from an AA5 will get you going till you get working headphones or horn. if you have a 112A, that will get you a little more miliwattage. You can also hook up an amp to the secondary of the transformer.
Hope this all helps.
I know that you are an expert. You have done some fantastic restos, but the following is important for anyone who does restorations, especially at our age (at least some of us). It is important to be careful handling the mouse stuff. Scoop and brush out while outside and wearing an N95 mask. Wipe as much as possible with 70% Isopropanol, a 1/10 dilution of household bleach or disinfectant cloths, keeping wet those parts that won't be damaged by it, and the interior of the cabinet. The reason for this treatment is to kill off the diseases that mice carry, including "hantavirus". At worse, hantavirus can get you very sick. At best, if you contract and recover from hantavirus, the antibodies will affect certain immunochemistry lab tests, such as tests for therapeutic drug levels that are run on those being treated with digoxin, certain anticonvulsives and certain antibiotics. (Sorry, my previous career as a Lab Tech and Apps Specialist for a BioMed kicked in).
This set uses a "Reflex RF / Audio stage", hence the plate of the first tube going through the primary of an RF and AF transformer. This stage and the Audio Output stage are both supplied by the "B+". The detector is supplied by the +22V "Detector B+. This is similar to my FADA 160, but the 160 is a 4 tube job.
The 2nd tube in the set is a grid leak detector. Per the RCA Receiving tube Manual (Version RC10, 1930), for the grid leak resistor (R16 on your schematic), any resistance between 1 and 5 megohm will work. The higher the resistance the greater the sensitivity. the lower the resistance, the less the distortion and instability. 2 megohm is common. The cap should be 250 pF (0.00025uF). Considering the open frame of the cap, replacement (under the chassis or whatever) may be the best alternative. I say this merely because of the possibility of leakage with an unsealed cap. this cap can also suffer from SMD. I did have one of these short. Heck, that cap is 100 years old.
Now for my $0.02 on the "jumper wire". At 45V on the RF/1st AF and 2nd AF plates, bias is not really needed, however at 90V, the -4.5V bias was needed. It is possible that a radio technician (if an "NRI man", a "Radiotrician") added the jumper permanently to prevent miswiring by the customer, or maybe Crosley installed the jumper, and the instructions to the installer were to cut the jumper if 90V B Battery and 4.5V C Battery were used.
As for a speaker, the sound would be weak (a 01A puts about 0.010W at 90V), but for your purposes, a speaker and output transformer from an AA5 will get you going till you get working headphones or horn. if you have a 112A, that will get you a little more miliwattage. You can also hook up an amp to the secondary of the transformer.
Hope this all helps.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
Best Regards,
MrFixr55
