Ok! I have tried with 90vac and rectifier on place, switch on and nothing made smoke checking the tubes all filaments are normal, 5Y4 is hot but less than first try and now I can see a small glow in what I think are the filaments in both sides of the black "shields" inside the glass(first try nothing), checked the voltage in #56 and is arround 250vdc, the schematics say something arround 330vdc I will try later to go full voltage and I will tell here the results. Thanks again for the help to get back to life this radio!
Checked voltages in ecap and is arround 310vdc, checked also underneath the reachable tube sockets and 6k7g where is says I think 90? And 270vdc I got 78vdc and 250vdc at full voltage in variac (110vac) any way I can check sound output without speaker working (no cone)?
I forgot to tell that at 110v the radio get 0,45amps
Thanks
(This post was last modified: 04-10-2018, 07:43 AM by Jeepeto.)
If your voice coil is missing connect a pm spkr across the secondary of the output transformer. If the original coil is still connected remove it from the circuit.
At 110vac your a little low should be up around 115-120vac. If you want to be precise about it hook your ac volt meter across the 6.3v heater line and use you variac to set the heater voltage to 6.3v.
With 250 and 78vdc I would think it should work, I seems to be high enough to get the electrons to flow. Do you have access to a signal generator??
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Yes, is a heathkit sg-8 but I need to change I think the electrolityc cap before use it, I bought it as working but not sure will...I must check it and maybe I have to do a restoration inside a other restoration I will install the pm speaker as you said after work with 115-120vac to the radio to check again voltages and will check the signal generator too, really I apreciare the help and support.
One question off topic, I got for free a static transformer 700w from 28vdc to 115vac 400hz, could be used for make something useful or just for test avionics or aircraft equipment?
Cheers
Can't think of too many things to use a 400cy transformer. Won't work on 60cy just get hot and burn up.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Well then, was free, I will make a good paper weight or use the refrigerated box to make a diy proyect... Now on trails again I got some time to test with real full voltage 115vac, and 6,3v on heaters, connected an old car speaker coaxial to the secondary, AM and after 30sec warming it started to sound an station! I raised the volume almost full but was like 30% in volume, mention that I have no antenna installed, but just by getting close my hand to the green wire comming from the tunning cap to the top of the 6A8G det-osc the volume raised a lot. Now I know is working I will try to do the alignment with the heathkit after check it, I received also today the new cone, is one I found in italy since the shop in USA does not ship overseas, was arround 10€, not cheap but this one is paper reinforced with cloth and look almost the same as the old and fit almost perfect, just little trimming on sides to get inside (is 8") maybe is little more rigid than the old...I will post Photos later.
Thank you Terry for the help, I am very happy to have it working, was in very bad shape when I picked it in Charlotte NC. And now is comming to life little by little, I think I will continue with the hobby of this old tube radios and studying how to repair, I like it a lot
(This post was last modified: 04-11-2018, 10:34 AM by Jeepeto.)
On the SG-8 it's entry level generator and the frequency calibration is suspect. There is only one adjustment to calibrate it it effects all 5 bands. You might be able to get 1 band close but that's about it. Would recommend that you use a modern digital receiver to check the generator frequency. If your receiver only covers the mw range you can listen for the 2nd harmonic to set the generator to align the IF. In more simple terms tune the digital receiver to 940kc (470kc x 2 = 2nd harmonic) and listen for the generator's signal tuning it near 470kc on the dial. Use that setting to align the IF stage.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
I have 1 digital radio somewhere, I will follow your instructions to get it working, I will post the results later.
Here are the pictures of the speaker trimmed
The only place that I can think of where they would use 400 cycle AC is on an aircraft, but it's usually 120 volts. I would keep the transformer around though, you could try building a DC to DC converter out of it is the primary is center tapped.
Regards
Arran
I do not know if this is the correct place to ask since is a general question not relationed with the radio, is something that surprised me with the SG heathkit: almost all ceramic capacitors (more than 10) are far away from its values, I though ceramics are more reliable and dont fail as silver mica, is it normal? By the way, speaker is finish
I'm a little surprised as ceramic caps usually pretty good in terms of tolerance with that being said the only caps that are critical are the 10, 33 and 150mmfd caps. The others not so much unless they are + or - several times their value.
If they are not electrically leaky I would leave them. Probably not going to notice much of a difference in performance. Would add a .001mfd cap between the bandswitch and and rf output to isolate any dc voltage it may come in contact with.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
checking the tubes all filaments are normal, 5Y4 is hot but less than first try and now I can see a small glow in what I think are the filaments in both sides of the black "shields" inside the glass(first try nothing), checked the voltage in #56 and is arround 250vdc, the schematics say something arround 330vdc I will try later to go full voltage and I will tell here the results. Thanks again for the help to get back to life this radio!
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