Late 1960's BFO

[jap]

Hi Skippy
-removing T2 from the PCB must with special care in order to not damage .(with not use violence ) taking the time .there the ways to remove the tin easily from PCB,With no damage to the component and PCB.
-(T2)10mm transformer(A critical piece) .
best time.
j.

[jap]

Hi HECTOR
Clear from the drawing that the mistake in each Q1.2,3,4 type EBC. the way to convert - to follow all Q EBC to Each Q EBC And see each item up to the points and so on.
- -What are the specifications of the coil?
- There is an error in connected R20.
-Its clear see my picture V03 .!!
best time.
j.

[HECTOR]

Thanks Jap!
My first guess matched the ebc markings on the trace side of the PCB. They should be true and correct. The speaker connection checks out OK.
I did an impedance test with the stand alone search coil and and there was a 2X voltage gain @950KHZ.
It's a 5 turn, 5"OD paired loop, shielded coil of something like #24 stranded. Just under 1 ohm resistance. I don't have an inductance meter. Any suggestions on a good bargain meter?

[homefire]

Some Info that may help you with that Transformer.

http://g4hup.com/DFS/Rewinding%20Tok...es%20Coils.pdf

[HECTOR]

Found many more errors.
Never thought that I'd make so many mistakes.
No more drinking while working on PCB's

[HECTOR]

Thought it would be good to put these close together.

[Skippy]

That's a bit more like it. Caps C9,C4 will be 1nF, I think. C3 seems a bit high at 10nF, it could be 1nF, worth re-checking it. Not to appear repetitive, R4,R12,R14 need the values correcting.

[jap]

Re again

Found many more errors.
Never thought that I'd make so many mistakes.
No more drinking while working on PCB's

Hi HECTOR
what do you do? - you Do not see my picture V03 !!, i have sacrificed for you all errors in red lines.
Re again --every green lines is true will not touch it again . -all lines & Components in red lines wrong must be re-placed .
-Please draw the coil.
best time.
j.

[Skippy]

Maybe you should post an updated 'error' drawing, jap. Many errors have been corrected now. I can't see any error in the loudspeaker connections?
The pdf on rewinding toko transformers was interesting, but this one on Hectors cct looks like the Toko 10Z / 10EZ series, which are slightly different inside.

[jap]

Hi Skippy
For in the loudspeaker OK,for the rest of the Mis- NOT(all errors in red lines).
I hope that you are comparing picture V03 with your pcb And you will understand.
-What are the specifications of the coil? Please draw the coil.
-For HECTOR modified, I will not put any modification In order for him modified.
-And if there are some mistakes in my modified picture V03 I hope the correction, I do not have pcb.
best time.
j.

[jap]

Hi Skippy
about pdf TOKO 10k thanks to homefire ,T1 the same but pin#2 worked.
-Will rely on measuring ohms between the pins1,2,3 - 4,6 and converted into the number of tu in case it was do not get it new,with the help of pdf to Find out How to make T1 on the shape of Old.
best time.
j.

[HECTOR]

I don't have an inductance meter to list the search coil specs. I checked the resonant freq with an oscillator hooked up to the open coil, and a scope to monitor voltage gain.
Voltage gain doubled at 950KHZ.
It's a 5 turn, 5"OD paired loop, shielded mono coil of something like #24 stranded. Just under 1 ohm resistance. (about .8 ohm)

The unknown transformer on the PCB is a 5 pin, not 6. I have already removed the part and tested for continuity. With the pins viewed as in my schematic, (starting from top left) there was only a measurable connection between pins 1 & 3. No continuity between any other combination of terminals. (meter set to 20M)
I have listed the operating freq at 662KHZ (which varies greatly from the resonant freq of the open search coil at 950KHZ).
I think that's all the information that I can give at this time.
Note that in my updated schematic, the +9V power trace has been routed correctly.

[jap]

Hi HECTOR
-Thanks,of a clear picture of the COIL.
-What are the measuring of(T2) unknown transformer in ohms between the pins1,2,3 - 4,6 ,,,,,,,5not used......(T2) in free from pcb.
best time.
j.

[Skippy]

Based on the search-coil details, I estimate it has an inductance of 6600nH / 6.6uH. It resonates with caps C9,C10. If C9 were 1nF (can you find out what it is, Hector?) that would give a resonant freq of 1.9MHz, which seems way too high. If C9 were 10nF, the resonant freq. would be 680KHz, which is close to the measured reference oscillator freq of 662KHz, which would actually make sense. However, Hector measured the operating frequency of the detector as 75KHz, so I'm unsure of what frequency anything runs at.
I'm also puzzled by the 10mm transformer connections, surely pins 4 and 2 (and 6) must be joined internally to something?

[HECTOR]

Hi HECTOR
-Thanks,of a clear picture of the COIL.
-What are the measuring of(T2) unknown transformer in ohms between the pins1,2,3 - 4,6 ,,,,,,,5not used......(T2) in free from pcb.
best time.
j.

When I had it removed, I only got continuity between 1 & 3. The resistance was low but I don't remember the #.
I could take it out again. I have very nice soldering/desoldering gear.