[morzh]

I do not have matching pads etc so I am not sure how this thing connects to the tuner.

I am able to see the output RF FM signal on the scope.
I use 50 Ohm BNC cable and 50 Ohm scope input.

The frequency seems right.

Without proper loads I am not sure if the signal is right.

Photo later, soon as I fire up my old P4 desktop.

   
   
   
   
   

[morzh]

The last one.

   

As you could see the frequency matches well to the settings.

[Warren]

nice generator. scope too

[BrendaAnnD]

Waveform looks badly distorted to me. Appears you have your scope set to 50 ohm input impedance, so that should close to a proper load. Not sure where I would look for the nonlinearity. Both of my gennys have nice sine wave outputs (unfortunately my expensive HP genny decided to lose something, so the output is way down on most frequencies now. )

[morzh]

Brenda

Yes, FM is that way. The rest of them, FM/AM IF and AM RF are fully sinewave.

The scope impedance (I used both hi-Z probe 10MOhm and straight coax to 50 Ohm) in fact did not change the wave shape much.

What I was wondering is if anyone has a similar Sencore and could look at the wave shape.

----






Warren

No, actually the scope is not that great. It is a digital, it is the very first digital scope I worked with (exact same model) and i bought it as it is good enough for me and was $200 in fully working shape, but its 500 MHz claim is a bit artificial, it is a sampling scope with the sampling rate of 20 Mbit/sec so even though the front bandwidth is 500MHz, it only can show a repetitive signal of such a frequency, otherwise for single events it is good for up to 20MHz (or actually even to 10MHz if you go strict Nyquist here).

[morzh]

BTW here's the thread where they also complain about

1) weak FM signal
2) brittle tuning shaft

I had to glue the shaft - this was the reason for it not working, the shaft was snapped in the middle. JB Weld remedied it so far.


And the discussion here warns of weak signal. (so counters do not see it well).

http://antiqueradios.com/forums/viewtopi...6&start=60

[morzh]

Also from here:


http://www.antiqueradios.com/forums/view...0&start=20

I can say of the SG-165:

-AM RF Gen great 525-1625 Khz is - Great
-AM IF's Gen (455 & 262Khz +/- 25 KHz) - Great
-FM RF Gen 86-110 Mhz, weak, noise, no modulation or MPX sub-carrier - Limited/Fair
-FM IF (10.7 LC gen, 10.7 Mhz crystal) Great
-FM Sweep + 10.7 Mhz + 100 Khz comb markers - Excellent!
-FM MPX 19 Khz with 400 Khz modulation (L and R selectable
.......separately & modulation either 5% or 10%, MPX signal only not on RF - Limited/Good
.......w/ FM RF signal.. Good but limited
-FM 67 Khz SCA signal... Not sure nut wave form looks OK
-Speaker Meters - Dual audio power meters with selectable - Great
........impedance, good for stereo separation of AM alignment peak - Great


The two big limitations is the FM (85-110Mhz) signal is unmodulated and noisy. Also the FM signal does not carry the MPX pilot 19 Khz signal.... The MPX signal is a stand alone signal for direct injection into the multiplex decoder of the stereo receiver. That may be very useful.

From a scope session last night it does not produce MPX signal on-top of the 88-108 Mhz from what I see (could be wrong). From what I read in the manual the MPX or SCA signals are for direct injection into the Multiplex decoder.

Many radios call for the RF to be injected at the antenna with the sub-carriers. Of course there are workarounds. So can the SG-165 be used for stereo? Sure is can do something, but not all radios. Also if you want more precision something that cost more is needed. Has anyone used one for a stereo alignment? What radio and how did you use it.


-----------------------------


Also some pictures there, the signal looks sinewave though pics are low res and I wish they took at higher sweep frequency Mhz/div and better V/div

[morzh]

Well, question answered - a guy from ARF simulated the oscillator for me.

http://antiqueradios.com/forums/viewtopi...7#p2142687

So, I think the Sencore is just fine.

[Ron Ramirez]

Reviving a sort of old thread...

Let me say that the SG165 in question here belongs to me. Mike (Morzh) was kind enough to go through it for me back in the summer.

If I happen to find any more 38-12 or similar Philcos, I will be keeping him in mind for one for certain.

Anyway, in the past week or so, I have used the FM IF section to align the IF strip of a Fisher 440-T, and the AM IF section to align a Philco 41-246. Both work just fine. I also tried the AM RF section on the 41-246 and it is also working well. I have yet to try out the FM RF section...I really should get the 440-T back out and try the FM RF section on it.

Many thanks to Mike for helping an old man out!

[morzh]

Any time, Ron.