Terry wrote: "ps why do I get a face when I type the number eight? When I edit it it shows an eight. When I hit reply I get a face."
because 8 ) without the extra space is the symbol for that emoticon smile face and the Phorum software reads it that way.. just put a space after the 8 and it will not convert to the face.
8)
Sorry I was unclear I meant pin 5 of the 6A7 (control grid) Measure with - lead on pin6 and the + on pin 5. Should see - a few volts.
Check ur PM box.
Terry
(This post was last modified: 10-02-2015, 06:35 PM by Radioroslyn.)
Quote: When powered up, I get a loud howl through the speaker.
If you have a howl in the speaker, my first question is, are the tube shields in place and tightly grounded to the chassis? Also, is the grid lead to the 75 tube routed on the inside of the tube shield?
Steve
We chatted on the fone and came to the conclusion that it needs to be aligned. Voltages look good but reception is weak. He just got a signal generator but it's not working. More to come...
OK. The newly acquired Heathkit IG-102 RF Signal Generator is now functional. (bad 3K potentiometer) Don't have a frequency counter, except the one on the o-scope, and I can now measure proper frequencies output across the vernier dial. Can also hear the signal on a transistor AM radio.
Don't have a VTVM or a Signal Tracer just yet, but I'm looking into it.
Is there a good thread that describe the test process?
I've located the proper alignment instructions for the radio. Following the instructions, I've been able to hear the tone while connected to the control grid of the 6A7. Was able to max the tone on trimmers 1, 2 and 3. Was also able to adjust the Wave Trap to min. Connection made thru a 220pf cap to the generator.
Now the trouble starts. Signal Generator set at 1400kc, dial at 140, broadcast band, still connected to the antenna. No tone while tuning the HF Oscillator.
Try this... 1400 on the signal generator modulated with the audio tone connected to antenna lug through the 200pf cap. Set radio dial at 140 and then move the dial around until you pick up the tone, maybe at 130 or maybe 150. move the radio dial off the tone slightly but in the direction to move the dial toward 140. Now try tuning the HF Osc trimmer to peak the tone. This moves it closer to 140. Repeat. (this is the rocking procedure they call for at 600 but I've used it at 1400 sometimes) You may run out of trimmer before you get to 140. Just a thought..
That Worked. I can tune 600, but the upper end will now tune around 1300, (with the RF Gen set at 1400). If I tune to 1400 and go back to 600, it's back down around 500, (RF Gen set at 600).
I'm doing this by turning the rear cap (circled in yellow). The directions indicate that I should be rotating the forward cap, (blue). Turning the forward cap does nothing at any frequency.
Gotta be getting close.
I take it, that by hearing these signals through the antenna, through all of the stages, that the radio should be working? Still only receiving one super strong local station out of Boston with lots of static.
>I'm doing this by turning the rear cap (circled in yellow). The directions indicate that I should be rotating the forward cap, (blue). Turning the forward cap does nothing at any frequency.
Yellow one is the osc high frequency adjustment. It is used to set the frequency at the high end of the BCB. Turning cw will low the osc frequency ccw will raise the frequency. Adjust #12 for 600kc on the dial. It's used to set the low end of the BCB. You will probably find that there is a bit of interaction between the two. Just go back and fourth and overshooting one end so when you set the other it falls into alignment
Blue is the antenna trimmer adjust for max signal at 1400kc with the generator connected the ant post, not at 6A7 cap once the osc is on frequency
Be careful some of the trimmer may have HV on them. If you are using a metal 1/4" driver wrap it with a bit of tape and don't touch the chassis while adjusting.
Terry
ps time to go Fibber Mc Gee&molly is on WNAR on line.
(This post was last modified: 10-03-2015, 05:31 PM by Radioroslyn.)
However, with the RF Gen set to 1400, the dial at 1400, I get no audio difference by turning the pot I've circled in blue. I take it this is not done by audio, but via a VTVM?
Still no stations. I guess the antenna coil is still suspect?
Unsolder the wire attached to that trimmer. Measure the resistance from the trimmer to the chassis with the tuning condenser closed. Slowly turn the shaft till it is open with the meter still attached. If good should read open throughout.
