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 Post subject: Graymark 510 Pt. 2
PostPosted: Feb Sat 07, 2004 9:30 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1218
Location: Charlotte,NC
BC band only, 5 tubes. Flying blind here, no schematic. I do have a few with the same tube lineup (12BE6, 12BA6, 12AV6, 50C5, 35W4), so that is some help. I get alot of static and pick up shortwave on a BC band only radio, The same station several places across the dial. I could not align the IF's or RF. The tuning cap was shorting out in one spot. That has been fixed. I replaced the caps in the IF transformers and can now get a peak before I run out of adjustment (thanks Norm). The oscillator works.<P>I still can't get an RF alignment to work. I still get shortwave several places across the dial. There is still a distinct lack of sensitivty. I can only get reception with the volume up all the way, and my hand on or near the antenna (within an inch). The same goes for the signal generator leads. With the signal generator hooked up, I get that signal several places across the dial also. Some quite close together. Other than the IF transformers, the only adjustments are the 2 trimmers on the tuning cap and an adjustable oscillator(?) coil. Either I'm aligning this thing the wrong way, or something else is wrong. I now see why the guy was smiling when I handed over the $2 at the swap meet.<P>------------------<BR>


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 Post subject: Graymark 510 Pt. 2
PostPosted: Feb Sat 07, 2004 1:05 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 125
Location: La Porte IN 46350
Hi Kent,<P>Most AA5 radios had no adjustment for the oscillator coil. That makes me think someone may have replaced it with a universal coil perhaps designed for a different tuning cap range or maybe someone was trying to convert the radio to short wave. Try listening for the oscillator on another radio. It should be 455kc higher than what the dial reads.<P>Ron<P>------------------<BR>


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 Post subject: Graymark 510 Pt. 2
PostPosted: Feb Sun 08, 2004 1:47 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1586
Location: ayer ,ma usa
Loop may be open/not connected right..it can do strange stuff!!<P>------------------<BR>


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 Post subject: Graymark 510 Pt. 2
PostPosted: Feb Sun 08, 2004 3:19 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1218
Location: Charlotte,NC
Either may be likely, as this was a kit built in a high school shop class. That would explain the maniacal laughter I heard as I walked away with the radio. It was probably his project! Kinda hard (for me) to figure out if the coil is right, so I'll check the loop for continuity.<P>------------------<BR>


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 Post subject: Graymark 510 Pt. 2
PostPosted: Feb Sun 08, 2004 9:58 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1218
Location: Charlotte,NC
Nope, the loop appears to be connected right and is not open.<P>------------------<BR>


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 Post subject: Graymark 510 Pt. 2
PostPosted: Feb Thu 19, 2004 12:54 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1218
Location: Charlotte,NC
Finally got back to this thing. Could this radio have an image frequency response problem (the same station/sig. gen. signal multiple places across the dial, and squeals like a BFO as the dial moves)? I also disconnected the coil to test it for continuity. This is a 3 lug coil and, and no matter which lug I touch with the ohmmeter, I get continuity on the other 2. Could this be the problem? I'm thinking about replacing it. One other thing, I have gotten BC band reception, A station at the low end of the dial, again, several places across the dial along with shortwave at other places 5-6mhz range, mostly on the upper end. No upper end BC band reception, including the local 50kw blaster.<P>------------------<BR>


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