1KHz to 33MHz Adjustable Oscillator Module Board

easyrider8 · **Posted:** Apr Thu 12, 2012 2:01 am

Looks like this would be perfect for the AM transmitters.

http://www.ebay.com/itm/1KHz-33MHz-Adju ... 4714wt_982

Flipperhome · **Posted:** Apr Thu 12, 2012 2:21 am

Dave Doughty got one and ran some tests with it in the "Simple VFO for AM Transmitters" thread here
http://www.antiqueradios.com/forums/viewtopic.php?f=12&t=188261

easyrider8 · **Posted:** Apr Thu 12, 2012 4:40 am

That one is different.

Dave

Flipperhome · **Posted:** Apr Thu 12, 2012 6:09 am

It's not only the same one but he got it from the same Ebay store, electronics-salon.

Dave Doughty · **Posted:** Apr Thu 12, 2012 12:46 pm

Yeah - that's the same one I bought but Dave's cost $1.00 less. I think the confusion is because my thread started out experimenting with an ancient XR2206 chip but then went OT and discussed this module which definitely seems like an improvement.

Dave

Tubenut · **Posted:** Apr Thu 12, 2012 6:34 pm

Hi Dave. I see you mention the XR2206's drift in the other thread. What kind of drift did you encounter with the LTC1799? I see their quite cheap at digikey.

Dave Doughty · **Posted:** Apr Thu 12, 2012 11:41 pm

It was more like instability due to the adjustment pots rather than drift. It was hard to set an exact frequency but I think with a fixed resistor and a lower value fine tuning pot, it would be fairly stable. When I was finally able to zero beat a broadcast station, it stayed within about 50 Hz.

Dave

Tubenut · **Posted:** Apr Fri 13, 2012 3:34 am

Ok Dave. 50Hz isn't bad... I have 5 on order from digikey. I will do a little experimenting. Thanks for the info.

Peter Bertini · **Posted:** Apr Fri 13, 2012 3:12 pm

TubeNut:

If you have a good SA, I'd be curious what the phase noise/jitter looks like in the HF region.
Circuit looks like a RC oscillator with a divider chain.

Pete

Peter Bertini · **Posted:** Apr Fri 13, 2012 4:37 pm

BTW, anyone have a link to Norm Leal's single tube "part 15" single tube AM transmitter??
I'd be willing to try one of these as a replacement for the fixed frequency crystal osc.
assembly he used in the original design.

Pete

35Z5 · **Posted:** Apr Fri 13, 2012 4:46 pm

Here ya go Pete, Norm's classic...

http://antiqueradios.com/forums/viewtopic.php?t=63310

Tom

Peter Bertini · **Posted:** Apr Fri 13, 2012 6:02 pm

Great! I will order a few of those modules today. By any chance do you have a link to to Norm's
12k5 space charge receiver project?

Pete

35Z5 · **Posted:** Apr Fri 13, 2012 8:15 pm

Here ya go Pete..

viewtopic.php?t=80109

Tubenut · **Posted:** Apr Fri 13, 2012 9:06 pm

Im purdy sure, without any filtering network on the output, the signal is probably full of harmonics. There is a divider inside too. I will fool with it when I get some time and let you guys know.

Dave Doughty · **Posted:** Apr Fri 13, 2012 10:02 pm

Tubenut wrote:

Im purdy sure, without any filtering network on the output, the signal is probably full of harmonics. There is a divider inside too.

Perhaps a low-pass filter on the grid input would be the thing to do.

I just experimented with replacing the crystal on my 5-watt LPB college transmitter. It worked well and the output was a sine wave. But it uses a 6AL11 compactron where the pentode section was the oscillator and the power pentode section has a tuned output stage.

Dave

1KHz to 33MHz Adjustable Oscillator Module Board

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