103. AM FM Final Alignments

[@harveyellis6758]

Great to see you doing videos again! They are well presented and very educational.

[@TheOffsetVolt]

Thank you. Took me a long while to get back and am trying to get the swing of things again. Thanks for watching.

[@aerofart]

SO glad you’re back, Offset! I enjoy your videos very very much!

[@TheOffsetVolt]

I am glad to hear you like the videos. Hope to keep making more and better for some time.

[@davidmackay1198]

Good to see you back, thought covid might have got you!

[@TheOffsetVolt]

Not Covid, although it did leave me with, of all things, a knuckle pad. Strange damn disease. Hence, the bandage. Thanks for sticking around all this time.

[@WECB640]

Many of these kits came with a LM386 that was not genuine but a cheap copy that did not perform well. If you have a carrier or birdies on AM, this is the culprit. The chip goes into RF oscillation easily. It's like trying to tune/align a regenerative receiver. You can tune for max output on the IF when in AM mode, but I would not peak the FM IF this way as it is far too narrow and will cut the sidebands. Instead, inject 10.7MHz but have it sweep about 10KHz either side of carrier as you observe the RF output on a tracking generator. You want max gain BUT with wide flat bandwidth. This is important to reduce distortion on FM. Good luck.

[@TheOffsetVolt]

You are absolutely right. Some of the transformers are "marginal" at best. I ended up using a genuine 386.

[@aerofart]

That’s good to know. It’s unfortunate that a company like Elenco that rolls around in piles of cash can’t be bothered to spend a few extra cents to provide their customers with decent parts and a proper experience that they’ve taken us most of the way through. The kit is really decent, they should go that extra bit to make it excellent. I hope I can remember where to find your comment when I get to the FM sections of the build. I’m sure it will come in handy. Thanks.

[@vincei4252]

Yes, it has been a long time. Good to see you're healthy and doing well. My radio is also frozen in time waiting for the continuation of this series.

[@TheOffsetVolt]

Thanks for the welcome. Hope that radio is working soon.

[@stargazer30721]

Glad you're back! Love your videos! I'm having difficulty seeing the 1kHz waveform on my oscope while tweaking the IF transformers. I'm a total newbie with a scope. What are the setup parameters on your oscope? I learning just as much about function generators, VOMs and oscolpes as anything else here. Any advice is appreciated :-)

[@wsscott72]

I've built this kit and have been working on the tuning procedure. I can get AM and FM stations pretty good. The AM stations line up with the Dial. But the FM stations are way off from the dial. For example, if I turn the Dial to get station 91.1, it shows as being around 104 on the DIAL! Basically on the FM stations, the low stations appear in the higher numbers on the dial, and the higher numbers appear in the Lower numbers on the dial. What's going on, and how do I fix it? Thanks.

[@gregoryharding419]

I'm building the radio, all seems to be going well. However, I am having trouble measuring gain and bandwidth. I am using a Siglent SDG1025 function generator and a Rigol DS1054 scope. Both seem unable to produce waveforms accurately below 100mV. Any suggestions?

[@davidluther3955]

I JUST WONDERED WHAT CITY AND STATE YOUR VIDEOS ARE COMING FROM? I AM FROM ALBUQIERQUE NEW MEXICO.