The variable capacitors are little polyvaricons. I got these cute little dials for them, but still need to find some screws to hold them in.
I threw some wire out the door and was able to hear some stations! The thrill of hearing anything on a radio you built yourself is *awesome*.
Unfortunately, it is quickly replaced by the annoyance that it isn't doing *quite* what you want. For one, it isn't quite on the frequency I want. I made a rookie mistake and mounted the variable capacitors on veroboard (it was late and I was excited to be close to done...), which seems to have added a bit of capacitance. I also found I had a wrong cap in somewhere. So, I haven't quite got it to the 7-7.125 MHz range I was going for.
Also, it is *really* hard to tune. I think a third padded down cap would help a lot, but getting it right on a station took a lot of practice. Even as I got the hang of it, it was kind of harsh to listen to, and the whining as you got close to a station got old quick.
All in all, I'm counting this as a huge success. But I don't think I'm going to keep it as is for long. I got an AD9850 off of Ebay the other day that I think I'm going to try in place of the tuned circuit here. Partially because I want to play around with the DDS, partially because the little variable caps here are fiddly.
This is my first Manhattan-style build, and I looked at a *lot* of examples before starting. I need to give huge props to KK6GXG - his build was a huge inspiration.
Unfortunately, it is quickly replaced by the annoyance that it isn't doing *quite* what you want. For one, it isn't quite on the frequency I want. I made a rookie mistake and mounted the variable capacitors on veroboard (it was late and I was excited to be close to done...), which seems to have added a bit of capacitance. I also found I had a wrong cap in somewhere. So, I haven't quite got it to the 7-7.125 MHz range I was going for.
Also, it is *really* hard to tune. I think a third padded down cap would help a lot, but getting it right on a station took a lot of practice. Even as I got the hang of it, it was kind of harsh to listen to, and the whining as you got close to a station got old quick.
All in all, I'm counting this as a huge success. But I don't think I'm going to keep it as is for long. I got an AD9850 off of Ebay the other day that I think I'm going to try in place of the tuned circuit here. Partially because I want to play around with the DDS, partially because the little variable caps here are fiddly.
This is my first Manhattan-style build, and I looked at a *lot* of examples before starting. I need to give huge props to KK6GXG - his build was a huge inspiration.
Greetings Ben,
ReplyDeleteThank you for the kind words. I am very pleased that my post was helpful to your build of this DC receiver. One of the greatest joys in amateure radio for me is knowing that I contributed in some way to someone else's project success.
Keep making solder smoke!
73,
~Jon KK6GXG
It really did. This was first time using Manhattan/MePads/etc, and I spent ages trying to get my head around how to lay out things. The close-up pictures you had of the way you did your ICs was what finally got my head in the right space.
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