To 160 or Not To 160, that is the question..

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To 160 or Not To 160, that is the question..

Postby N3LRX » Tue Feb 20, 2007 11:23 am

Just wondering..

If I decide to build a 75m only rig I would simply omit L1, RY1, RY2, C10, and C15.

Would any changes have to be made to L2 and the rest of the RF chain? I wouldn't think so, since the band switching only adds or shorts a coil, and adds or removes capacitance. But just thought I'd ask.

I'm thinking of possibly building separate RF Decks for each band and using a common modulator.
73 DE Randy N3LRX
You can't spell HAM without AM!
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Postby KD3CN » Tue Feb 20, 2007 12:51 pm

Hi Randy,
Well, there's advantages and disadvantages either way (seperate decks or one 2-bander), and they're fairly obvious.

I'll just say this about that. This past weekend I finally had all the bugs out of my new rig, which is the current 2-band deck design. Except for the rf deck testing done at Hosstraders last fall, all testing on the completed rig had been done on 75m. When it came time to test 160m, I threw the bandswitch and VFO, going from 3885 to 1885(with a bit of trepidation, I'll admit!). It came up looking just as good on 160 as 75, and I didn't even have to touch the tuning cap. A little more load capacitance and she was singing on 160! :D

To each his own, but I'm glad I went two-band, mainly because I wanted to get on the air on both bands as quickly as possible. For my next one I'm actually thinking seperate decks... :wink:

What the heck, if you've already made both coils and bought the relays, why not two-band it? Even if you do build another 160m deck, you'll have a backup on that band!

73, Karl
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Postby N3LRX » Tue Feb 20, 2007 1:12 pm

I just wonder if it's worth it tho.. I've been listening around on 160m lately and I really don't think I'm going to be able to really use it. There's just too much noise.. Dunno where it's coming from but the noise level just about wipes out the band.

If I can't hear, doesn't do me any good to talk.. :) I may yet change my mind. The interference may be season related. Allot of people around here have Oil Burners so it could be interference from the ignition on them. We'll see how the weather is and if it warms up long enough for me to get a good idea if that's the problem or not. Hopefully I won't have to wait till summer to get a rig working!

It could also be the railroad tracks as well which are a stones throw away. I don't know what frequency their signaling equipment works on. It may be close enough to raise the noise floor on 160.
73 DE Randy N3LRX
You can't spell HAM without AM!
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Postby KD3CN » Tue Feb 20, 2007 6:40 pm

Ok Randy,

Well, I don't have a lot experience on 160m, after all, I only just finished the rig! But the antenna I put up is very marginal, and typically I hear nothing but a lot of LOUD noise when I check the band, even at night... Accept when I don't!!! Sometimes there are very strong, typically local am signals. It would be easy to give up on the band, especially when using a marginal antenna like mine. But there have been plenty of times when 75 was trashed and I heard beautiful signals when checking 160m! I guess you may well have a lot of local noise ruining your fun, but don't give up on this great band too quickly!

As for leaving 160 out of the rf deck, I don't see why you couldn't just omit the relays, coil and 160m shunt caps. I used 3 470pf ATC shunt caps per module on 75m, and an additional 1000pf doorknob switched in for 160m. Per Steve's recommendation, I used a lower amount of capacitance than what's shown on the schematic when using the ATC caps.

73, Karl
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