NN1G trouble

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From: W. Daniel (pandora!daniel@Think.COM)
Date: Thu May 26 1994 - 07:17:41 EDT


Hi Gang,

        Here's a little update on what's been going on with the NN1G
problems I've been having. It appears that the NN1G final PA and driver is a
very unstable section. Actually, not so much the PA but the driver. Often,
when aligning the TX section, you might find your output going from 5 watts
to 12 watts even, on the watt meter. This is a sign of trouble. If you are
getting more than 3-4 watts, be suspicious. Then, turn the audio volume all
the way down and key to see if you can hear sharp clicks. If you hear a
rounded keying click, then you're probably okay. But if what you hear sounds
like a dirty contact click, or a distinct clicking, or hissing, or high
pitched whistles or oscillations, then you have instability and probably
oscillation in the driver stages. You should try this across the band as the
instability may occur only in some sections and in some cases, it may not
break into oscillation on every key, only on some random key downs. DON'T do
this with a dummy load as the dummy load usually gives no problems.
Alternatively, if you key into an open circuit and hear a loud "psssssh"
hiss instead of your sidetone, you have instability.

        When I put the signal under the scope, I saw all kinds of horrible
waveforms. So after much testing and checking, the signal is a clean sine
wave now. Even when I key into an open circuit, I still hear a clean
sidetone.

        If anyone is interested in what I did to fix it, lemme know and I'll
see if I can post my fixes/mods.

        Meanwhile, can anyone tell me where I can order some of those 10.7
MHz IF transformers used in the NN1G? I think I want to make a run of about
10 NN1G kits for my club. How much are these? Tks for any info.

72,
Daniel

-- 
+-------------+-------------------------------------+
| Daniel Wee  | daniel%pandora@csah.com             | ** Man needs more
| UUCP1.12b   | daniel.wee@f516.n600.z6.fidonet.org |  than a new start, he
| SNEWS 1.91  | csah.com!pandora!daniel             |  needs a new heart! **
+-------------+-------------------------------------+


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