[R-390] R-390 alignment questions

[Veenstra, Lester]

Of course doing the balance nul adjustment assumes you are goung to feed
your rhombics with long runns of latter line in a noisy environment HI
Les K1YCM/3 (xCTM1)

-----Original Message-----
From: r-390-bounces at mailman.qth.net
[mailto:r-390-bounces at mailman.qth.net] On Behalf Of John KA1XC
Sent: Tuesday, October 12, 2004 10:41 PM
To: R-390 reflector
Subject: Re: [R-390] R-390 alignment questions


> I thought I would go back and input a signal on the balanced input 
> through two 68 ohm resistors and set the balance trimmer for each band

> only to
find
> the radio pretty much deaf.

Cecil,
for doing the balance adjustment that's perfectly normal. I've found
that to get a hearable signal for nulling I need to set the generator
output several orders of magnitude greater. (Think about it, if the
input balance was perfect you'd never hear ANY common mode signal).

RF alignment is best done using the low-z balanced input with one side
grounded (thus making it unbalanced) and connected directly to the
signal generator output. Connecting a 50 ohm sig gen output to the hi-z
unbalanced input will work of course but you're *really* loading down
the front end tuned circuit and probably getting a much broader peak
during its alignment.

John



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