Interesting. I'll bet that no two TR7s will behave exactly the same in
this respect since there are several adjustments involved, and they've
probably all been adjusted differently after all these years. I haven't
seen that fuzzy signal problem, but as I said I have my output cranked
back a ways.
73, Floyd
On 3/3/2014 9:57 PM, Jim Shorney wrote:
Thanks for the comments, Floyd. I have noted with my TR-7 that if I get into
ALC on CW the sidetone starts to sound "rough" and a scope on the carrier shows
what looks like some AM "fuzz" starting to show up on the signal. I was never
sure if this was a problem or not as the owner's manual does state that
advancing the carrier control past the point where the light comes on "may
result in undesirable keying characteristics". I've seen a couple of other
TR-7s do something similar. I may look into it at some point, but as long as I
stay below ALC illumination everything looks fine. Using even a little ALC to
"level" the carrier on transmit doesn't sound like a good idea anyay.
73
-Jim
NU0C
On Mon, 03 Mar 2014 16:11:24 -0500, Floyd Sense wrote:
In the "Tweak my peak" thread, NU0C said this:
/On CW, definitely operate below the ALC level. The quality of the transmit
signal starts to degrade when you go into ALC.//
/
I decided to take a look at that today, using my Orion II and NaP3 panadapter
to examine the TR7 output spectrum as the ALC was varied. My TR7 is setup to
put out 100W at the point on the carrier level control just before where the
the LED comes on (on 20M). The TR7 was operated into a dummy load and the
Orion had no antenna connected and 18 dB of attenuation dialed in so the TR7
signal didn't overdrive the panadapter range.
I watched the panadapter display as I rotated the carrier level control from
that point to full clockwise. The ALC LED came on at about the 1 o'clock
position. The power maxed out at 115 watts. I saw no change in the spurs I
saw at all over that range. The strongest spurs were 60 dB down from the
carrier.
So, it appears, at least on my TR7, that there is no degradation in the CW
signal (looking 40 KHz in each direction from the carrier) that is related to
ALC action. Maybe if my TR7 were adjusted for maximum output, other factors
might cause increased distortion that would appear to be related to the ALC
level (but might not be).
I checked again on 10M CW (where my max output is set to 80W) and found the
same thing to be true (but spurs were 67 dB down).
73, Floyd - K8AC
--
“There’s something out of place – let’s go and poke it with a stick.” – The Doctor,
"Amy’s Choice"
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