Well, I tried...I wasn't right so now I'll be left
Sorry about the bad info.
73, Larry K2LT
Gary Schafer wrote:
You can't reverse the plate leads on the modulator tubes because it uses
negative feedback from a winding on the transformer. Reversing the plate
leads puts the feed back in phase rather than out of phase. It will
oscillate!
First check to see that you have proper grid current on the 6146. Low grid
current will not allow full positive peak modulation because the tube runs
out of steam with low drive. It is much more important to have proper grid
current with AM than it is with cw. The tube has to have enough emission to
handle the peak power 4x the carrier.
Be sure the screen voltage is high enough on the 6146.
Be sure that you are not overloaded - more power than the transmitter is
rated for. If you have it loaded too heavy again the tube runs out of
emission and will not allow the modulation peaks to go high enough.
Try another 6146.
73
Gary K4FMX
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:amradio-
[EMAIL PROTECTED] On Behalf Of Jack Schmidling
Sent: Thursday, November 16, 2006 10:28 AM
To: Discussion of AM Radio in the Amateur Service
Subject: Re: [AMRadio] Ranger Modulation
Larry Taft wrote:
Try reversing the phase of the audio by swapping the output leads of the
modulation xfmr.
First I swapped the tubes to no avail. I then swapped the wires and now
have a strange buzzing that I can not locate but it shows up on the
audio with the gain at zero. Don't know if I barfed something up or not
but I vaguely remember reading somewhere that this an an indication to
reverse the leads.
Weak tube in the audio chain causing lack of gain needed for the
positive peak.
Just ordered new audio tubes.
Now I notice another discrepancy..... the manual that came with it says
to adjust the mod current to 75-90 ma. The manual that Rick sent me for
the new version which I seem to have says 55-70 and no clue why the
difference.
Which is correct and should I make an allowance for using 6L6's instead
of 1614's?
js
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