[Drakelist] T4XB RF Into Modulator

[Richard Knoppow]

    In the levels data sheet you sent me some time ago it 
states that the LO level at the wiper of the carrier null 
pot should be about 4.2 V P-P. Please confirm this is the 
right level. On my pet problem the level is a bit under a 
volt P-P. This is on either side of the coupling cap or with 
the cap lifted off the pot. I tried a different tube, made 
no difference. If this level is really so much lower than it 
should be it could explain a lot of things including what I 
had thought was low gain in the mic amp.
    BTW I changed a couple of the coupling caps in the 
audio circuit. No differnce. One probably needed to be 
changed any way because the case was coming off.
    I assembled the circuit board for the Heathkit Shop 
AC-4 mod but have not yet installed it. Assembly is a 
breeze. I found the ripple on the HV supply under load was 
very high. Can't remember what I got but perhaps 60 or 70 V 
P-P saw-tooth, definitely bad caps although the DC level 
stays fairly high.
    A combination of a bad PS and low RF levels would well 
explain the output level being somewhat down.

--
Richard Knoppow
Los Angeles
WB6KBL
dickb...@ix.netcom.com 


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