[ARC5] T-19 first run issues.

[Mike Everette]

 If you are using an MD-7 in your system, try pulling out the 12J5 tone oscillator tube and see if the hum disappears.  I had this problem before with the 1000 cycle tone leaking into the oscillator B plus.  I forget what I did to stop it, but seems like a capacitor somewhere in the MD-7 was the culprit.
73
MikeWA4DLF



    On Sunday, April 19, 2020, 02:16:56 PM EDT, J Mcvey via ARC5 <arc5 at mailman.qth.net> wrote:  
 
  Thought the A-27 was 5 ohms , but it's 12, so 2 amps is 48 watts! All good...Now al I have to do is figure out the hum situation.


    On Sunday, April 19, 2020, 1:31:59 PM EDT, J Mcvey via ARC5 <arc5 at mailman.qth.net> wrote:  
 
 Just got this ARC-5 system wired up and going. Even the rack had hacked/dry wires that needed rewiring.The T-19 was recapped, cleaned, etc.  

I have this strange problem with a hum in the carrier.  It sounds like a rig with a bad filter cap. I rechecked my wiring, etc, but everything is OK.The only other "symptom" is low output, about 2  Amps in CW mode . ( It's not the meter because I use the the same one with the SCR274 which will go 3+ amps). I'm using an A-27 dummy load

I'm thinking that it may be an alignment issue where the finals are off-resonance and drawing too much current compared to the carrier amplitude and inducing a ripple modulation? 
It's real subtle when looking at it on a scope, but obvious on a radio.
The Dynamotor is almost ripple free , putting out around 590V under load. 

Any thoughts?


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