[ARC5] T-19 first run issues.

[Mark K3MSB]

Just trying to think of some things to try......   can you series a pair of
12V car/tractor batteries for a quick test?

Mark K3MSB

On Mon, Apr 20, 2020 at 6:48 PM J Mcvey via ARC5 <arc5 at mailman.qth.net>
wrote:

> The installation is on a metal framework. The prior inhabitant, an SCR274,
> was connected to the shelf and frame better than the ARC5 is at present,
> But I make use of the ground clips on the rack. I used some clip leads to
> connect  the boxes as test to see if that helped. Unfortunately, it didn't.
> I pulled the MD7 oscillator tube as well, no joy on that either.
> The carrier hum sounds just like a 120 cycle hum from an AC supply .
> The power supply I'm using is an old industrial SMPS , so no 120 Hz from
> that!
>
> On Monday, April 20, 2020, 5:46:52 PM EDT, Michael Hanz <
> aaf-radio-1 at aafradio.org> wrote:
>
>
> Amen.  It's one of the reasons I use aluminum liberally for the support
> racks in my rig.  Reproduce the environment that they had in the aircraft,
> and you'll head off a lot of strange problems you sometimes get with
> grounding/bonding/shielding inadequacies.
>
> https://aafradio.org/flightdeck/layout.htm has some construction thoughts
> on the bottom half of the page.
>
> - Mike  KC4TOS
>
> On 4/20/2020 12:22 PM, Mark K3MSB wrote:
>
> Ground all your "boxes" together directly;  don't rely on the
> connectors.
>
> Mark K3MSB
>
> On Sun, Apr 19, 2020 at 1:26 PM 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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