Ground loops with Lectrosonics T1

Peter,

Appreciate your comments.  At present I have sent the T1 back to Lectrosonics
just to double check the unit.  Apparently there is a posibility that some or
all of this could be cause by a bad DC to DC converter.  Ultimately however, I
think I am going to have to transformer isolate the unit as you did.   Because
I often have to use an "over the shoulder" mixer I will probably look for a
lighter weight solution such as a transformer built in to the XLR connector.

Thanks for your help,
Tom

Tom,

Why don't you also consider using the T2 transmitter for your over the
shoulder work. The T2 looks just like a Lectrosonics frequency agile belt
pack upright antenna transmitter and is just as easy to use. It also take an
internal 9volt battery so you won't have any over the shoulder powering
issues to deal with. You could also use both transmitters together on
separate frequencies when on your cart for two different feeds because the
receivers are capable of receiving multiple channels (one for the director's
feed, the other for your sound assistant or boom operator.) I also feel the
250mw output of the T1 is a bit too much rf to have floating around so close
to your radio mic receivers when over the shoulder. The T1's 100mw is more
than ample for most applications. In fact I used a T1 on the bridge  of a
Trident Nuclear Submarine that was at dock. The client (couldn't squeeze
them in) was able to hear perfectly from dockside. If they will penetrate
the most awesome weapon known to mankind.... they should do just fine for
you!

Charles Tomaras
toma @tomaras.com
Seattle, WA    USA

Tom,

I ended up using a whirwind line balancer/splitter to help solve this problem
with my T1. The whirlwind box transformer isolates & splits a line level signal
& will balance an unbalanced line level source. It has a 1/4" unbalanced input,
 XLR F balanced input & 2 XLR M outputs, each with switchable ground lift
switches. One XLR output is switchable between isolated & direct output, the
second is always isolated. The box requires no power.
It REDUCED my oscillation considerably, but I Haven't had time to troubleshoot
& eliminate it completely.
BTW, this box is also handy for an extra feed for the EPK crew.

Hope this helps,
Regards,
Peter

Call Lectrosonics at 1-800-821-1121 and they will help you trouble shoot
your problem. I have the T-2 transmitter and haven't had any problems of
that sort, but it is a different animal than the T-1.

Charles Tomaras
toma @tomaras.com
Seattle, WA    USA