[Collins] 51J4 and AC Power gremlin questions (long post)-
Clarification
Chris Kepus
ckepus at comcast.net
Sun Nov 6 03:28:32 EST 2005
Hi Mac,
Thanks for the comeback. Just a clarification for you and maybe others.
The 51J4 and 75S3 are completely isolated from the AC wiring. They are not
part of the AC wiring gremlin. They are deriving power from an isolation
transformer plus a variac to keep the AC volts in the 115 V range. The AC
power problem was not caused by the receivers. I did post a couple of
questions about the 51J-4 filter insertion loss and maybe I should have kept
them separate from the AC power problem and questions.
As far as the GFCI is concerned, I removed it from the circuit and bypassed
it to eliminate it as a potential cause of the AC problem.
73 and Tnx,
Chris
W7JPG
-----Original Message-----
From: Mac McCullough [mailto:w5mc at austin.rr.com]
Sent: Saturday, November 05, 2005 11:35 PM
To: Collins at Mailman.Qth.Net
Cc: Chris Kepus
Subject: Re: [Collins] 51J4 and AC Power gremlin questions (long post)
this is you AC line filter caps, leaking or bad, as well you dont say if
your receiver is a 2 wire cord or a three wire cord set .. im guessing a 2
wire cord set .. and the mere possibility of switching the plug from one
side to the other will place the HOT wire from the receiver cord into the
neutral side of the GFCI receptacle .. and this might not be the exact
answer but it will be damn close ... I personally would never have
installed a GFCI into this system, if any set I was or did use I would
first convert it to a full 3 wire cord system, and never look back at not
using a gfci.. but that if your using a 2 wire supply cord, then it's very
possible to get one side pushed in correct polarity wise, and another one
reversed thus you can end up between the various sets in the right sequence
seeing 120vac just by example touching one set and another, both at the same
time .. GFCI's dont have a place in my shack... the RFI emanating from a
Amplifier or les than pure xmitter stray as it might be will trip a GFCI ...
but you have to do what you feel works best for you and then live with the
experience of it .. the 51j stuff has a bathtub cap or some have a disk cap
right onto the power input line, if these start to leak, the gfci will see
this and do what it does best .. and what it was designed to do when it see
stray voltages .. good luck mac/mc w5mc
Located 46 miles due North of the Alamo, and 121 miles due South of the
Western White House. see my website at www.collinsandharrisradios.com
----- Original Message -----
From: "Chris Kepus" <ckepus at comcast.net>
To: <collins at mailman.qth.net>
Sent: Sunday, November 06, 2005 1:16 AM
Subject: [Collins] 51J4 and AC Power gremlin questions (long post)
>
>
> Friday evening I finally hooked up and started using my 75S3 and 51J4.
> Sadly, the beginning of my fun was interrupted by a very strange and
> bewildering power problem that I am submitting to the group in the hopes
> that someone has "been there" or "done that". My shack wiring is two
> years
> new, wired and inspected to code. The power source for the circuit in
> question is a 120V 20 Amp breaker followed by a 20 amp GFCI. The GFCI
> output feeds 7 duplex receptacles in the shack. The circuit has been in
> use
> over the past two years and has worked FB.
>
> Friday evening this circuit was feeding my Collins receiver "power supply"
> (a variac controlled isolation transformer) which in turn was providing
> power (and "power on" switching) for my 75S3 and 51J4. All was well. It
> was the first time in several years that the 51J4 was fired up. It worked
> great. I did notice, however, that the 3 kc filter on the 51J noticeably
> reduced the signal strength compared to the 6 kc filter (even more than
> the
> 1 kc filter). I also noticed that if I switched in the crystal filter to
> position 1, the signal strength increased on all the mechanical filter
> positions. Hmmmmmm. Why is that? I know filters have insertion losses
> but
> I didn't think there was that much difference between the 3 kc and 6kc
> filters. Is this normal? Why did switching in the crystal filter make
> such
> a positive difference?
>
> Saturday evening, I went back into the shack to resume my play with the
> receivers. I turned on the "power supply" but the pilot light didn't come
> on and the receivers didn't light up. Scratching my head, I checked the
> power plug. It was solidly in the receptacle. I tested the GFCI and
> cycled
> it. It was OK. I checked the 20 Amp breaker. It was "ON" (normal) but I
> cycled it anyway. But the outlet my "power supply" was using was still
> dead. I checked for power on the circuit by plugging a lamp (with a known
> good bulb) into each of the other 6 receptacles with the same result as
> with
> the receivers. No power/no light.
>
> I unplugged everything that was on this circuit and then performed two
> tests
> on all the receptacles. For the first test, I used a plug-in circuit
> tester
> that tells you with a three light combination if you have wired the
> receptacle correctly or if you have a problem. All the receptacles tested
> AOK. More head scratching. What the heck is going on? For the second
> test, I took my multimeter, checked all the receptacles and found 120V at
> each receptacle. I felt better. Where there's power, there's light! I
> plugged in the lamp and switched it on. The light did not come on.
>
> Now I am into very serious head scratching. What the H--- is going on?
> Determined to figure out what was going on, I moved to a set of side by
> side
> duplex receptacles for yet another test. I plugged in the circuit tester,
> plugged in the lamp (turned off) and connected my multimeter to the third
> outlet. With the breaker "ON" and the lamp switched off, the circuit
> tester
> showed AOK (wired correctly) and the multimeter showed 120 V.
>
> I then switched the lamp on. Rats! No light...again. But the circuit
> tester light pattern changed from AOK to a pattern that indicated the "Hot
> and Ground wires are reversed", and the multimeter reading was now "zero
> Volts"! What???!!! When I switch the light off, the circuit tester
> pattern
> changed back to AOK and the multimeter showed 120V. !! In the meantime,
> the
> breaker did not trip. I did bypass the GFCI but that had no effect.
>
> So in summary, when there is nothing plugged into this circuit, both the
> circuit tester and the multimeter results on each of the receptacles are
> positive.
>
> The instant a load is connected (plugged in, turned on) the circuit tester
> indicates the "Hot and Ground wires are reversed", and the multimeter
> reading shows "zero Volts"! This result is the same regardless of the
> receptacle being used.
>
> So gents, does anyone have an idea about what is going on with either the
> 51J4 or with my wiring gremlin?
>
> Please excuse the long post,
> 73,
> Chris
> W7JPG
>
> ______________________________________________________________
> Collins mailing list
> Home: http://mailman.qth.net/mailman/listinfo/collins
> Help: http://mailman.qth.net/mmfaq.html
> Post: mailto:Collins at mailman.qth.net
>
>
More information about the Collins
mailing list