Re: [IRCA] coax update

["Chuck Hutton" <charlesh3@xxxxxxx>]

Patrick:

I hope you'll repeat the test with a transformer designed for MW use. TV
splitters are rarely good for frequencies as low as the broadcast band. To
cover .5 MHZ to over 500 MHZ in one design is tough.

I'd assume your TV transformer is a 75 to 300 Ohm transformer, so it's not
the impedance you need either.

I've had no luck trying to find small, sealed metal boxes at Home Depot and
have just bought them from eBay.


Chuck

-----Original Message-----
From: irca-bounces@xxxxxxxxxxxxxxxx [mailto:irca-bounces@xxxxxxxxxxxxxxxx]
On Behalf Of Patrick Martin
Sent: Sunday, August 19, 2007 7:02 PM
To: irca@xxxxxxxxxxxxxxxx; am@xxxxxxxxxxx
Subject: [IRCA] coax update

I found an old Sony TV matching transformer in a metal box. I pryed off
the back and removed the coil, leaving the coax fitting. I drilled two
holes and added two banana jax, and then installed the transformer,
closed it up, replaced the banana plugs with a regular fitting on the
coax outside, and then put a terminator on the end and then checked for
leakage before I attached the transformer. Well, quite an improvement to
say the least. Not perfect, but better.
On CBU-690 I found a weak signal, not audible, but a few stronger
Portland & Seattle stations were S2-S4. I found the three locals at S9.
The higher the frequency the stronger the signals. KAST-1370 was
stronger than KSWB-840.
I then removed the termination and added the matching transformer and
checked across the dial. I did find signals 90 degrees off from the
beverage in many cases to be weaker. KAST-1370-Astoria to the North was
S9+32 instead of S9+38. 1300 KKOL Seattle had more QRM from KACI The
Dalles OR. So it made a difference. No doubt about it. It will be
interesting to connect Quad RG6 and see what happens. But the matching
transformer in a metal box did improve the directivity of the beverage. 
   I stopped by Radio Shack and they did not have any small metal boxes.
The only small one they had was plastic with a metal bottom. I will have
to check around and see if Home Depot has any the next time I am in
Portland. I would like to replace all of the other three matching
transformer boxes.
   Thanks everyone for the great advice. Much appreciated.
   Oh by the way, attaching the clip from the ground rod to the coax
shield now make practically no difference. Installing the matching
transformer in the metal box seemed to have corrected that.

73,

Patrick

Patrick Martin
KAVT Reception Manager

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