On 19 Aug 2004 14:29:13 GMT, ( Doug Goncz ) wrote:

Dear Richard,

You have my thanks for your reply.

From: Richard Clark

Sounds like you need more practice soldering. All this scraping you
describe is unnecessary because you should already have bare metal.

I have 36 years of experience soldering.

Have you tried tinning Radio Shack's 274-284 connector? It acts as if it's made
of stainless steel. Maybe a chisel tip would work better.

Why would Radio Shack spend more for stainless steel? Who in their
right mind would produce it? I have never had any problems with the
cheapest of materials to wet with solder. You are having some other
difficulty and it may be this wire you are trying to use (ever try
soldering old telephone wire?). Does it wet easily?

I think there's a reflection at the jack, forming a resonant tank. The
frequency depends on the cable length. A little less than 20 feet.

20 feet is not resonant (first resonance that is) at any particular
commercial frequency.

it is your attempts
to connect the twin lead to it (if that is what you mean by twinax).

I had used twinlead. I went to twinxial cable, two 20 gage conductors with
polyethylene around them, in a polyethylene carrier, with a foil shield and
what must be close to 100% overbraid. It is Coleman Cable 99301 20 gage 100 ohm
twinaxial type CL2.

You need to go to radio shack and buy a TV-Coax BalUn.

No, this is a stereo phone plug with balanced signal on tip and ring. I have
added ground on the barrel.

Sleeve.

The original antenna is a 22 gage dipole insulated
with polyethylene, not PVC.

Immaterial really.

Each leg is 30 inches long. The pair to the plug
is 39 1/2 inches long.

Still rather immaterial. There are optimal lengths, but trivial for
receivers.

We're on the third floor. I note that if the antenna is allowed to tilt, the
signal fades.

Indicative of multipath rather than actually pointing at the
transmitter. Your antenna is looking into a soup of direct
transmission waves, and reflections, re-reflections and so on.

Alternatively, you don't have enough signal, and all the tilting,
wiring, jacking, and soldering in the world is not going to make up
for it. Add about 10dB of amplification at the antenna.

I have replaced the cigarette pack spacer by a foam block. It's
level now. The boom surface is three inches from the ceiling. Should it be
farther from the ceiling?

There is nothing good about its close proximity. However, it may be
benign. You should not be as close as the length of any antenna
element from other conductors (you don't know what is in the ceiling
for the thirty odd inches proximity).

I just filed up a chisel tip.

That is poor practice. You are already melting the connector's
plastic. Solder should flow within seconds at these small dimensions
for even a 30W iron with a pencil tip.

This morning I lengthened the lead from the antenna to the twinax by stripping
more shield, foil, and filler. Now it works very badly. No stereo reception of
WHFS. Extending the sheild with foil helped. The legs are 18 inches long.

Like I said, this is all futile reminiscent of tin foil rabbit ears
aligned with the rising moon and setting Venus. Your signal is
marginal and suffering from multipath to boot.

What I need is:

How long should the legs be at the antenna end?

Length is not an issue, separation is. Even here it is of no
particular concern. The enforcement of that is dictated by the
mechanical connections at the antenna and the taper to the usual,
conventional twin line has been commonplace for 60 years.

How long should the filler alone be?

How long should the section with foil over filler be? (Should this foil be
tapered?)

How long should the braid be?

These are unconventional and cannot be said to be aiding you whatever
optimal values may be offered.

How long should the rest of cable, in its natural condition be?

The only criteria is that it should not be so long as to attenuate the
signal through loss. Conventional installations for years went tens
of feet to a hundred feet - depending upon signal strength. You don't
have signal strength.

What's a good way to terminate the twinaxial cable to the phone plug?

I seriously doubt you have a female stereo connector to plug into -
this too is unconventional. If you do, the sleeve connection was
never used in the original configuration (the original antenna only
had two leads to begin with by your description).

Twinax (Triax) is not conventional and you give every appearance of
either shorting out the antenna, and only picking up opportunistic
signal strength; or you have a floating shield that is picking up
opportunistic signal strengths and coupling it randomly into the
receive signal from the antenna. Either way, there is something
definitely fishy about the arrangement. If you want to persist with
using twinax, connect the two shields together at both ends (and at
the phono end, going to the ring, and the center conductor to the
tip), and do not make any sleeve connection at the radio.

Now what, I wonder?

Buy an amplifier.

73's
Richard Clark, KB7QHC