When adding a PL-259 connector to a radio that doesn't have one (a radio
that is set up for longwire only), is it OK to just wire it straight in, or
is it best to add some sort of impedance-matching circuit? Obviously the
long-wire connector is going to be high-impedance, while the coax coming in
will be 50ohm.

I often see radios that someone has added the connector. I'd like to add
one to an old DX-150A, just for convenience since my longwire comes into the
house via coax. A already use a MLB between the longwire outside and the
coax; the antenna works great on radios with a 50ohm input.

Any advice? Thanks.

Jeff

Unrevealed Source wrote:
I often see radios that someone has added the connector. I'd like to add
one to an old DX-150A, just for convenience since my longwire comes into the
house via coax. A already use a MLB between the longwire outside and the
coax; the antenna works great on radios with a 50ohm input.

Any advice? Thanks.

Ferrite is cheap. Why not put a 3:1 (turns) balun inside the
radio between the SO-239 connector and the original antenna
terminal.

(another) Jeff


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under the Internal Security Act of 1950.

"Jeffrey D Angus" wrote in message
...


Unrevealed Source wrote:
I often see radios that someone has added the connector. I'd like to add
one to an old DX-150A, just for convenience since my longwire comes into
the house via coax. A already use a MLB between the longwire outside and
the coax; the antenna works great on radios with a 50ohm input.

Any advice? Thanks.

Ferrite is cheap. Why not put a 3:1 (turns) balun inside the
radio between the SO-239 connector and the original antenna
terminal.

(another) Jeff



There's no guarantee that the radio has a defined input impedance to begin
with!
You could try a balun to see what improvement it makes on various stations,
but with a random length wire the antenna impedance is going to be all over
the place. If you're really worried about matching, use an antenna tuner. It
probably isn't going to make that much difference.

Pete

Uncle Peter wrote:
"Jeffrey D Angus" wrote in message
...

Unrevealed Source wrote:
I often see radios that someone has added the connector. I'd like to add
one to an old DX-150A, just for convenience since my longwire comes into
the house via coax. A already use a MLB between the longwire outside and
the coax; the antenna works great on radios with a 50ohm input.

Any advice? Thanks.
Ferrite is cheap. Why not put a 3:1 (turns) balun inside the
radio between the SO-239 connector and the original antenna
terminal.

(another) Jeff



There's no guarantee that the radio has a defined input impedance to begin
with!
You could try a balun to see what improvement it makes on various stations,
but with a random length wire the antenna impedance is going to be all over
the place. If you're really worried about matching, use an antenna tuner. It
probably isn't going to make that much difference.

Pete


I would add a small series capacitor (maybe 0.01 uF), not for impedance
matching but for safety in case a high-voltage fault develops inside the
radio. As Pete says, the input impedance over a 3:1 bandwidth will be
all over the map. You might match it over a 10% bandwidth. But 3:1? No way.

Bill Jeffrey

"Unrevealed Source" wrote in message
...
When adding a PL-259 connector to a radio that doesn't have one (a radio
that is set up for longwire only), is it OK to just wire it straight in,
or
is it best to add some sort of impedance-matching circuit? Obviously the
long-wire connector is going to be high-impedance, while the coax coming
in
will be 50ohm.

I often see radios that someone has added the connector. I'd like to add
one to an old DX-150A, just for convenience since my longwire comes into
the
house via coax. A already use a MLB between the longwire outside and the
coax; the antenna works great on radios with a 50ohm input.




For receiving, it won't be too critical...
but I assume you mean to add an so-239

"philo" wrote in message
news

"Unrevealed Source" wrote in message
...
When adding a PL-259 connector to a radio that doesn't have one (a radio
that is set up for longwire only), is it OK to just wire it straight in,
or
is it best to add some sort of impedance-matching circuit? Obviously
the
long-wire connector is going to be high-impedance, while the coax coming
in
will be 50ohm.

I often see radios that someone has added the connector. I'd like to add
one to an old DX-150A, just for convenience since my longwire comes into
the
house via coax. A already use a MLB between the longwire outside and the
coax; the antenna works great on radios with a 50ohm input.




For receiving, it won't be too critical...
but I assume you mean to add an so-239

I agree. But, if you run coax outside to the longwire,
a Balun at the feedpoint will mitigate the problem.
Someone did a nice webpage on a system like that,
and it also lessens the pickup of interference generated
by household electrical items.

Pete

Unrevealed Source wrote:
When adding a PL-259 connector to a radio that doesn't have one (a radio
that is set up for longwire only), is it OK to just wire it straight in, or
is it best to add some sort of impedance-matching circuit? Obviously the
long-wire connector is going to be high-impedance, while the coax coming in
will be 50ohm.

I often see radios that someone has added the connector. I'd like to add
one to an old DX-150A, just for convenience since my longwire comes into the
house via coax. A already use a MLB between the longwire outside and the
coax; the antenna works great on radios with a 50ohm input.

Any advice? Thanks.

Jeff

The following free advice is worth every penny... :-)

When you say you want to put a connector on the radio, do you mean the
male (PL-259) or the female (SO-239)?

Don't worry about matching the impedance. It is relatively non-critical
for short wave listening. However, you may want to devote a little
attention and thought to some kind of lightning protection.

Finally, if you mean an SO-239 to be mounted on the radio, I vote "no",
only because IMHO, it buggers up the radio and reduces what ever resale
value it may have; however, this is just my personal pet peeve.

Yes, as someone else pointed out, I meant SO-239 (the female end). I'm not
worried much about resale; it's just an old DX-150A to play with and I've
already repainted the case.

"Carter-k8vt" wrote in message
...
Unrevealed Source wrote:
When adding a PL-259 connector to a radio that doesn't have one (a radio
that is set up for longwire only), is it OK to just wire it straight in,
or is it best to add some sort of impedance-matching circuit? Obviously
the long-wire connector is going to be high-impedance, while the coax
coming in will be 50ohm.

I often see radios that someone has added the connector. I'd like to add
one to an old DX-150A, just for convenience since my longwire comes into
the house via coax. A already use a MLB between the longwire outside and
the coax; the antenna works great on radios with a 50ohm input.

Any advice? Thanks.

Jeff

The following free advice is worth every penny... :-)

When you say you want to put a connector on the radio, do you mean the
male (PL-259) or the female (SO-239)?

Don't worry about matching the impedance. It is relatively non-critical
for short wave listening. However, you may want to devote a little
attention and thought to some kind of lightning protection.

Finally, if you mean an SO-239 to be mounted on the radio, I vote "no",
only because IMHO, it buggers up the radio and reduces what ever resale
value it may have; however, this is just my personal pet peeve.

Bill Jeffrey wrote:

I would add a small series capacitor (maybe 0.01 uF), not for impedance
matching but for safety in case a high-voltage fault develops inside the
radio.

Well, as this is a solid-state radio, I don't know if a "high-voltage
fault" would be a big issue or not... ;-)

Carter-k8vt wrote:

Don't worry about matching the impedance. It is relatively non-critical
for short wave listening. However, you may want to devote a little
attention and thought to some kind of lightning protection.

Well, that depends. IF you attach a long wire antenna to a 50 ohm
coax cable, then the coax cable to an input on the radio whose impedance
is changing, that coax cable becomes part of the antenna system and ceases
to be a transmission line.

In the case of a long-wire antenna, the result is minimal. Maybe it
changes the antenna pattern in a minor way, but you won't notice any
real difference.

BUT, now take a highly directional antenna which you are swinging around
to avoid a noise source.... run that into the 50 ohm cable and into the
high-Z receiver, and now the signal pickup on the transmission line will
become a problem.

Finally, if you mean an SO-239 to be mounted on the radio, I vote "no",
only because IMHO, it buggers up the radio and reduces what ever resale
value it may have; however, this is just my personal pet peeve.

And there is no reason not to just make a PL-239-to-pigtails cable, if
you're plugging the receiver into a distribution box or T/R relay that
has SO-239s on it.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."