Antenna impendace matching for old tube receivers
 

Hello,
I've purchased an 1962 tube HF receiver. Well the problem is I don't know
exact antenna input impendence value of it. I use simple 40m. dipole on a
regular TV cable of 75 ohm. I would like to do some experiments with random
wire, and 50 Ohm coax or 300 Ohm ladder line for dipole. Is there any
circuit that can help me to mach the impendence?

Thx,
Edgar
73!

On Mon, 24 Nov 2003 22:32:08 +0200, "Edgar" wrote:

Hello,
I've purchased an 1962 tube HF receiver. Well the problem is I don't know
exact antenna input impendence value of it. I use simple 40m. dipole on a
regular TV cable of 75 ohm. I would like to do some experiments with random
wire, and 50 Ohm coax or 300 Ohm ladder line for dipole. Is there any
circuit that can help me to mach the impendence?

Thx,
Edgar
73!


Hi Edgar,

How many tubes does it have?

73's
Richard Clark, KB7QHC

receiver input impedance is usually not too important... but proper matching
can increase the signal getting to the receiver and give better sensitivity.
use the same type of matching network as for a transmit antenna, though
smaller components are permissable of course. adjust for max receive signal
unless you have proper test equipment to measure input impedance. some old
radios included a simple peaking control that did some input matching, check
the schematic for anything adjustable before the first rx rf amp tube.

"Edgar" wrote in message
...
Hello,
I've purchased an 1962 tube HF receiver. Well the problem is I don't know
exact antenna input impendence value of it. I use simple 40m. dipole on a
regular TV cable of 75 ohm. I would like to do some experiments with
random
wire, and 50 Ohm coax or 300 Ohm ladder line for dipole. Is there any
circuit that can help me to mach the impendence?

Thx,
Edgar
73!

On Mon, 24 Nov 2003 22:32:08 +0200, "Edgar" wrote:

Hello,
I've purchased an 1962 tube HF receiver. Well the problem is I don't know
exact antenna input impendence value of it. I use simple 40m. dipole on a
regular TV cable of 75 ohm. I would like to do some experiments with random
wire, and 50 Ohm coax or 300 Ohm ladder line for dipole. Is there any
circuit that can help me to mach the impendence?

Thx,
Edgar
73!


Does it have antenna terminals with screws, or a coax plug, or both?

What's the make & model?

Bob
k5qwg

If it has 2 or 3 terminals (#3=gnd.), it is 200 ohms. If it has an original
coax connector it is 50 ohms. See EIA receiver standards for 1958.

--
Crazy George
Remove N O and S P A M imbedded in return address
"Edgar" wrote in message
...
Hello,
I've purchased an 1962 tube HF receiver. Well the problem is I don't know
exact antenna input impendence value of it. I use simple 40m. dipole on a
regular TV cable of 75 ohm. I would like to do some experiments with
random
wire, and 50 Ohm coax or 300 Ohm ladder line for dipole. Is there any
circuit that can help me to mach the impendence?

Thx,
Edgar
73!

The radio receiver is russian made "Volna-K" it means "Vawe-K" in english.
It has a coxial output.

Here is some more information about it:
Go to
http://babelfish.altavista.com/

and Translate a Web page form russian to english
http://www.cqham.ru/trx/volna.html

Tnx,
Edgar
73

Edgar wrote:
"---I don`t know exact antenna input impedance of it (the 1962 tube HF
receiver)."

The Radiotron Designer`s Handbook says on page 918:
"For use with domestic type receivers operating on the short wave band,
the standard dummy antenna is taken as being 400 ohms resistive, even
though the aerial reactance will not be zero across the tuning range, as
this gives an indication of average operating conditions."

Then on page 912 the book says:
"From the considerations detailed above, it can be seen that the coupled
circuit arrangement (an ordinary 2-winding antenna coil) of Fig. 23.2 is
generally satisfactory since it readily lends itself with minor
modifications, to applications using balanced or unbalanced aerial
systems."

Best regards, Richard Harrison, KB5WZI

Edgar wrote:
"The radio receiver is Russian made "Volna-K" it means "Wave-K" in
English."

I don`t know either Russian or English, but guess that there may be
similarities, as there are between Portuguese and Spanish which I do
speak. Portuguese and Spanish have many words in common but they often
have many differences in the most used words.

Thousands of times I`ve heard the station ID which sounded to me as:

"Radio Volna Europa, Vloss Volna Polska"

I always thought it must mean:

"Radio Free Europe, Voice of Free Poland"

Just a guess. I never looked it up nor asked any of the Polish exiles I
worked with.

Best regards, Richard Hsarrison, KB5WZI

Edgar wrote:

Hello,
I've purchased an 1962 tube HF receiver. Well the problem is I don't know
exact antenna input impendence value of it. I use simple 40m. dipole on a
regular TV cable of 75 ohm. I would like to do some experiments with random
wire, and 50 Ohm coax or 300 Ohm ladder line for dipole. Is there any
circuit that can help me to mach the impendence?

Edgar,
Since I can read and understand Russian I looked at the site you gave in
your post. They say that the antenna input us provided for a symmetrical
twin lead 200 ohms impedance. They aso say that it is a double
conversion receiver; the second If is 85 kHz giving rether good
selectivity. The stability of the receiver is rather poor, and the
anateurs used to use it as an IF amplifier of 2 MHz first IF. If you
want me to translate for you some more data, send me an e-mail. They
also say that any longer wire as an antenna will do. Best wishes,
Bozidar, 9a2hl

Edgar wrote:

Hello,
I've purchased an 1962 tube HF receiver. Well the problem is I don't know
exact antenna input impendence value of it. I use simple 40m. dipole on a
regular TV cable of 75 ohm. I would like to do some experiments with random
wire, and 50 Ohm coax or 300 Ohm ladder line for dipole. Is there any
circuit that can help me to mach the impendence?

Edgar,

Since I can understand and read Russian I looked at the site you
mentioned. They say that the antenna input has been forseen for a
symmetrical twin-lead 200 ohms impedance. They also add that any longer
wire would do. They also mention that the receiver has poor stability;
however it is a double mixing superhet, and the second IF is 85 kHz
which gives rather good selectivity. The Russian amateurs used to use it
as an IF amplifier at 2 MHz, so they standardly built a converter with a
crystal XO in it and got a very usable amateur receiver. If you need
some more translation, just send me an e-mail. Best wishes,
Bozidar, 9a2hl

On Tue, 25 Nov 2003 09:44:32 +0200, "Edgar" wrote:

The radio receiver is russian made "Volna-K" it means "Vawe-K" in english.
It has a coxial output.

Here is some more information about it:
Go to
http://babelfish.altavista.com/

and Translate a Web page form russian to english
http://www.cqham.ru/trx/volna.html

Tnx,
Edgar
73


Hi Edgar,

Bozidar has already identified the input Z (200 Ohms). As for the
rest of it, the schematic reveals it has a turret tuner (or barrel
tuner) for changing bands. Such a mechanism allows for tuning over
multiple bands to provide for both greater tuning resolution, and
linearity. The Tuning mechanism contains an antenna coupling filter
(following a general low pass filter with neon tube suppressor at the
input connector); two stages of Tuned RF amplification; and one Tuned
Mixer/Oscillator. The schematic is pretty rough, so I could be wrong
and it is one RF Amp, a Mixer, and an Oscillator. It may need
alignment for best service.

Almost any antenna longer than a whip (small wire dipole 10 - 20 feet
high) will do.

73's
Richard Clark, KB7QHC

Thank you all,
I can do understand Russian very little too:-( The problem is I am new to
all this technical radio stuff. I am an ordinary SWL for two years from LY
country:-), I started interesting in ham bands so I bought this radio to
explore them. Well as for AM listening the receiver do quite well, but for
ham band is worse. I decided to experiment with antenna to expand my
listening capabilities. So I came up to impedance question. I thought it is
very important. After your replies I try to do some random wire antenna test
first:-).

Thanks for your replies.
Your sincerely,
Edgar
73!

In article ,
says...
http://www.cqham.ru/trx/volna.html

cool looking radio...I didn't translate but looks like dual
conversion...serious rig.

At that era, (if my memory hasn't gone west) a standard receiving
antenna on *on this side of the pond* was a 400 ohm resister in series
with a 470 pf cap, that combo in parallel with a 1 uh inductor all in
series w/ a 200 ohm resistor...meaning it was purely resistive 300 ohms
at 7 mhz, capacitively reactive below and inductively reactive above.

Wx the comrades would have used the same standard I have no clue.