BAP wrote:

Where is the empirical or engineering data to support this conclusion?

Collins did do the frequency sweeps -- and it out performed many of the
alternatives at that time --
if it didn't Art Collins would have never used the connector (BNC was
available at the time).

Look at it as a simple tube... look at the outside diameter of the shield
and the inside diameter of the center conductor and plug and chug using
the formulae in the ITT Radio Engineer's Handbook for coaxial conductors.
You get something around 95 ohms characteristic for the front part of the
connector (from the insulator forward). The back part of the connector
is less important but ou have an additional discontinuity from the ring
around the insulator.

Say, didn't the Heathkit "lunchbox" AM transceivers use RCA phono
connectors as an antenna conection? Those lunchboxes operated into low
impedance 50 ohm loads all the way up to 148 mcs.

Yup! And the truth is, you can away with pretty lousy connectors in
most antenna applications. But put a pulse generator and a scope in
place of the transmitter and you'll see discontinuities at the connector
points.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"tjbitt" wrote in message
oups.com...
Hi all, my name is Ted (KQ4MZ) and I just came into posession of a
Drake R4-C receiver which I intend to build a Drake station from. For
now I just plan to use this as an extra receiver. My question is how
can I connect a coax to the antenna jack on the back of the receiver? I
have never owned any older tube gear aside from old swl radios and have
never seen a phono plug type jack for an antenna. Can I solder the
center conductor of the coax to the pin on a male phono plug and the
braid to the body of the plug? Any help would be most appreciated. I
want to be able to connect the Drake into an antenna switch that I have
all my other rigs connected to . Thanks again for any and all
thoughts.
Ted---KQ4MZ


Ted -

The usage of Phono (RCA) jack for RECEIVERS and some QRP transceivers was
very common in 1950s -- 1980s --- Collins S-Line, Heathkit and Drake.

I own a Drake R-4C --- that I acquired from an estate earlier this year
This unit has required a significant amount of "clean-up" which I am still
doing -- it was a daily user radio and owner appears to have been a smoker.

RECOMMEND:

1. BUILD a small (~ 3 feet) coax patch cable (RG-58-U) or 8X with a phono
(RCA) jack -- one end to connect to Drake R-4C and the connector used for
your antenna switch on the other. IF you don't have these skills -- most
amateur radio service departments and Cable-X-Perts are happy to build this
for you.

2. DO NOT hack or try to change that Drake R-4C connector. The phono jack
field -- this 6 in-line phono connectors on a phenolic board on back panel -
is UNOBTAINIUM. I have personally talked to both H.H. Smith and
Switchcraft -- damage that -- and you would have to fabricate an entire
replacement.

2A. I actually had to disassemble and repair the antenna and speaker jacks
in that field last week --- the former owner had damaged the connectors. 2
hours of labor and some MAAS metal cleaning polish and these 2 jacks are
almost back to factory new -- I was lucky the damage was not more extensive.

You should have jumpers for the MUTE, PTO Lamp on back panel and a jumper
for 7-pin socket inside (if you have no noise blanker installed).

Greg, w9gb

Thanks for the suggestions. I ordred an rca adapter plug today. Do I
need the jumpers for mute PTO lamp etc if I'm using the R4C as a
receiver only ---no connection to transmitter? Hate to be a dummy but
these older radios are completely new to me. Thanks agn for the
help---Ted --KQ4MZ
w9gb wrote:
"tjbitt" wrote in message
oups.com...
Hi all, my name is Ted (KQ4MZ) and I just came into posession of a
Drake R4-C receiver which I intend to build a Drake station from. For
now I just plan to use this as an extra receiver. My question is how
can I connect a coax to the antenna jack on the back of the receiver? I
have never owned any older tube gear aside from old swl radios and have
never seen a phono plug type jack for an antenna. Can I solder the
center conductor of the coax to the pin on a male phono plug and the
braid to the body of the plug? Any help would be most appreciated. I
want to be able to connect the Drake into an antenna switch that I have
all my other rigs connected to . Thanks again for any and all
thoughts.
Ted---KQ4MZ


Ted -

The usage of Phono (RCA) jack for RECEIVERS and some QRP transceivers was
very common in 1950s -- 1980s --- Collins S-Line, Heathkit and Drake.

I own a Drake R-4C --- that I acquired from an estate earlier this year
This unit has required a significant amount of "clean-up" which I am still
doing -- it was a daily user radio and owner appears to have been a smoker.

RECOMMEND:

1. BUILD a small (~ 3 feet) coax patch cable (RG-58-U) or 8X with a phono
(RCA) jack -- one end to connect to Drake R-4C and the connector used for
your antenna switch on the other. IF you don't have these skills -- most
amateur radio service departments and Cable-X-Perts are happy to build this
for you.

2. DO NOT hack or try to change that Drake R-4C connector. The phono jack
field -- this 6 in-line phono connectors on a phenolic board on back panel -
is UNOBTAINIUM. I have personally talked to both H.H. Smith and
Switchcraft -- damage that -- and you would have to fabricate an entire
replacement.

2A. I actually had to disassemble and repair the antenna and speaker jacks
in that field last week --- the former owner had damaged the connectors. 2
hours of labor and some MAAS metal cleaning polish and these 2 jacks are
almost back to factory new -- I was lucky the damage was not more extensive.

You should have jumpers for the MUTE, PTO Lamp on back panel and a jumper
for 7-pin socket inside (if you have no noise blanker installed).

Greg, w9gb

tjbitt wrote:
Thanks for the suggestions. I ordred an rca adapter plug today. Do I
need the jumpers for mute PTO lamp etc if I'm using the R4C as a
receiver only ---no connection to transmitter? Hate to be a dummy but
these older radios are completely new to me. Thanks agn for the
help---Ted --KQ4MZ

Hi Ted,

One note, on some of these radios there isn't enough room on the inside
of the chassis for the long center pin (eg. original) RCA phono plug
to fit. I don't know if the Drake is in this group. You should take
a peek inside the chassis, and see if a protruding pin will get too
close to anything.

If you do find this to be the case, you can easily fix the problem
with a pair of diagonal cutters. Basically, you crimp the center pin
with the cutters a little bit, and rotate a few degrees, and do it again.
Just a little at a time, until the excess pin drops off. This rolls
the end over like the original, and makes soldering easier.

-Chuck

"Chuck Harris" wrote in message
...
tjbitt wrote:
Thanks for the suggestions. I ordred an RCA (phono) adapter plug today.
Do I
need the jumpers for mute PTO lamp etc if I'm using the R4C as a
receiver only ---no connection to transmitter? Hate to be a dummy but
these older radios are completely new to me. Thanks agn for the
help---Ted --KQ4MZ

Hi Ted,

One note, on some of these radios there isn't enough room on the inside
of the chassis for the long center pin (eg. original) RCA phono plug
to fit. I don't know if the Drake is in this group. You should take
a peek inside the chassis, and see if a protruding pin will get too
close to anything.

If you do find this to be the case, you can easily fix the problem
with a pair of diagonal cutters. Basically, you crimp the center pin
with the cutters a little bit, and rotate a few degrees, and do it again.
Just a little at a time, until the excess pin drops off. This rolls
the end over like the original, and makes soldering easier.

-Chuck

Ted -

In addition to Chuck's suggestion -- you will find that SOME of the phono
(RCA) to BNC adapters are a "bit wide" and crowd the phono jack for the
Speaker. I have 2 and I use the narrow one on the Drake R-4C.
====
To answer your other 2 questions.
I also operate my Drake R-4C as a stand alone receiver.

The MUTE and PTO lamp jumpers are needed -- when the receiver is NOT paired
with the matching Drake TX-4C.

The MUTE is "open" when the TX-4C transmits and closed on receiver (hence
the need for the jumper).
PTO Lamp is "open" when the TX-4C PTO is being used and closed when the
R-4C PTO is being used --- in a transceive configuration.

Now, you will find some operators solder a wire jumper inside the receiver
(a practice I discourage -- and had to remove from this estate item). These
jumpers are very easy to make. I use a blank RCA plug - solder a wire to
center pin then wrap other end around the location designated for shield or
other conductor -- very neat.
====
Lastly, you also need the jumper plug in the noise blanker socket -- IF it
is not present. Again, the OM that had this receiver before me soldered the
jumper to the bottom of that socket (bad form).

You have two options for the 7 pin plug. You can purchase Don Garrett's
(WA9TGT) solution
http://www.wa9tgt.com/Drake_R4C_4NB_Plug.html

OR purchase a 7-pin plug with screw on back from Leed's Radio (Brooklyn, NY)
and wire the 2 jumpers inside that plug.
7-pin miniature plug - Fits sockets for 1L6, 6AU6 etc good for making tube
adapters and test jigs with screw on back shell - NOS $4.00
http://www.leedselect.com/parts-sockets.html

New Drake blue filters?
http://www.wa9tgt.com/Dial_Filter_Page.html

or very well stocked hobby shops in .01 and .02 plastic sheets
http://www.midwestproducts.com/catal...d=19&sa2_id=21

w9gb

"tjbitt" wrote in message
oups.com...
Thanks for the suggestions. I ordred an rca adapter plug today. Do I
need the jumpers for mute PTO lamp etc if I'm using the R4C as a
receiver only ---no connection to transmitter? Hate to be a dummy but
these older radios are completely new to me. Thanks agn for the
help---Ted --KQ4MZ

I would get a good copy of the manual you need - Bob Sherwood has good
copies as well as a couple of the other manual suppliers (be selective).

BTW, there were 4 major changes during the Drake R-4C production run.

Wayne Montague, VE3EFJ compiled this information (below) and believes it to
be accurate, BUT not necessarily a complete dossier on the Drake R-4C
changes over its entire production run.
This is his latest update.
a.. R-4C ser no above 16121
Revision date - Feb 1973
All mixer tubes 6HS6. First and 3rd mixers cathode injected. Second mixer
is a dual gate MOSFET. The IF chain following the first crys- tal filter is
6BA6 1st IF, Noise blanker and then 2nd mixer. 4 posi- tion filter select.


b.. R-4C ser no above 18726
Revision date - March 1974
All mixer tubes 6HS6. First and 3rd mixers cathode injected. Second mixer
is a 6BE6 with a JFET (2N5949) buffer. 5 position crystal filter selection.
3 diodes in series across the S Meter to compress the meter range. 2 S Meter
zero pots were employed - one internal and one external.


c.. R-4C ser no above 21000
Revision date - Nov 1974
All mixer tubes 6EJ7. First and 3rd mixers grid injected. Second mixer is
a 6BE6 with an JFET (2N5950) buffer. 5 position crystal filter selection.
Some intermediate models in this transition period may not have installed
the new tapped IF transformer, T7C.


d.. R-4C ser no above 25900
Revision date - Jan 1976
All mixer tubes 6EJ7. First and 3rd mixers grid injected. Second mixer is
a 6BE6 with an JFET (2N5950) buffer. 5 position crystal filter selection.
T7C IF transformer. Very little electronic difference to the above model
except a 125 volt zener diode at the junction of R12 and R13 (regulated B+
to the plate of the 6BE6 mixer).

This could be the latest model in the series before production was halted.
From the schematic, the differences between this model and the 21000
previous is little.

It should be stated that the PL-259, a favorite of the ham world, is not a
constant impedance, either. Some hams go nuts if they see you use one of
those on 2 meters or higher. However, it is simple enough to calculate the
impedance bump at a particular frequency simply by determining the impedance
(using the ratio of diameters and the length of the connection), then
determining what that bump is at a particular frequency.

I did that once, to show a friend that he should not lose sleep over the
connector. It is like inserting a 1" length of 75 ohm coax in a 50 ohm
line. Remember that 50 ohm coax is not necessarily 50 ohms. It is a
nominal impedance, which means it might be 50 ohms, or 52 ohms or even 53
ohms. So, if you are worried about the connector, you should measure the
coax to see what impedance you really want.

RCA and GE both used RCA connectors (commonly called phono plugs) at 450
MHz.

Colin K7FM

COLIN LAMB wrote:
It should be stated that the PL-259, a favorite of the ham world, is not a
constant impedance, either. Some hams go nuts if they see you use one of
those on 2 meters or higher. However, it is simple enough to calculate the
impedance bump at a particular frequency simply by determining the impedance
(using the ratio of diameters and the length of the connection), then
determining what that bump is at a particular frequency.

PL-259 _is_ constant impedance, it's just not exactly 50 ohms. But it's
closer to 50 ohms than the RCA is.

I did that once, to show a friend that he should not lose sleep over the
connector. It is like inserting a 1" length of 75 ohm coax in a 50 ohm
line. Remember that 50 ohm coax is not necessarily 50 ohms. It is a
nominal impedance, which means it might be 50 ohms, or 52 ohms or even 53
ohms. So, if you are worried about the connector, you should measure the
coax to see what impedance you really want.

Not to mention measuring the antenna! But with coax, the number in the
manufacturer's catalogue is probably correct (but in a lot of cases it
is NOT the same as the number in the Radio Guide!)
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"tjbitt" wrote in message
oups.com...
Hi all, my name is Ted (KQ4MZ) and I just came into
posession of a
Drake R4-C receiver which I intend to build a Drake
station from. For
now I just plan to use this as an extra receiver. My
question is how
can I connect a coax to the antenna jack on the back of
the receiver? I
have never owned any older tube gear aside from old swl
radios and have
never seen a phono plug type jack for an antenna. Can I
solder the
center conductor of the coax to the pin on a male phono
plug and the
braid to the body of the plug? Any help would be most
appreciated. I
want to be able to connect the Drake into an antenna
switch that I have
all my other rigs connected to . Thanks again for any and
all
thoughts.


Ted---KQ4MZ
Ted, do you have a manual for this thing. If not there
is one on-line at:
http://bama.edebris.com/manuals/drake/r4c/
Probably pretty low res. There may be a better one
somewhere, a Google search should find it.


--
---
Richard Knoppow
Los Angeles, CA, USA

"tjbitt" wrote in message
oups.com...
Hi all, my name is Ted (KQ4MZ) and I just came into posession of a
Drake R4-C receiver which I intend to build a Drake station from. For
now I just plan to use this as an extra receiver. My question is how
can I connect a coax to the antenna jack on the back of the receiver? I
have never owned any older tube gear aside from old swl radios and have
never seen a phono plug type jack for an antenna. Can I solder the
center conductor of the coax to the pin on a male phono plug and the
braid to the body of the plug? Any help would be most appreciated. I
want to be able to connect the Drake into an antenna switch that I have
all my other rigs connected to . Thanks again for any and all
thoughts.
Ted---KQ4MZ


Ted,

Adobe Acrobat of the manual is available from N2CKH
http://www.n2ckh.com/library.htm

w9gb