All original cables were 38" long tip-to-tip.
The INJ and CAR OSC cables used a foam inner dielectric and phono
connectors with a white insulation. This cable measures 60 pF total
capacity.
All other cables used the standard for the day clear polyethelene inner
dielectric and phenolic (brown) insulated phono connectors and measures
~100 pF.
Original Drake INJ and CAR OSC Cables = 19 pF/ft = .160" o.d. (foam poly)
RG-62 = 93R = 13.5 pF/ft = 0.240" o.d.
RG-59 = 75R = 14.8 pF/ft = 0.242" o.d.
RG-6 = 75R = 16.2 pF/ft = 0.270" o.d.
RG-174= 50R = 30.8 pF/ft = 0.110" o.d.
Mic Cable (Belden 8410) = Hi-Z = 33 pf/ft = 0.160" o.d. (foam poly)
Mic Cable (Belden 8421) = Hi-Z = 16 pf/ft = 0.180" o.d. (foam poly)
R/S Audio Patch Cable = 28 pF/ft = 0.165" o.d. (poly)
The best choice is the Belden 8421 Audio cable from their "Brilliance"
line. It looks just like the other cables, and is very flexible. The
RG-62 is OK, but it is 50% larger and far less flexible. RG-62 is also
prone to shorting if bent over too small a radius, and is susceptible to
heat damage when soldering connectors. The best "feature" of RG-62 is
that it is often FREE, since there have been many miles of it pulled out
of old computer networks. Belden 8421 is available by the foot from ACK
Electronics in Atlanta. Other distributors have it as well, although
many require purchase of a full spool.
The only pertinent factor is the total capacity. Impedance and "loss"
are not important.
Any _reasonably low capacity_ coax will work if the units are cabled
together for the adjustment of the INJ trimmers.
The cable type ONLY affects the LEVEL of the PreMix signal, (5.645 MHz
ABOVE the transmit/receive frequency,) and a small DC control voltage
between the two. If the shunt capacity is too high, insufficient LO
level for the first mixer will reduce the sensitivity of the receiver
and the output power of the transmitter.
Some of the "commercial" cable mfrs use RG-59A, but it's a little larger
and also prone to shorting if bent over too tight a radius.
The ANT lead to the receiver is too short to matter, but you want good
shield integraty, which usually eliminates R/S cables.
The best connectors I've found are the Switchcraft 3502 plugs, available
from just about anyone, Digikey, Mouser, Allied, Newark and just about
any reputable parts place.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs
<www.k4oah.com>
J G wrote:
Hello Fellow Drake fans:
I came home from a recent hamfest with a C line. There were no
interconnect cables. This has been covered before, but I want to
verify (and clarify). A thread dated 12 July 2006 gave me the lengths
and the Belden number for the INJ cable.
Is it only the injection cable that should be Belden 8421? Can the
others be common (Radio Shack, etc.) audio cables? Would it be best to
use RG-58 for the antenna?
And, another question:
I have not been able to find phono connectors with a hollow tip. The
kind that the center conductor goes through. The best I have found
lately have a small solder eye terminal for both center and shield. It
used to be easy to find these. Now I have a wide variety of types I do
not care for due to my ordering and hoping they were what I want. If
you know of a place, please let me know. A part number would be good!
Thank you,
Jim
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