Woody -
All original cables were 38" long tip-to-tip.
The INJ, (and CAR OSC in the C-Line, 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 measure ~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. N7IOH, another list member, had some at one
time that he was selling by the foot.
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 integrity, 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, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
Woody wrote:
/Gentlemen, I have a R4B & T4XB combo that I have had for many years and have never used except
for the R4B. Now that I'm playing with my Drakes again I have decided to use them or at least try.
Would it be better to buy the injection and other cables or make my own, if so what would be the
best cable to use and what are the length's. Where would be the best place to get them, I see some
advertised on Ebay. Any help would as always be //appreciated, and of course some of you know "I'm
Dumb as a Rock" on some of this, but I'm a Happy Rock!!
/
Thanks
"Woody"
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