I have finally tracked down a copy of the original RG-21A/U specification, and have posted it in the Files section of this Group, in the Coaxial Cable folder. RG-21A/U became official on 07 September 1955, as MIL-C-17/14. Then, RG-21A/U was replaced by RG-222/U, AKA MIL-C-17/83, on 28 February 1958. RG-222/U was canceled on 12 August 1983, and its replacement was M17/162-00002, AKA MIL-C-17/162. Both RG-21A/U and RG-222/U are double-shielded and have a "high-resistance" center conductor, but M17/162-00002 has a silver-coated solid copper center conductor. It seems quite odd that a "linear attenuator" cable would be replaced by a cable that has negligible attenuation.
73, Eric Lemmon WB6FLY -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Doug Sent: Wednesday, March 24, 2010 8:47 PM To: [email protected] Subject: RE: [Repeater-Builder] RG21AU CABLE At 09:26 PM 24/03/2010, you wrote: >Doug, > > From what I have found, RG-21A/U cable is 53 ohm impedance, 0.339" outer >diameter, double silver-plated copper braid shields, and a solid center >conductor of "high resistance wire." The dielectric is solid polyethylene, >and the jacket is black PVC. If you have a sample of this wire, please >reveal what is printed lengthwise on the jacket. > >73, Eric Lemmon WB6FLY ---- Hi Eric. Well it has Plastoid Corportation RG-21/AU on the black jacket. It is stiff coax. You describe it very well. I sort of remember using something like this to reduce the power of an old Prog line unit... Here in Canada they didn't allow us to turn the power down, you had to use an attenuator. Thanks Eric Doug
