Description

This cable is to connect an R-390 x to an antenna. 240 sold so far. F or the twinax antenna cable for the SP-600 , do an ebay search for 'SP600 twinax'. This listing is $4 more than the basic cable to allow you to request different choices for cable length and connector on the other end. Send me an ebay message (contact seller) first, if you'd like something different than the one pictured and described below. I will refund the unused portion when I send you the custom cable. Custom made cables available . -- SAVE $2 -- Request a used but excellent twinax connector instead of a new one. The connector cable shown is specifically made for the R390A, R391, and R390 Balanced Twin-Ax antenna jack connector with 2 female contacts on the receiver. If you are using a long or medium length of coax to feed these receivers, you should use the balanced antenna connection (low impedance), and not the 'unbalanced' connection (which is for a high impedance short antenna connection). I have constructed this cable to use the Twin-Ax connector using an amphenol Twin-Ax Plug, 82-5589-RFX or an AIM 27-9080 (they are the same as UG-421), by connecting the coax center conductor to the pin that goes into the right hand contact on the R390A (looking at the rear of the receiver). On the R390 and R391, it would be the top pin. The other pin connects to the coax shield and also to the connector body to provide chassis ground. The 125 ohm balanced antenna connection on these receivers is designed to work with impedances of 50 to 200 ohms without much of a mismatch. The loss is extremely small, so using a balun to overcome the imbalance would introduce more loss than without a balun. The least insertion loss available today in this type of balun would be about .5 db on the low frequency side, and up to 2.5 db on the high side. The maximum loss without a balun due to a mismatch on an R390A is about .3 db. Impedance matching in this range on a receiver is not very important. I will connect a 'clamp style' male BNC connector on the other end of the 'clamp style' Twin-Ax Plug using 35" of high quality RG-58/U with copper wire core and copper braided shield. If you purchase this without sending me a customizing e-mail first, this is what you will receive. I only use 'clamp style' connectors, unless requested otherwise. Since the connector is not 'crimped' and the shield not soldered, they are easily changed or reused. They do however cost a little more (which is included). If you would like a custom cable, your choices would normally be, but are not limited to: 1. No connector on the other end - save $2 2. A different length of coax - $0.70 per foot 3. A different connector on the other end: UHF male PL-259 (add $1), UHF female SO-239 ( add $1 ), Type N male (add $3), Type N female (add $2), BNC female (add $0), RCA male (all metal, add $1), other (ask). If you order a custom cable with different choices, I will need to send you information for the difference in the charges. So, after I respond to your Ebay message request with that information, you can decide whether to purchase this cable or not. If you purchase more than one cable at one time or previously, all the connectors may look different, but will function correctly. The shipping price listed is for the continental 48 US States only, outside will be more.