[Heath] Heathkit SB-644A, Remote VFO Cables

[Kenneth G. Gordon]

> On 10/8/2021 2:54 PM, Steven Feinsmith wrote:
>     coaxial cable. The original cable labeled as follows:
>     
>     300V  80 degree  FR-1  (UL)  AWN  STYLE  1436
>     
>     I searched for the specification for that cable. Unfortunately, there was almost no 
>     information such as 50-ohms?

I will bet that is RG-62, which Heathkit used to interconnect different bits such as the SB-300 
to the SB-400, etc.

I believe that stuff is 68 ohms.

The reason Heathkit used it was because it shows very much less attenutation than RG-58, 
but as mentioned, the impedance is of no real concern.

In your case, I would, like Chris, recommend that you simply use RG-58, although you 
COULD use RG-174 (50 ohms) if you wanted something far more flexible. The power levels 
are so low that using RG-174 wouldn't matter....although soldering it to an RCA connector 
would be more difficult.

I would certainly not use RG-8X. It is not necessary, and is too hard to use for what you need 
it for.

As for the RCA connectors, it turns out that Collins also used those extensively because they 
provide a much better match to 50 ohms than a PL-259/SO-239 does, and at power levels up 
to well over 100 watts, they work just fine. Of course, the ceramic-insulated ones are best.

The so-called "UHF" connector, however, does hold onto each other better because they are 
screwed together.

Ken W7EKB