[TowerTalk] Selecting Coax connectors

Tue Sep 6 01:42:29 EDT 2016

As a "personal choice", my hands are no longer steady enough to prevent 
getting solder on the outside of the center pin so I'm relegated to 
using the crimp type although I'd not seen any for the DIN. I would add 
that I can now hold the solder with my left hand if a lot of movement 
isn't required.
I "would think" if the commercial guys are using crimp, it should be 
reliable enough.

OTOH I think this is a good place for long time users to chime in with 
their experiences.

73

Roger (K8RI)

On 9/5/2016 Monday 8:44 PM, Bob K6UJ wrote:
> Roger,
>
> Great overview on connectors !
> One thing that I am wondering about is whether or not to get the 
> solder type
> center pin on the DIN connectors.  I see them clamp or crimp style for 
> the outer shield and also
> solder or non solder on the center pin.  I like the crimp style outer 
> and clamp is fine too, but not sure
> if getting a non solder center pin is a concern.   Whats your view on 
> the center pin attachment ?
> I remember discussions here on Tower Talk in the past about center pin 
> creep in type N connectors.
> The DIN is a different animal though...........
>
> Bob
> K6UJ
>
> On 9/5/16 5:08 PM, Roger (K8RI) on TT wrote:
>> I see a lot of preferences from UHF, To :N: type, to DIN, but for the 
>> average ham, does it make a difference?
>>
>> Take UHF, essentially the design is crude and they are cheap! The 
>> loss figures are high, but those figures are for frequencies few hams 
>> ever approach and the connector specs say up to 300 MHz and 500 
>> volts.. On HF the loss is minuscule. The arguments are those figures 
>> add up and they do, but it's still a very small value. With SO2R and 
>> remote antenna switches, plus the rotator loops and pigtails to the 
>> antennas I've counted as many as ten connectors between the rig and 
>> antennas, but the loss was barely detectable. Impedance bumps? Yes, 
>> they are there, but what do the mean? Added up for the 160 through 10 
>> meter bands, they are insignificant. I can see where the reflections 
>> "might" make a difference with digital modes, but it's still very 
>> small.  The only down side I can see is the learning curve for the 
>> solder types.  "Probably" the average ham does a miserable job of 
>> soldering them, over heating the connector and coax when soldering 
>> the braid, turning the coax dielectric into a mass of goo, while 
>> getting solder on the exterior of the center conductor pin.
>>
>> Off brand UHF connectors: Many adherents say Amphenol 
>> http://www.amphenolrf.com/connectors/uhf.html  is the only way to go 
>> and they do have reasonably good quality control.  As I said at the 
>> beginning, the original connector design is crude, but it was 
>> designed long ago.  They are easy to make, so there are many off 
>> brand connectors of various qualities. Amphenol lists both Nickel and 
>> silver finish as well as a whole slew of dielectrics from Phenolic 
>> and Styrene, to Teflon and more.  The off brand stuff varies, but a 
>> good inspection by the Ham who knows what to look for, there are good 
>> ones out there.  The typical Ham would do better sticking with known 
>> brands, but with the UHF design, the important point is whether the 
>> particular connector will pass the test of time.  OTOH even 
>> top-of-the-line connectors are inexpensive and if you purchase very 
>> many, the discount makes them about the price of the stuff you see at 
>> the swaps..
>>
>> Installed according to the directions (braid on the inside and 
>> properly soldered), the connector will provide reasonable 
>> strength.       NOTE UHF connectors are not weatherproof!
>>
>> N-Type. Not for those running "high power". By high power, I'm nor 
>> referring to 1500 watts. 
>> http://www.amphenolrf.com/connectors/n-type.html  OK, so they 
>> represent less insertion loss with less impedance, but what do they 
>> gain us at 160 through 10?.  Amphenol lists them "These connectors 
>> are used in all systems where excellent RF and mechanical performance 
>> is critical."  I'm not sure by what they mean when they refer to 
>> mechanical performance, but I've never found the typical N-type 
>> connector I couldn't pull off the coax with my hands (crimp type 
>> excepted) In my experience, They have two limitations.  Mechanical 
>> strength and center pin migration are the problems I've seen.
>>
>> Mechanical strength is pretty much self explanatory. Center Pin 
>> Migration? On vertical runs, the center conductor in many, if not 
>> most coax cables will slowly move downward  This tends to pull the 
>> center pin, in on the top connector, and push the center pin out on 
>> the bottom connector. This doesn't happen with connectors where the 
>> center pin is captive.
>>
>> DIN (7-16) connectors. 
>> https://en.wikipedia.org/wiki/7/16_DIN_connector Is kinda like an 
>> N-connectors on steroids. The 7-16, or 7/16 is the size of the center 
>> pin (7 mm) and the ID of the outer connector (16 mm) They are still a 
>> bit on the expensive side and not for the ham who purchases 
>> connectors at swaps to save a buck, but " It is among the most widely 
>> used high power RF connectors in cellular network 
>> <https://en.wikipedia.org/wiki/Cellular_network> antenna systems." 
>> and "The 7-16 DIN connector out performs other non-flange options, 
>> such as N connectors <https://en.wikipedia.org/wiki/N_connector> or 
>> BNC connectors <https://en.wikipedia.org/wiki/BNC_connector>, when it 
>> comes to interference and intermodulation rejection or higher power 
>> handling at RF frequencies.^[1] 
>> <https://en.wikipedia.org/wiki/7/16_DIN_connector#cite_note-UTC-1>" 
>> (Quoted from the above Link)
>>
>> Adapters: Amphenol lists 689 adapters. Pages from 
>> http://www.amphenolrf.com/adapters.html However, other than the most 
>> common it's likely the distributor would need to special order them.
>>
>> Crimp, Vs solder. Other than requiring a specialized crimp tool, 
>> crimp connectors tend to be more uniform, faster to install, and 
>> mechanically stronger than the solder type.  Properly adjusted cable 
>> prep tools (strippers) really speed things up and present identical 
>> cable ends to the connectors with the proper dimensions. Nearly 
>> identical crimp tools can be found with widely varying prices.  One 
>> crimp tool with two sets of inserts can cover cables from RG-58 
>> through RG-8 (LMR-400) sizes. Depending on the vendor, nearly all 
>> connectors for these cables are available in solder or crimp versions.
>>
>> NOTE The RG designation has not been a specification for many years. 
>> It simply refers to cable sizes. Nothing more.
>>
>> So the question is, why would the average, or typical ham need 
>> anything other than the crimp, or solder, UHF connector?
>>
>> A SIDE NOTE: on weather proofing: There are several approaches to 
>> weatherproofing. One uses vinyl electrical tape wound sticky side out 
>> over the connectors, to keep the weatherproofing material (coax seal, 
>> various self vulcanizing tapes, and "flooded" heat shrink tubing) 
>> from sticking to the connector Flooded heat shrink tubing has a layer 
>> of hot melt glue on the inside. If you don't want the glue to stick 
>> to the connector, a film of Silicone grease or mold release agent, 
>> will allow for a seal without the glue sticking to the connector. 
>> Just don't get any on the coax jacket. Me?  I make sure it's all 
>> clean and bond to the whole works.
>>
>> By bonding to the coax jackets and the connectors, the flooded heat 
>> shrink tubing makes for a very strong mechanical connection.
>>
>> One other comment: In over 55 years as a ham, I've only seen two bad 
>> connectors from Amphenol. I can't say that  for the few "brand 
>> unknown", I've purchased from swaps.
>>
>> 73
>>
>> Roger (K8RI)
>>
>>
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73

Roger (K8RI)

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