There was a reference to "Silicone Caulk" for sealing the connector threads. I
think he meant Silicone grease. Silicone
grease is better for a number of reasons, and although some folks use Silicone
caulk on the outside of connectors, and to seal wire connections from coax to
wire antenna feed points, I recommend against it as there can be adverse
chemical reactions with copper wire and also silicone caulk will seem to adhere
to PVC and PE (many LMR's) outer jacket but in very short time the seal will
break down, letting water in.
Jim, K8RI's suggestion for sealing connectors using various waterproof (edit:
and definitely UV resistant) tape, or adhesive lined heat shrink (Jim refers
to "flooded" heat shrink, which is often the term but most often "adhesive
lined" is how it is sold) is an astute observation. DAVIS RF has AMP mil
spec cold fusion tape (no heat needed, no mess or stickiness when applying).
Bottom line: no matter what connector you use (even N connectors internally
sealed w/ rubber seals, which often works well for moisture resistance
(moisture resistance and WATER resistant are 2 very different aspects), for
true water resistance, and avoiding that system failure in the middle of the
rare DX contact attempt, or contest, or when it is at the top of the tower,
seal the connectors with waterproof sealing products.
Another observation: One contributor questions what feed thrus are available
for LMR 600 size cable. LMR 600 can be terminated with UHF, N's or DIN males
and suitable female/female feedthru "barrel" adaptors , or flange mount females
can be obtained for each type connector (without checking, the DIN flange
mounts might be difficult but if out there, I'd supply them).
Lastly: using adaptors: female to female barrels, male to female, right
angles, between series adaptors (such as N's to UHF's), etc etc: Don't fear
the old addage that adaptors increase your cable losses or cause adverse
impedance bumps. If good quality, as we sell, the max. insertion loss will be
only .200 dB AT THE MAX MUF for the type connector (UHF MUF is 300 MHz and N's
(most common) are 6 GHz, and the insertion loss to freqcy is linear, so
particularly at HF, the insertion loss is miniscule.
Note: UHF males for LMR-600 are quite expensive. Better to use N males and an
adaptor to UHF male.
I hope this is of some help,
73, Steve , K1PEK,
DAVIS RF Co., Div. of Orion Wire Co., Inc.
Wire, Cable, RF Connectors and wire aerial parts. LMR, Heliax, Eupen, etc.
Commercial / Military
Custom Cable Design
tel: 978-369-1738 Fax: 978-369-3484
On Jul 31, 2010, at 12:01 AM, email@example.com wrote:
> On 7/30/2010 3:01 PM, jimlux wrote:
>> K0DAN wrote:
>>> I have a variety of cables coming down the tower, including LMR600-U/F, all
>>> of which go into a NEMA box, then surge suppressors, shield grounding, etc.
>>> The box& cables have been there 10+ years, and as things break or change, I
>>> have found that it's handy to terminate the cables coming off the tower at
>>> ground level, add gender or other adaptors, run short pigtails into the NEMA
>>> box, then continue the runs to other antennas, the shack, etc.
>>> Yes, there is more need to weatherproof the splices, and there are slight
>>> impedance bumps& losses with the extra splices/connectors, however:
>>> a) you can get anything to fit your feedthrough's into the box
>>> b) If something fails or needs troubleshooting, it's easy to tap into or
>>> swap lines
> You could use 7-16 DIN or N if you want a more weather resistant connector.
> For that matter, maybe you could mount the protective device so the
> threaded part of the connector sticks out through the hole, and use
> silicone caulk to make it rain tight.
>> Or what about SO-239:SO-239 bulkhead feedthroughs? They're fairly
>> inexpensive, and you can run whatever kind of coax inside the NEMA box
>> that you want to. Granted, the connectors on the outside won't be
>> weather proof (since PL-259s aren't designed for it)
> Why not? You can wrap them with coax seal, tape, flooded heatshrink,
> or a combination. If the flooded heat shrink goes up onto the bulkhead
> connector it will fill the exposed threads with hot glue, thus making it
> water proof.
> Roger (K8RI)
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