Re: 23cm warm cable

Phil Guttridge G3TCU

I find 0.25" semi-rigid (real RG401) gets warm at 400W on 23cm.

73, Phil. G3TCU

On 03/03/2021 22:55, Andy G4JNT via wrote:
To be a bit more scientific about it :

Loss in  .086 Simi Rigid is  0.73dB / metre at 1296MHz.   SO in a 100mm length, that's   1 - 10^(-.0073)   = 0.0167 of the input power dissipated.

At 100 Watts that's 1.7 Watts dissipated in 100mm of cable.   You'd expect it to be getting warm

On Wed, 3 Mar 2021 at 22:45, ian hope (2E0IJH) <ian@...> wrote:
I remember melting a Rg213 patch lead with a K2RIW, BTW if anyone's got a neglected one laying about PM me
Sent: Wednesday, March 03, 2021 at 10:33 PM
From: "Andy G4JNT" <andy.g4jnt@...>
To: "UK Microwaves" <>
Subject: Re: [UKMicrowaves] 23cm warm cable
You'd expect .086 SR to get warm at 100W of L-Band
Back in the days of playing with a K2RIW, I remember the thicker .141 SR gets warm at 400W of 432MHz
And the same stuff warms with 10W of 10GHz
You should be using .141 at that level / frequency
On Wed, 3 Mar 2021 at 21:18, militaryoperator via <> wrote:
Ok, my new 23cm 100W set seems to be working but noticed the cable from amp to isolator is getting warm, its blue mini bend, and the cable from ant relay to socket on case wall, semi-rigid (0.086) is also warm. 
I'm going N to sma adapter, sma mini-bend to sma iso, iso is sma o/p to sma to N adp into relay, N to sma adp then semi rigid to N chassis socket.
What else can I use? RG402?  I could use N type soldered to RG402 to sma for Amp to Iso and  Soldered N RG402 to N and use a N to N bulkhead I guess. That would remove a couple of adaptors.




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