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OT trying to identify "mystery" coax cable

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K6LMP

OT trying to identify "mystery" coax cable

I was browsing through the local Salvation Army Thrift Store (where I sometimes go looking for low-priced antique treasures), and stumbled across a 50-foot length of RG-8-type coax cable. At the asking price of $6.00, I couldn't pass it up.

It has Amphenol male "UHF" connectors. And absolutely NO markings on the cable itself indicating manufacturer or type. The OD of the cable varies from point to point, but averages about .405 inch, which puts it in the RG-8b family. It is quite flexible, and clearly stranded center conductor, not solid. Capacitance of the 50 foot cable was measured 1155 pF, or 23.1 pF per foot, which eliminates some RG-8 flavors that have 30 pF per foot. The only distinguishing feature of the cable is that there appears to be a wire would spiral-wise (1/2 turn per inch) outside the standard foil shield and under the exterior rubber sheath. I've never need that construction before on any RG-8 cable. (I haven't cut it open to verify the construction, because I don't want to have to de-solder and reconnect the Amphenol connector.)

I attached the cable to my dummy load and to the HF output of my K3. Keying the transmitter at 12 watts produces an SWR of 1.05:1 (external SWR meter) on all bands up to 6 meters, and continuity checks confirm that the cable has neither short circuit between shield and cable nor open circuit. In other words, it appears fit for duty.

Two questions;
1. Anything else I can or should do to check the cable and make sure it's OK to use? (Unfortunately, I do not own or have access to an antenna analyzer.)
2. Based on the "spiral winding" between the shield and outer coverk does anyone have an idea what specific cable this might be?

Thanks, and 73

Lew K6LMP

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AC7AC

Re: OT trying to identify "mystery" coax cable

CONTENTS DELETED

The author has deleted this message.

Mike WA8BXN

Re: OT trying to identify "mystery" coax cable

In reply to this post by K6LMP

Do you really mean a foil shield on the cable? Not sure I remember running
into any RG-8 cable with foil. Might give a clue to someone if it does have
it.

73 - Mike WA8BXN

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Re: OT trying to identify "mystery" coax cable

In reply to this post by K6LMP

I don't know what kind of cable it is Lew, but the lower capacity per foot
should make it better for VHF and lower the loss a bit. You might put your watt
meter at the dummy load end and measure the power out at 6 meters. If it is 9
or 10 watts, you have a good feed line so go for it, you have a bargain.
Willis 'Cookie' Cooke
K5EWJ

________________________________
From: Lew Phelps K6LMP <[hidden email]>
To: Elecraft Reflector <[hidden email]>
Sent: Wed, April 13, 2011 11:58:51 AM
Subject: [Elecraft] OT trying to identify "mystery" coax cable

I was browsing through the local Salvation Army Thrift Store (where I sometimes
go looking for low-priced antique treasures), and stumbled across a 50-foot
length of RG-8-type coax cable. At the asking price of $6.00, I couldn't pass it
up.

It has Amphenol male "UHF" connectors. And absolutely NO markings on the cable
itself indicating manufacturer or type. The OD of the cable varies from point to
point, but averages about .405 inch, which puts it in the RG-8b family. It is
quite flexible, and clearly stranded center conductor, not solid. Capacitance
of the 50 foot cable was measured 1155 pF, or 23.1 pF per foot, which eliminates
some RG-8 flavors that have 30 pF per foot. The only distinguishing feature of
the cable is that there appears to be a wire would spiral-wise (1/2 turn per
inch) outside the standard foil shield and under the exterior rubber sheath.
I've never need that construction before on any RG-8 cable. (I haven't cut it
open to verify the construction, because I don't want to have to de-solder and
reconnect the Amphenol connector.)

I attached the cable to my dummy load and to the HF output of my K3. Keying the
transmitter at 12 watts produces an SWR of 1.05:1 (external SWR meter) on all
bands up to 6 meters, and continuity checks confirm that the cable has neither
short circuit between shield and cable nor open circuit. In other words, it
appears fit for duty.

Two questions;
1. Anything else I can or should do to check the cable and make sure it's OK to
use? (Unfortunately, I do not own or have access to an antenna analyzer.)

2. Based on the "spiral winding" between the shield and outer coverk does
anyone have an idea what specific cable this might be?

Thanks, and 73

Lew K6LMP

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Bob Naumann W5OV

Re: OT trying to identify "mystery" coax cable

In reply to this post by Mike WA8BXN

Sounds like RG6 - 75 ohm.

> Do you really mean a foil shield on the cable? Not sure I remember running
> into any RG-8 cable with foil. Might give a clue to someone if it does
> have
> it.
>
> 73 - Mike WA8BXN
>
>
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Bob Naumann W5OV

Re: OT trying to identify "mystery" coax cable

In reply to this post by Mike WA8BXN

Nope - sorry! Not RG6.

RG11 - 75 ohm.

K5DNL

Re: OT trying to identify "mystery" coax cable

In reply to this post by K6LMP

Lew,

Look up RG9 I think it 52 OHM coax that has two shields.

73 Ken K5DNL

----------------------------------------------------------------------

--- On Wed, 4/13/11, Lew Phelps K6LMP <[hidden email]> wrote:

> From: Lew Phelps K6LMP <[hidden email]>
> Subject: [Elecraft] OT trying to identify "mystery" coax cable
> To: "Elecraft Reflector" <[hidden email]>
> Date: Wednesday, April 13, 2011, 11:58 AM
> I was browsing through the local
> Salvation Army Thrift Store (where I sometimes go looking
> for low-priced antique treasures), and stumbled across a
> 50-foot length of RG-8-type coax cable. At the asking price
> of $6.00, I couldn't pass it up.
>
> It has Amphenol male "UHF" connectors. And absolutely NO
> markings on the cable itself indicating manufacturer or
> type. The OD of the cable varies from point to point, but
> averages about .405 inch, which puts it in the RG-8b family.
> It is quite flexible, and clearly stranded center conductor,
> not solid. Capacitance of the 50 foot cable
> was measured 1155 pF, or 23.1 pF per foot, which eliminates
> some RG-8 flavors that have 30 pF per foot. The only
> distinguishing feature of the cable is that there appears to
> be a wire would spiral-wise (1/2 turn per inch) outside the
> standard foil shield and under the exterior rubber
> sheath. I've never need that construction before on
> any RG-8 cable. (I haven't cut it open to verify the
> construction, because I don't want to have to de-solder and
> reconnect the Amphenol connector.)
>
> I attached the cable to my dummy load and to the HF output
> of my K3. Keying the transmitter at 12 watts produces
> an SWR of 1.05:1 (external SWR meter) on all bands up to 6
> meters, and continuity checks confirm that the cable has
> neither short circuit between shield and cable nor open
> circuit. In other words, it appears fit for duty.
>
> Two questions;
> 1. Anything else I can or should do to check the cable and
> make sure it's OK to use? (Unfortunately, I do not own
> or have access to an antenna analyzer.)
> 2. Based on the "spiral winding" between the shield
> and outer coverk does anyone have an idea what specific
> cable this might be?
>
> Thanks, and 73
>
> Lew K6LMP
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
>

Jack Smith-6

Re: OT trying to identify "mystery" coax cable

RG9 (or its modern version, RG-214) has two woven shields of silver
plated copper.

Jack K8ZOA

On 4/13/2011 2:08 PM, Ken Roberson wrote:

> Lew,
>
> Look up RG9 I think it 52 OHM coax that has two shields.
>
> 73 Ken K5DNL
>
> ----------------------------------------------------------------------
>
>
> --- On Wed, 4/13/11, Lew Phelps K6LMP<[hidden email]> wrote:
>
>> From: Lew Phelps K6LMP<[hidden email]>
>> Subject: [Elecraft] OT trying to identify "mystery" coax cable
>> To: "Elecraft Reflector"<[hidden email]>
>> Date: Wednesday, April 13, 2011, 11:58 AM
>> I was browsing through the local
>> Salvation Army Thrift Store (where I sometimes go looking
>> for low-priced antique treasures), and stumbled across a
>> 50-foot length of RG-8-type coax cable. At the asking price
>> of $6.00, I couldn't pass it up.
>>
>> It has Amphenol male "UHF" connectors. And absolutely NO
>> markings on the cable itself indicating manufacturer or
>> type. The OD of the cable varies from point to point, but
>> averages about .405 inch, which puts it in the RG-8b family.
>> It is quite flexible, and clearly stranded center conductor,
>> not solid. Capacitance of the 50 foot cable
>> was measured 1155 pF, or 23.1 pF per foot, which eliminates
>> some RG-8 flavors that have 30 pF per foot. The only
>> distinguishing feature of the cable is that there appears to
>> be a wire would spiral-wise (1/2 turn per inch) outside the
>> standard foil shield and under the exterior rubber
>> sheath. I've never need that construction before on
>> any RG-8 cable. (I haven't cut it open to verify the
>> construction, because I don't want to have to de-solder and
>> reconnect the Amphenol connector.)
>>
>> I attached the cable to my dummy load and to the HF output
>> of my K3. Keying the transmitter at 12 watts produces
>> an SWR of 1.05:1 (external SWR meter) on all bands up to 6
>> meters, and continuity checks confirm that the cable has
>> neither short circuit between shield and cable nor open
>> circuit. In other words, it appears fit for duty.
>>
>> Two questions;
>> 1. Anything else I can or should do to check the cable and
>> make sure it's OK to use? (Unfortunately, I do not own
>> or have access to an antenna analyzer.)
>> 2. Based on the "spiral winding" between the shield
>> and outer coverk does anyone have an idea what specific
>> cable this might be?
>>
>> Thanks, and 73
>>
>> Lew K6LMP
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
> ______________________________________________________________
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> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
>

Geoffrey Mackenzie-Kennedy

Re: OT trying to identify "mystery" coax cable

In reply to this post by K6LMP

Lew, it might be some type of armoured coax. In one type, which IIRC goes by
the name of Armadilo, the coax is encased in a flexible metal tube. When the
flexible tube is covered by a non-metallic jacket, the armour feels like a
single wire wound spiral-wise - and 1/2 turn per inch sounds about right.

Again IIRC both 50 ohm and 75 ohm armoured coax of this type is (or was)
manufactured.

73,
Geoff
GM4ESD

Lew Phelps K6LMP wrote on April 13, 2011 at 17:58 +0100:

>I was browsing through the local Salvation Army Thrift Store (where I
>sometimes go looking for low-priced antique treasures), and stumbled across
>a 50-foot length of RG-8-type coax cable. At the asking price of $6.00, I
>couldn't pass it up.
>
> It has Amphenol male "UHF" connectors. And absolutely NO markings on the
> cable itself indicating manufacturer or type. The OD of the cable varies
> from point to point, but averages about .405 inch, which puts it in the
> RG-8b family. It is quite flexible, and clearly stranded center conductor,
> not solid. Capacitance of the 50 foot cable was measured 1155 pF, or
> 23.1 pF per foot, which eliminates some RG-8 flavors that have 30 pF per
> foot. The only distinguishing feature of the cable is that there appears
> to be a wire would spiral-wise (1/2 turn per inch) outside the standard
> foil shield and under the exterior rubber sheath. I've never need that
> construction before on any RG-8 cable. (I haven't cut it open to verify
> the construction, because I don't want to have to de-solder and reconnect
> the Amphenol connector.)

<snip>

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donhall161

Re: OT trying to identify "mystery" coax cable

In reply to this post by Jack Smith-6

RG214 is NOT modern RG9, but rather is ruggedized RG8. Check your friend
Google.

73 Don K5AQ

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George Dubovsky

Re: OT trying to identify "mystery" coax cable

Nope, the original poster is correct. RG214 is the replacement for RG9 -
both double-braid, same connectors...

73,

geo - n4ua

On Wed, Apr 13, 2011 at 2:50 PM, donhall161 <[hidden email]>wrote:

> RG214 is NOT modern RG9, but rather is ruggedized RG8. Check your friend
> Google.
>
> 73 Don K5AQ
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
>

K6LMP

Re: OT trying to identify "mystery" coax cable

In reply to this post by K5DNL

Okey, folks. Thanks for all the good input. Responding to several posted queries, I've gathered additional information:

1. I peeled away a sliver of the outer rubber insulation to inspect the shield. It's tinned copper braid over foil, which could be any of a number of RG-8 family cables.

2. Connecting the SWR/wattmeter at the "far" end of the cable shows that transmission loss is miniscule; at both 6 meters and 10 meters, I can't discern a difference in the needle position on the SWR/wattmeter. On 10 meters is's 12 watts. On 6 meters it's about 8.8, which is all that the K3 puts out on 6 meters.

3. SWR is 1.05:1 on 10 meters, and 1.5:1 on 6 meters, but I think this is the dummy load, not the coax. I get the same readings when I connect the dummy load to the wattmeter with a three foot section of Cable X-pert RG-8 foam insulation cable.

4. I'm pretty sure it's not RG-9, as someone suggested. Both the diameter and the capacitance per foot are much more in the RG-8 family than RG-9 (spec. .420 diameter, vs. measured .405 which is right on target for RG-8, and capacitnce of 23.1 pF per foot, vs. specified 30.0 for RG-9.

5. I'm certain that it's not 75 ohm cable, because of the low SWR on every band through 10 meters.

In one sense, I guess it doesn't matter, since I know enough about the cable to put it to good use. The only missing data that might be useful under some circumstances would be the Velocity Factor.

Thanks for all your input.

Lew K6LMP

>
> --- On Wed, 4/13/11, Lew Phelps K6LMP <[hidden email]> wrote:
>
>> From: Lew Phelps K6LMP <[hidden email]>
>> Subject: [Elecraft] OT trying to identify "mystery" coax cable
>> To: "Elecraft Reflector" <[hidden email]>
>> Date: Wednesday, April 13, 2011, 11:58 AM
>> I was browsing through the local
>> Salvation Army Thrift Store (where I sometimes go looking
>> for low-priced antique treasures), and stumbled across a
>> 50-foot length of RG-8-type coax cable. At the asking price
>> of $6.00, I couldn't pass it up.
>>
>> It has Amphenol male "UHF" connectors. And absolutely NO
>> markings on the cable itself indicating manufacturer or
>> type. The OD of the cable varies from point to point, but
>> averages about .405 inch, which puts it in the RG-8b family.
>> It is quite flexible, and clearly stranded center conductor,
>> not solid. Capacitance of the 50 foot cable
>> was measured 1155 pF, or 23.1 pF per foot, which eliminates
>> some RG-8 flavors that have 30 pF per foot. The only
>> distinguishing feature of the cable is that there appears to
>> be a wire would spiral-wise (1/2 turn per inch) outside the
>> standard foil shield and under the exterior rubber
>> sheath. I've never need that construction before on
>> any RG-8 cable. (I haven't cut it open to verify the
>> construction, because I don't want to have to de-solder and
>> reconnect the Amphenol connector.)
>>
>> I attached the cable to my dummy load and to the HF output
>> of my K3. Keying the transmitter at 12 watts produces
>> an SWR of 1.05:1 (external SWR meter) on all bands up to 6
>> meters, and continuity checks confirm that the cable has
>> neither short circuit between shield and cable nor open
>> circuit. In other words, it appears fit for duty.
>>
>> Two questions;
>> 1. Anything else I can or should do to check the cable and
>> make sure it's OK to use? (Unfortunately, I do not own
>> or have access to an antenna analyzer.)
>> 2. Based on the "spiral winding" between the shield
>> and outer coverk does anyone have an idea what specific
>> cable this might be?
>>
>> Thanks, and 73
>>
>> Lew K6LMP
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>

W6ODJ

Re: OT trying to identify "mystery" coax cable

Lew,

LMR-400 has 0.405 inches jacket diameter and has braid over a bonded foil. And I mean bonded. Almost impossible to remove. It is also very low loss and comes in either solid or stranded center conductor versions. If that's what it is, congratulations.

73,
Oliver
W6ODJ

On Apr 13, 2011, at 3:01 PM, Lew Phelps K6LMP wrote:

> Okey, folks. Thanks for all the good input. Responding to several posted queries, I've gathered additional information:
>
> 1. I peeled away a sliver of the outer rubber insulation to inspect the shield. It's tinned copper braid over foil, which could be any of a number of RG-8 family cables.
>
> 2. Connecting the SWR/wattmeter at the "far" end of the cable shows that transmission loss is miniscule; at both 6 meters and 10 meters, I can't discern a difference in the needle position on the SWR/wattmeter. On 10 meters is's 12 watts. On 6 meters it's about 8.8, which is all that the K3 puts out on 6 meters.
>
> 3. SWR is 1.05:1 on 10 meters, and 1.5:1 on 6 meters, but I think this is the dummy load, not the coax. I get the same readings when I connect the dummy load to the wattmeter with a three foot section of Cable X-pert RG-8 foam insulation cable.
>
> 4. I'm pretty sure it's not RG-9, as someone suggested. Both the diameter and the capacitance per foot are much more in the RG-8 family than RG-9 (spec. .420 diameter, vs. measured .405 which is right on target for RG-8, and capacitnce of 23.1 pF per foot, vs. specified 30.0 for RG-9.
>
> 5. I'm certain that it's not 75 ohm cable, because of the low SWR on every band through 10 meters.
>
> In one sense, I guess it doesn't matter, since I know enough about the cable to put it to good use. The only missing data that might be useful under some circumstances would be the Velocity Factor.
>
> Thanks for all your input.
>
> Lew K6LMP
>
>>
>> --- On Wed, 4/13/11, Lew Phelps K6LMP <[hidden email]> wrote:
>>
>>> From: Lew Phelps K6LMP <[hidden email]>
>>> Subject: [Elecraft] OT trying to identify "mystery" coax cable
>>> To: "Elecraft Reflector" <[hidden email]>
>>> Date: Wednesday, April 13, 2011, 11:58 AM
>>> I was browsing through the local
>>> Salvation Army Thrift Store (where I sometimes go looking
>>> for low-priced antique treasures), and stumbled across a
>>> 50-foot length of RG-8-type coax cable. At the asking price
>>> of $6.00, I couldn't pass it up.
>>>
>>> It has Amphenol male "UHF" connectors. And absolutely NO
>>> markings on the cable itself indicating manufacturer or
>>> type. The OD of the cable varies from point to point, but
>>> averages about .405 inch, which puts it in the RG-8b family.
>>> It is quite flexible, and clearly stranded center conductor,
>>> not solid. Capacitance of the 50 foot cable
>>> was measured 1155 pF, or 23.1 pF per foot, which eliminates
>>> some RG-8 flavors that have 30 pF per foot. The only
>>> distinguishing feature of the cable is that there appears to
>>> be a wire would spiral-wise (1/2 turn per inch) outside the
>>> standard foil shield and under the exterior rubber
>>> sheath. I've never need that construction before on
>>> any RG-8 cable. (I haven't cut it open to verify the
>>> construction, because I don't want to have to de-solder and
>>> reconnect the Amphenol connector.)
>>>
>>> I attached the cable to my dummy load and to the HF output
>>> of my K3. Keying the transmitter at 12 watts produces
>>> an SWR of 1.05:1 (external SWR meter) on all bands up to 6
>>> meters, and continuity checks confirm that the cable has
>>> neither short circuit between shield and cable nor open
>>> circuit. In other words, it appears fit for duty.
>>>
>>> Two questions;
>>> 1. Anything else I can or should do to check the cable and
>>> make sure it's OK to use? (Unfortunately, I do not own
>>> or have access to an antenna analyzer.)
>>> 2. Based on the "spiral winding" between the shield
>>> and outer coverk does anyone have an idea what specific
>>> cable this might be?
>>>
>>> Thanks, and 73
>>>
>>> Lew K6LMP
>>>
>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>>
>
> ______________________________________________________________
> Elecraft mailing list
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