?

I have seen this before also. We have had almost no winter this year except for the cold spell, so little in fact that the spring bulbs are coming up, and by thornless domestic Blackberry has a shoot 6 inches long, which oddly, the sub zero cold did not kill - weird! The cold detuned my 6 band fan dipole, and I was fortunate to have a tuner.

I think that the shrinkage in cold versus warm metals is likely just enough, especially on antennas with a high Q, to detune them in a hurry.

I think the 7K has what some call a "fold back circuit", a design where the radio at more than 1.5:1 SWR starts cutting back power, such that at a certain SWR it has virtually no output, but I wouldn't want to test it. Too many horror stories about the 7k burning finals...

I have a radio with a tuner, but rarely use it, since I normally use an all band 125' balanced center fed doublet, which few in-rig tuners could handle. I have one tuner for the shack, an MFJ-993B, and another, an LDG AT100ProII that is used for the shack and mobile/portable.

A good rain can also detune an antenna, coupling the rope to the tree or other support, effectively lengthening the antenna dramatically.

73 de KC4BO

Alex Netherton

On Mon, Jan 13, 2014 at 2:25 PM, Stanley Brannan <sbrannan@...> wrote:

?

One of the things I found out during the recent cold spell was that icing can dramatically alter the resonance and SWR of many types of antenna. I have a multi-band inverted V, an end-fed Pars and a multi-band vertical.

I was trying to demonstrate a small FT-817 QRP rig, and since I did not have any antenna tuner, I used one of my SWR meters, the AA-54 to make sure the SWR would be acceptable. I was shocked by the SWR in all of the Ham bands I was planning to use was very high, and not even tunable my radios with a built in tuner.

I went to broad sweep mode and found the ice or moisture hat moved the SWR point of resonance way out of band. Usually outside the bottom frequencies in the band. So far out my ICOM 7600 tuner could not get an acceptable match.

I left the radios off for a week and after a warm period where the snow and ice were melted, I rechecked all the antennas on all the bands and there was not long-term damage, and they center of the resonant frequencies was exactly where I had set it before.

When it is super cold and the snow is keeping you home from work, it is easy to get the urge to fire up the radios and kill some time rag chewing. But if the antennas are wet, or have been exposed to a cold snap with freezing rain or ice on the trees and lines, you should check your SWR carefully before tuning up.

My ICOM 7000 is set up for quick mobile installation using a 12v battery so I don't have to deal with wiring it into the cars electrical system and a Little Tarheel screwdriver antenna. I can also use it portable and I have it set up in a GO BOX with a matching antenna tuner and a bag of antenna options. I'm hoping to come up with an antenna option for my plane someday, but with a pressurized cabin it is hard to get a connection to an external antenna.

I have always babied my 7000 because of the lack of a built-in tuner. It is a lot of radio in a VERY small package and I would assume it has heat issues if used heavily at max output. My radio works great, and I love the configuration in the Go Box. If you set up at a school or park, you can put the rig box on a park table or use the tailgate of the vehicle and the Tarheel antenna does a great job if you don't want to string up a Pars End Fed antenna.

I rig my antenna feed with a switch option to connect it to an SWR meter with the flick of a switch. This allows me to make sure that before I try to get a tuner match that the antenna has a low SWR in the band I am planning to use.

This is key with Tarheel, tunable screwdriver antenna. It is so much easier to get it set up correctly by switching to a small SWR measurement device like the AA-54 or IP-30z from

Overheating your 7000 is probably much easier if you are driving a high SWR antenna situation. So make sure your antennas are in tune for the band you plan to use.

I may try to post some additional photos of my Icom-7000 set-up, if I can find them on my computer!!!

Stan Brannan, WJ0E

?

One of the things I found out during the recent cold spell was that icing can dramatically alter the resonance and SWR of many types of antenna. I have a multi-band inverted V, an end-fed Pars and a multi-band vertical.

I was trying to demonstrate a small FT-817 QRP rig, and since I did not have any antenna tuner, I used one of my SWR meters, the AA-54 to make sure the SWR would be acceptable. I was shocked by the SWR in all of the Ham bands I was planning to use was very high, and not even tunable my radios with a built in tuner.

I went to broad sweep mode and found the ice or moisture hat moved the SWR point of resonance way out of band. Usually outside the bottom frequencies in the band. So far out my ICOM 7600 tuner could not get an acceptable match.

I left the radios off for a week and after a warm period where the snow and ice were melted, I rechecked all the antennas on all the bands and there was not long-term damage, and they center of the resonant frequencies was exactly where I had set it before.

When it is super cold and the snow is keeping you home from work, it is easy to get the urge to fire up the radios and kill some time rag chewing. But if the antennas are wet, or have been exposed to a cold snap with freezing rain or ice on the trees and lines, you should check your SWR carefully before tuning up.

My ICOM 7000 is set up for quick mobile installation using a 12v battery so I don't have to deal with wiring it into the cars electrical system and a Little Tarheel screwdriver antenna. I can also use it portable and I have it set up in a GO BOX with a matching antenna tuner and a bag of antenna options. I'm hoping to come up with an antenna option for my plane someday, but with a pressurized cabin it is hard to get a connection to an external antenna.

I have always babied my 7000 because of the lack of a built-in tuner. It is a lot of radio in a VERY small package and I would assume it has heat issues if used heavily at max output. My radio works great, and I love the configuration in the Go Box. If you set up at a school or park, you can put the rig box on a park table or use the tailgate of the vehicle and the Tarheel antenna does a great job if you don't want to string up a Pars End Fed antenna.

I rig my antenna feed with a switch option to connect it to an SWR meter with the flick of a switch. This allows me to make sure that before I try to get a tuner match that the antenna has a low SWR in the band I am planning to use.

This is key with Tarheel, tunable screwdriver antenna. It is so much easier to get it set up correctly by switching to a small SWR measurement device like the AA-54 or IP-30z from

Overheating your 7000 is probably much easier if you are driving a high SWR antenna situation. So make sure your antennas are in tune for the band you plan to use.

I may try to post some additional photos of my Icom-7000 set-up, if I can find them on my computer!!!

Stan Brannan, WJ0E

?

One of the things I found out during the recent cold spell was that icing can dramatically alter the resonance and SWR of many types of antenna. I have a multi-band inverted V, an end-fed Pars and a multi-band vertical.

I was trying to demonstrate a small FT-817 QRP rig, and since I did not have any antenna tuner, I used one of my SWR meters, the AA-54 to make sure the SWR would be acceptable. I was shocked by the SWR in all of the Ham bands I was planning to use was very high, and not even tunable my radios with a built in tuner.

I went to broad sweep mode and found the ice or moisture hat moved the SWR point of resonance way out of band. Usually outside the bottom frequencies in the band. So far out my ICOM 7600 tuner could not get an acceptable match.

I left the radios off for a week and after a warm period where the snow and ice were melted, I rechecked all the antennas on all the bands and there was not long-term damage, and they center of the resonant frequencies was exactly where I had set it before.

When it is super cold and the snow is keeping you home from work, it is easy to get the urge to fire up the radios and kill some time rag chewing. But if the antennas are wet, or have been exposed to a cold snap with freezing rain or ice on the trees and lines, you should check your SWR carefully before tuning up.

My ICOM 7000 is set up for quick mobile installation using a 12v battery so I don't have to deal with wiring it into the cars electrical system and a Little Tarheel screwdriver antenna. I can also use it portable and I have it set up in a GO BOX with a matching antenna tuner and a bag of antenna options. I'm hoping to come up with an antenna option for my plane someday, but with a pressurized cabin it is hard to get a connection to an external antenna.

I have always babied my 7000 because of the lack of a built-in tuner. It is a lot of radio in a VERY small package and I would assume it has heat issues if used heavily at max output. My radio works great, and I love the configuration in the Go Box. If you set up at a school or park, you can put the rig box on a park table or use the tailgate of the vehicle and the Tarheel antenna does a great job if you don't want to string up a Pars End Fed antenna.

I rig my antenna feed with a switch option to connect it to an SWR meter with the flick of a switch. This allows me to make sure that before I try to get a tuner match that the antenna has a low SWR in the band I am planning to use.

This is key with Tarheel, tunable screwdriver antenna. It is so much easier to get it set up correctly by switching to a small SWR measurement device like the AA-54 or IP-30z from

Overheating your 7000 is probably much easier if you are driving a high SWR antenna situation. So make sure your antennas are in tune for the band you plan to use.

I may try to post some additional photos of my Icom-7000 set-up, if I can find them on my computer!!!

Stan Brannan, WJ0E

?

Thanks… that makes sense as just the CPU needs “juice” in sleep mode.? It must be another failure mode for the electrolytic caps that like to short in the control head.

I haven’t perused the schematics as well as I should! Hi!

?

Perry – K4PWO

?

?

From: ic7000@... [mailto:ic7000@...] On Behalf Of w3ahl@...
Sent: Monday, January 13, 2014 1:16 PM
To: ic7000@...
Subject: RE: [IC-7000] Radio Restarts on Engine Startup

?

Perry,

?

I believe that all (except one) of the low voltage regulators (including the one for the Display) are after the internal power relay. ?The only low voltage regulator tied to the always hot 14V bus is the 3.3V regulator on the Logic board that allows the CPU to sleep until the power switch interrupt wakes it up.

?

Steve, W3AHL

---In ic7000@..., <k4pwo@...> wrote:

..snip..

?

I often wonder if the somewhat common filter cap failure in the control head (see “Rig won’t turn on” threads) wasn’t due to mobile power system surges.

?

Perry – K4PWO

?

?

?

Perhaps the cheapest and absolute way to deal with all this is to use
one of the 50A or so relays that are available for mobile use. Radio
Shack sold them (may still), might find some cheap at a swap that came
from some commercial mobile installation. Run the relay coil from an
accessory line in the vehicle that's on when running but off when
starting. Shouldn't be hard to find that. This way you won't have to
worry about forgetting to turn the radio off.

Chuck - N8DNX

?

But I think the 7000 is never truly "off".? As long as it's connected to power, the CPU is drawing a few milliamps and waiting for a wake-up signal from the power button. If that's the case, then isn't it still exposed to the same hazards whether it's "on" or "off"?

73, John Bee N1GNV

Quicksilver Radio