Re: [Elecraft] 12 meter K3 RFI from nearby FM station

On 2/10/2016 1:08 PM, Walter Underwood wrote: > A long time ago, I visited the transmitter room at the top of One > Shell Plaza in Houston. There were nine 100 kW FM transmitters on the > same antenna. The RF plumbing was something to behold, with big stubs > like that all over the place. That's

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

Just a thought: Are all the screws on the K3 case tight? there are a lot of them, and good contact between the case pieces is needed for shielding. Also, I remember being told to remove some insulator tape during assembly. Was this properly done? Grasping at straws - 73 Bill AE6JV

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Alan Sent: Thursday, February 11, 2016 12:04 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] 12 meter K3 RFI from nearby FM station On 02/10/2016 03:57 PM, Jim Brown wrote: > Yes, this hit me between the eyes as well. The K3 has

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

Felton, Delaware www.aa1k.us -Original Message- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Alan Sent: Thursday, February 11, 2016 12:04 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] 12 meter K3 RFI from nearby FM station On 02/10/2016 03:57 PM, Jim Brown

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

Message- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Alan Sent: Thursday, February 11, 2016 12:04 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] 12 meter K3 RFI from nearby FM station On 02/10/2016 03:57 PM, Jim Brown wrote: Yes, this hit me between the eyes

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

ll for the tips. Still absorbing the advice before proceeding. >> >> 73/Jon AA1K >> Felton, Delaware >> www.aa1k.us >> >> -Original Message- >> From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Alan >> Sent: Thursday, Febr

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

I agree. Even better. 73, Ron AC7AC -Original Message- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Bob McGraw K4TAX Sent: Wednesday, February 10, 2016 9:18 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] 12 meter K3 RFI from nearby FM station A

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

On Thu,2/11/2016 10:55 AM, Jon Zaimes wrote: Yes, that is the case. Hearing it on both of my K3 transceivers with only the 12v power cable connected, nothing else (listening on speaker). I'm assuming this means nothing at all plugged into the back of the rig -- no control, no audio, nothing

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

On 02/10/2016 03:57 PM, Jim Brown wrote: Yes, this hit me between the eyes as well. The K3 has Pin One Problems at many (most?) connectors, so RF current flowing on shields of cables plugged into those connectors will couple into the K3. I've been preaching to Wayne about Pin One Problems since

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

I can't imagine 2 KW ERP FM directly causing that issue. In reading the original post, he was getting splatter on 12M which would indicate the antenna was connected. Nothing mentioned about the Preamp being on or off. Normally for 12M it is on, maybe PRE II is on as well. There are

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

t] On Behalf Of Bob >> McGraw K4TAX >> Sent: Wednesday, February 10, 2016 9:18 AM >> To: elecraft@mailman.qth.net >> Subject: Re: [Elecraft] 12 meter K3 RFI from nearby FM station >> >> An electrical 1/4 wavelength of coax as an open stub at the FM frequency, >&

[Elecraft] 12 meter K3 RFI from nearby FM station

I had been noticing some RFI on 12 meters for some time that I initially had thought was power line noise. My use of 12 meters is seldom so it wasn't very high up on the list of things to track. When I was reminded of it while listening for VP8STI recently, I did a little more snooping and

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

Jon, I had a similar problem with a 50 kW AM BC station a few miles away. It turned out to be strong enough to override the bias in the K3's T/R switch. I built a high-pass filter which solved the problem. You would need a low-pass filter in your case. Make sure it can handle 100w, because

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

A single frequency issue like that also can be handled with a simple trap. A small coil with a capacitor across it tuned to the station's frequency at 91.1 MHz in series with the center conductor of your coax. 73, Ron AC7AC -Original Message- Jon, I had a similar problem with a 50 kW

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

Rosenthal 4X6GP/K2VCO Sent: Wednesday, February 10, 2016 10:20 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] 12 meter K3 RFI from nearby FM station Jon, I had a similar problem with a 50 kW AM BC station a few miles away. It turned out to be strong enough to override the bias in the K3's T/R

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

An electrical 1/4 wavelength of coax as an open stub at the FM frequency, connected using a T at the receiver input, will notch the FM TX signal. It won't attenuate other frequencies across the ham bands including 6M. Plus one can transmit with the stub arrangement in place. 73 Bob, K4TAX

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

On 2/10/2016 7:19 AM, Vic Rosenthal 4X6GP/K2VCO wrote: > You would need a low-pass filter in your case. Make sure it can handle > 100w, because you must connect it in the main antenna path -- the RX > in/out path is before the T/R switch. Using a low-pass filter on the output of an HF

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

Subject: Re: [Elecraft] 12 meter K3 RFI from nearby FM station Jon, I had a similar problem with a 50 kW AM BC station a few miles away. It turned out to be strong enough to override the bias in the K3's T/R switch. I built a high-pass filter which solved the problem. You would need a low-pass

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

;; elecraft@mailman.qth.net Sent: Wednesday, February 10, 2016 12:10 PM Subject: Re: [Elecraft] 12 meter K3 RFI from nearby FM station Thanks for the tips. Any filter likely would have to be inserted internally, since I am getting this RFI without any antennas connected to the radios.Unless it is coming i

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

Hi Jon, What you experience is mixing of the FM BC frequency with the 3th, 5th, 7th etc. harmonic(s) of the K3's VCO. If the mix product result is 8,215 Mhz you can hear it. I'm 3 km away from a BC tower hosting 10 station with >20kw each. Used SDR-radio on the K3-IF at 8,215 Mhz to identify

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

A long time ago, I visited the transmitter room at the top of One Shell Plaza in Houston. There were nine 100 kW FM transmitters on the same antenna. The RF plumbing was something to behold, with big stubs like that all over the place. wunder K6WRU Walter Underwood CM87wj

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

I agree. Even better. 73, Ron AC7AC -Original Message- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Bob McGraw K4TAX Sent: Wednesday, February 10, 2016 9:18 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] 12 meter K3 RFI from nearby FM station

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

Graw K4TAX Sent: Wednesday, February 10, 2016 9:18 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] 12 meter K3 RFI from nearby FM station An electrical 1/4 wavelength of coax as an open stub at the FM frequency, connected using a T at the receiver input, will notch the FM TX signal. It won't

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

Since the problem occurs without an antenna connected, it is a version of the "RF in the shack" problem, although the RF field is coming from the nearby FM station rather than the classic situation where the transmitted signal is the source of the RF. Jim makes some very good suggestions for

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

Yes, this hit me between the eyes as well. The K3 has Pin One Problems at many (most?) connectors, so RF current flowing on shields of cables plugged into those connectors will couple into the K3. I've been preaching to Wayne about Pin One Problems since 2004, when we met in Dayton. If the

Re: [Elecraft] 12 meter K3 RFI from nearby FM station

Open antenna connectors are like baby antennas. Terminate the antenna port in question before proceeding. Jim ab3cv On Feb 10, 2016, at 7:25 PM, Don Wilhelm wrote: Since the problem occurs without an antenna connected, it is a version of the "RF in the shack" problem,