AM receiver convert to ATC receiver

From a regen that misbehaves it certainly can.

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Regards, Joerg

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Thanks for the info.

Regards, Bob Monsen

Yes, just about anything and everything that misbehaves can can cause a problem. When I lived in Ketchikan, AK, I received one of those salmon-colored FCC QSL cards from a listening station at Point Reyes, CA due to a misbehaving multiplier in my HT9. Got a 579 on my second harmonic.

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Don't know abou that. When two stations broadcast over each other its generally just distorted garbage. I speak as a pilot, not from theory.

Also speaking as a pilot AND a ham of many years, I believe that a trained ear can ignore the heterodyne whistles of combined signals and hear the underlying messages. Even when one signal largely overcomes another, it is easy to recognize that a second station was there, inviting a follow-up call.

As a pilot too, I know that if people step on each other's communications, it ends up with distortion. Stuck mikes are always a problem. However, the receiver isn't locked onto the stuck mike, and you hear something. ATC can often blast over a stuck mike to get the offender's attention. Also, it is possible for pilots to talk over other pilots at remote fields with the same unicom frequency (very common here in California, despite the attempt by the FAA to spread out the frequency assignments).

Anyway, enough said. I had always been told by instructors/pilots that AM was preferred due to this effect, so I was parroting that (as they probably were), without really examining the claim in detail. However, it does appear to have some merit.

Regards, Bob Monsen

Not to worry. That receiver wouldn't stay on any given frequency long enough to cause problems. Might not even stay in the air band. :-)

Tom

I have tried to read and understand the posts in this thread the best I can. Can someone tell me; Is there a problem for the aircraft industry, or me, if I sit at the end of Regan National airport outside DC and use this,

Thanks.

Wayne

The discussion was about regenerative receivers, which can radiate through their antenna at the tuned frequency. The Ramsey kit is a superhet which might radiate a lot less, and possibly in a different band (e.g. if it uses an IF like 10.7 MHz).

Nowadays, if you were to park anywhere near the runway at a major British airport you'd probably be visited by the police. If you were then found to be operating dodgy home made electronics, any amount of explanation on your part would probably not prevent your arrest. Perhaps it's the same in the US.

Chris

No. It does not use a regeneration type detector.

That one would be worth placing it in a frame :-)

Problem with homebuilt regens is that unless they have a preamp they can easily emit lots of RF power if something goes wrong, straight out the antenna. "Dang, why doesn't it receive anything?" ... "Hey, Joe, uncle Leroy said the ballgame just started." ... "Ok, coming." ... Meantime the regen is forgotten and happily keeps humming until after the overtime. Back when I was a kid people built their own RC electronics because the stuff from companies such as Robbe was financially out of range for most of us. More than once have I seen someone flick that switch on the boat, followed by other boats instantly going out of control.

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As Chris said it's a superhet. Now if the oscillator leaks and the thing runs the usual 10.7MHz IF the oscillator could still land on an active ATC channel. That would mean trouble.

BTW $44.95 is a bit steep. Simple airband radios can be had for less, sans soldering.

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Once upon a time, before Led Zep, I built a super-regenerative receiver that used an acorn valve for the RF gain, a 958 if I remember correctly, a Jackson air-spaced variable capacitor with a knob connected directly to its

1/4" shaft, and a small air-spaced coil wound from chunky silver-plated copper wire. I connected it to the 144 MHz 'ground-plane' aerial I'd installed on a pole at the end of the garden of our family house and found I could tune-in to BBC television sound which, in those days, was AM (possibly around 44 MHz in Band I).

I thought this was a great facility ... until I switched the telly on downstairs and noticed the dreadful interference on the picture of BBC1. Of course, it was my receiver that was causing it. Then I looked outside and realised the distance between my ground-plane and our TV aerial was greater than the distance between it and a load of aerials on other houses. Ooops!

I think I got away with that one, but I learned a bit of a lesson about super-regen (or just regen) receivers that have the aerial connected directly to the detector, not via an RF amp.

Chris

At least you didn't get zinged. When I built my first receiver with controlled feedback (to set the BW) the structure was such that the cap for the feedback had to ride between two points on plate level. Meaning

250VDC or so. No problem I thought since the knob was bakelite and would certainly isolate that. Fired it up, connected earth and antenna, reached for the feedback and *OUCH*. I had forgotten the minor detail that the bakelite knob did not have a recessed set screw.

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respect

Chris

"christofire"

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..... Phil

Hi Wayne

I dont see any problem using that kit to listen to ATC. When I go to the AP on Friday, I will be there with my regen receiver listening to ATC - and I will be 500 meters from the active runway. Cheers

Egad boy, Tenerife was a series of sequential bad decisions and the captain not wanting to listen to his co-pilot. There was never a radio lock out, only a pilot brain lock out. The pilot of one of the aircraft was paranoid of missing his take off because weather was such that he would not be able to leave until the next day so every word he hear his brain misinterpreted. Unfortunately once a VHF aircraft radio press to talk is activated it locks everyone out!!! You can't yell breaker breaker, well ok you can but you won't be heard. This is why I gets real nervous in a high traffic area, I am always afraid that the chatter won't allow me my turn to transmit. .

This all gets a bit muddled when the military are able to use VHF harmonics in the UHF range. I don't know if it is only for distress beacons ( 121.5 Mhz harmonically picked up on 243 Mhz) or if they can do it on other freqs?

Claude

Which probably explains why the new 406 EPIRB transmits to the satellite at

406 Mhz which is ( I believe ) in a protected area of the spectrum. I do agree with you, the power involved is less than 5 watts ( not a researched number) so any hack fooling around with a transmitter in that range could do funny stuff. One new fail-safe feature is active on 406 EPIRBS is that the satellite is listening for an embedded digital signal that identifies the EPIRB. Each device has a unique identifier and the first thing a SAR station does is call the registered owner on the phone. If you own such an EPIRB please ensure that it is properly registered.

While I am here , anyone out there have plans for a functional cell phone jammer that could jamm all 4 protocols to within 50 feet or so? I have seen theoretical papers ( Google) but would like to know if any hobbyist has ever built a successful one?

Claude Montreal