noise blanker for old recievers

[ab3al]

Just picked up a really nice hq 145x from frank kb3ahe at the post timonium party.  Its a nice clean set complete with frank-en-stein  audio mods and i love it. 
one problem  the  state road recently put in a new traffice signal about 500 ft from the house and like clockwork every 45 seconds i get a 20 over buzz that sounds like a jacobs ladder from 3.5 mhz -4.5 mhz and nowhere else.  I also have a flex 1000 and orion 2 yaesu 920 and kenwood 440.  with each of these receivers some dsp some not all i have to do is switch on the noise blanker and all traces of the noise are gone with no effect on the receive signal or audio.

I have never looked into how these circuits work or how they are put together.  I am looking for an outboard type circuit because i dont want to cut this hammerlund up.

any suggestions.

[k4kyv]

the  state road recently put in a new traffice signal about 500 ft from the house and like clockwork every 45 seconds i get a 20 over buzz that sounds like a jacobs ladder from 3.5 mhz -4.5 mhz and nowhere else.  I also have a flex 1000 and orion 2 yaesu 920 and kenwood 440.  with each of these receivers some dsp some not all i have to do is switch on the noise blanker and all traces of the noise are gone with no effect on the receive signal or audio.

You need something that blanks the signal in the early stages of the receiver, before any significant selectivity.  The ringing effects of tuned circuits and i.f. filters greatly exacerbates the noise situation.

Regardless of your success with the noise blanker, I would also start bitching to the state, regarding the interference, and maybe try to get the FCC involved.  Sometimes all it takes is an official letter from the FCC listing the Part 15 regulations.  That action by a ham in a town near here was all it took to get the manager at the local power company to be cooperative in resolving line noise issues.  That traffic signal should not be radiating electromagnetic pollution to that extent, or actually, any noise at all.  If state officials refuse to cooperate, CC any correspondence to elected officials at the city, county and state level.  Let everyone know that they won't make the problem go away by ignoring it.

This is not the first time I have heard of complaints about rfi from traffic signals, so this looks like another chronic problem that is inevitably going to increase, just like touch lamps, BPL, plasma TV's, etc.

[N2DTS]

I think there are two systems now in use.
The old style has the wire coils in the road, a big metal detector I suspect, and a new system that looks like a camera that picks up heat or uses some other way of telling if a car is there.
On some of the old systems, the light system will hose up a weak or not so weak FM radio, but its odd that it changes with the light colors, you can hear it change between red and green...

Good luck getting them to do anything about it though, those light setups are expensive I think...

Brett

[wb1ead]

Hi Bill..I'm sure that a noise blanker is out there for ur rig..however wondering if ur aware that a least a couple of companies make/sell outboard units to cut down the noise attached in place of a spkr or at the headphone jack..Gap is one and I'm pretty sure MFJ makes one as well..the ads claim wonderful results..and it would be simpler than tearing apart the rig..no Hammerlund is one of the few rigs never owned..surprised they never incorporated one in the circuit...73 de DAVE

[ab3al]

thanks all. 

1: i have considered the shotgun its inside city limits so that may be a problem
2: its a sign that starts to flash warning when the light around a blind turn turns red so there are no sensors. i dont remember them trenching a line between the two so i assume its rf signaled?
3: i am aware of the outboard units by timewave and mother freaking junk and although they would probably work they are about 200 bucks and i was looking for something i could homebrew.

don i fully agree with you about reporting it the only issue is this is maryland.  and as IRB used to say even our flag is standing reminder of our one party monarchy rule.  I will bark and scream at the local municipalities because i can put them in their place quite easily, but when it comes to the state no action against them goes without retaliation.  I need to really have my ducks in a row before i do that.
Not ruling it out but it only affects one old receiver that is going to be a rig for the shop probably paired with a modded dx 40 and a homebrew sweep tube amp for about 100-200 watts carrier.

I have been collecting parts for a k9ay looop which i have wanted for a long time.  Not an expert but the reading i have done about it i looks like up to a 60db null (claimed by some)  with a small receiving loop and a portable set within 100 ft of the signal i can null the sign from an s9 to an s5  and even better in my yard.  the purpose for the loop is really better receive for the dx window and 160 but if it cuts out my noise on 80 even better.

Only problem is Don the sign is s sw of me which means i wont be able to hear you any more.

been nice knowing ya lol 

[KA1ZGC]

2: its a sign that starts to flash warning when the light around a blind turn turns red so there are no sensors. i dont remember them trenching a line between the two so i assume its rf signaled?

Probably, but if it's a pulsating noise, it's coming from the light itself. If it's RF-signalled, the signals are probably "on/flashing", "on/steady", and "off".

Sounds to me like this is a series LED array. Some of them make a gawdawful racket in nearby receivers. We put some screw-in LED bulbs in the kitchen, and they throw horrible trash on the kitchen radio on AM, but I don't hear them in the shack (different building).

They get cheap on a lot of these things and just series up some LEDs to distribute the voltage and bung some resistance in there for current limiting. Real cheap and dirty.

[N3DRB The Derb]

been my experience most NB's simply dont work well enough without also trashing the incoming sig too.

[Pete, WA2CWA]

You could trying utilizing the tube outboard I.F. Noise Silencer (Blanker) that was designed for the HQ-170 and HQ-180 series.

[KM1H]

Do a search on QST, and HRM as they both had NB projects back in the 70's and 80's.

Most, including the Hammarlund, are take offs of the Lamb Noise Silencer of the 30's which first got widespread use in the SX-28.

I have a HQ-180 with the factory installed silencer and it is very effective.

Carl
KM1H

[ab3al]

yep they are led arrays.   the noise is cyclical.  starts every 45 seconds and lasts 15  solid buuuuuuuuuuuuuuuuuuxxxxxxxxxxxxxxxxxxxxxxxzzzzzzzzzzzzzzeeeeeeerrrrrrrrrrr and as it goes off it starts to fizzle out like the buzzer on an old electric dryer.  on ssb it cannot be detected only on am or sync am  Im looking at the circuit posted and have my slide rule out to convert to solid state only because I dont really have the junk box that most of you fellers have.

tnx

[Pete, WA2CWA]

Solid-state Noise Blanker, QST July 1971, page 20.

[KA1ZGC]

Ah... if it's fizzling out, then it's probably not the LEDs causing it. They're either "effing on" or "effing off". That sounds more like ballast radiation.

I had moderate success with noise blankers when the streetlight out front had an oversensitive eye which shut the light off when someone drove through town with their brights on. The eye would momentarily pulse the light off, and the ballast would radiate garbage for 30 seconds until the lamp ignited again.

I lucked out and caught a lineman in a good mood who was going up the pole anyway, he said he knew exactly what was wrong and fixed it. No problem since.

I forget if I had my TR-4 then, or just what I had. I still got a distorted signal with the blanker, like Derb said, but it was intelligible and slightly less harsh.

[k4kyv]

when it comes to the state no action against them goes without retaliation.  I need to really have my ducks in a row before i do that.

What can they do, if your action is legal and proper (like NOT using the sawed-off 12 gauge)?  I would think it would be the local yokels that would be more likely to engage in "retaliation".  I would keep on pissing and moaning till they fixed the thing just to shut me up.

File a complaint with the appropriate state authorities, with as much documentation as you can, and then document in detail their response and any corrective action or lack thereof.  When you have enough evidence on hand to convince the FCC that you have made a good faith effort to go through the proper chain of command to correct the problem, send a letter to the Enforcement Division, along with photocopies of all your documentation.  A letter or phone call from the FCC may be all it takes to prod them into action. 

That's how the fellow here handled it with the local power company.  I recall the FCC's action on the issue made national news in QST, This week in amateur radio, Newsline, CQ and Worldradio a year or two ago.  When I had my recent line noise problem, I talked to the manager after they said they "couldn't find anything".  He seemed to bend over backwards to assure me that the problem would be fixed "promptly".  That was Xmas Eve, so I figured that meant within the next couple of weeks.  The noise problem went away about 4 hours later, and hasn't returned.

Before, when I would have a problem, the linemen would do their best to fix it if I woul lead them by the hand to where the power leak was, but the central office was very uncooperative when I tried to go through them.  I had to use the night time emergency number and talk directly to the repair crew to get anything done.  This last time, I went through the central office, and they put me through to the head honcho right away.

I wouldn't be intimidated by them.  This isn't Iran or Pakistan (yet).

[Steve - WB3HUZ]

If reducing the noise from a particular local source is your goal, the K9AY is probably not your best bet. I'd go with a small loop, preferably one based on the design shown below. You can put a null on the local noise, yet still receive higher angle incoming signals (like Don-K4KYV  ) from all directions. You loose almost nothing but the noise.

I have been collecting parts for a k9ay looop which i have wanted for a long time.  Not an expert but the reading i have done about it i looks like up to a 60db null (claimed by some)  with a small receiving loop and a portable set within 100 ft of the signal i can null the sign from an s9 to an s5  and even better in my yard.  the purpose for the loop is really better receive for the dx window and 160 but if it cuts out my noise on 80 even better.

Only problem is Don the sign is s sw of me which means i wont be able to hear you any more.

been nice knowing ya lol