1.73mhz

[KMA367]

The old police MW band was 1600 to just above 2500 kHz (some locations licensed as high as 3200 kHz, but I don’t find records of operation that high). This was initially one way, from station to police car, to respond the mobile unit would have to stop at a call box. Later some systems used MF station-to-car and VHF car-to-station. As late as 1964 LAPD was still dispatching on 1700 kHz (according to Electric Radio #169, June 2003).

Specifically, LAPD dispatched on 1730 kcs from about 1940 (when they were shifted from their original 1931-issued 1712 kcs) until August, 1965, when all dispatching was finally consolidated on VHF-high frequencies for both uplink and downlink.

A 1730 transmitter remained in place, though with with unknown usage, at their original (and still in use as of 2016) TX station in Elysian Park. They kept the 1730 kcs frequency on their primary "KMA367" license until they requested that it and two VHF-high uplink frequencies be deleted as part of their FCC license modification #12965-PP-38 which took effect June 26, 1978.
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[N9JIG]

Several of the older Illinois State Police posts had 1700 band transmitters in them in the past and had brass placards on them with their call signs. These signs remained on some of the posts and may still even be there today. I recall seeing the signs at the old District 3 building at Harlem & Irving in Chicago, District 13's old building in DuQuoin and at least one other that I cannot recall right now.

I have pictures of some of these buried in my archives someplace but I am sure it will be months before I can find them again.

 

[Dude111]

You need to stop using 98se and use Linux. Get rid of that old IE for the love of God!

How do you even visit a SSL site that uses SNI?!

I dunno if I can or not,could you provide a site that does and Ill try?

But the point im making is WHY USE HTTPS WHEN HTTP WORK FINE??


See buddy.. Look here

[color=1]http://d39pklu5rpk118.cloudfront.net/forums/images/misc/navbits_start.gif[/color]

Now look here

[color=1]https://d39pklu5rpk118.cloudfront.net/forums/images/misc/navbits_start.gif[/color]

See they both work but 1 of them can cause potential connection problems........

 

[jwt873]

I got a 1.7Mhz cordless phone the other day .

Back in the early 1980's I got my first general coverage ham radio (an IC-751A). It was also my first radio with modes other than just CW and SSB

While listening around I came across a few cordless phones being used in the 1700 to 1800 khz range. They were using FM.

I don't know how the antenna system works on the early 1700 khz phones, but one night one of the callers gave his address to the person he was calling. It was a full city block away. I recall being impressed with the range

 

[N9JIG]

I too had one of these first generation cordless phones, I was a pre-driving-age teenager when we got it. We used to ride our bikes all around the neighborhood and see how far we could go with it, calling our friends while on their porch and generally having a great time with these new toys.

One day I was riding around with it and ventured a couple miles away and for grins and giggles tried it there. I was really surprised to get a dial tone. I must have been smarter than the average kid and tried calling my own number, expecting a busy signal. When my home phone rang and my sister answered I figured out that I must have accessed someone else's cordless system of the same type as mine. The game we played then was to see where else we could go with these. We found dozens of these all over town that summer and had a blast. Kind of a 1970's version of wardriving (warbiking?)

I suppose we could have done some nasty things like calling long-distance but we never thought of it. In those days a call outside 50 miles was considered a long-distance toll call so we really could have racked up some peoples bills but we were either too naive or afraid of getting caught to do that.

 

[Dude111]

I don't know how the antenna system works on the early 1700 khz phones, but one night one of the callers gave his address to the person he was calling. It was a full city block away. I recall being impressed with the range

Yes they really do well!!!!! (I think they use the electric network as an antenna,im not sure...... The base AND HANDSET do have antennas themselves so i dont know really)

 

[N9JIG]

As I understood it at the time, the handset and the base units used the whip antenna for the 49MHz. side.

For the 1700 KHz. side the handset had a ferrite bar with looped wire antenna just like AM transistor radios of the day had.

The base unit had a coil wrapped around the line cord inside the unit to use the house wiring for a radiating element for the 1700 KHz. side.

We had some old tube-based household intercoms that also used the house wiring for the radiating element, I suspect these also used some sort of coil coupling to accomplish that.

 

[Dude111]

Its quite fascinating!!!!

I have a 46Mhz phone also.... The range on that is quite good also!! (46Mhz phones were the last GOOD ones made)

 

[Dude111]

I have always been curious why it says these phones are "Am modulation"

www.wikipedia.org/wiki/Cordless_telephone


THEY ARE ON FM!!!!!!!! -- @ LEAST THE ZETA ONE I HAVE IS!!


I turned my scanner to the freq and had it ring. IT IS ON THE FM SIDE!!

 

[N9JIG]

The 1.7 MHz. side of these phones were almost always AM, the VHF side was almost always FM. Every one of the ones I have used were this way.

There may be exceptions but I have never seen one myself.

Also, while Wikipedia is an excellent source in many instances, it is not authoritative since anyone can edit it at will.

 

[Dude111]

Well you know what am AM signal sounds like if you listen to it on FM right? (And what an FM one does listening on AM) well this sounds like it should ON FM!!!

I went to 1730Khz and I went to FM,the ring sound sounded perfect. (Like I was listening in the right mode)


Maybe this is a slightly newer Zeta model I dunno.......

 

[ratboy]

They did have amazing range, especially some of the non-FCC approved ones. A neighbor 4 blocks away from me had one that would totally cover up my next door neighbor's phone which was usually on the same frequency. One time, I heard someone several towns over order pizza, and couldn't believe how far away it was, over 12 miles, and it was crystal clear. I admit I called the number they gave to see if it was really where they were calling from. It was.

 

[Dude111]

Well I tested this zeta phone I have.... IT MUST BE A PIECE OF JUNK.... It doesnt go as far as my AT&T 4200 cordless does!! (46Mhz)


Ah well............

 

[K2RNI]

Wirelessly posted (Opera/9.80 (BREW; Opera Mini/6.0.3/27.2354; U; en) Presto/2.8.119 320X240 LG VN530)

IIRC, the 1.73MHz cordless phones used that band for base-to-handset, and 49MHz for handset-to-base.

The really old originals were all around the 1.7 range on both.

 

[Dude111]

Ah that must be why,mine is a newer one with transmit on 49!