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Author Topic: 2Meter AM  (Read 39842 times)
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Old_Bill
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« on: February 03, 2010, 12:00:05 PM »

All,

First time on the board and I hope I am in the right place.  I am in the process of constructing a 2 meter AM transceiver, that first appeared in a 1959 issue of Radio-TV Experimenter.  After 51 years of looking at it I decided now is the time to build.  However, in looking at the band plans I see nothing specifically designated for standard AM.  So the question is, on what frequency if any would this device be allowed to operate, so I know it the effort is worth continuing.  Power output is about 3-5 watts max.

Thanks so much and I look forward to any reply.

Tom
KK6XK, Northern CA
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Steve - WB3HUZ
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« Reply #1 on: February 03, 2010, 12:11:25 PM »

You would be allowed (per FCC) to use the rig anywhere between 144.1-148.0 MHz. However, you should consult the band plan, and determine if there is any AM activty or nets in your locality.

Many AM Nets listed at the link below.

http://www.amwindow.org/stuff.htm
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« Reply #2 on: February 03, 2010, 12:28:14 PM »

Not sure what is going on in six-land, but there is virtually no 2 M AM activity here in the Midwest.  Since the advent of 2 M. FM, most of the 2 M fone activity is on FM.  There is also quite a bit of activity on SSB for weak signal work.  6 M, on the other hand, does still have some AM activity albeit somewhat scarce.  AMers are usually found around 50.4 MHz.

One of the most common rigs that was very popular on 2 M AM back in the 60's was the Heathkit Two'er along with the Sixer on 6M.  Those little rigs were called the "Benton Harbor Lunchboxes" and worked quite well in spite of their low power and rather broad super-regen receivers.  You would be wise to check around your area and see what kind of activity, if any, there might be on 2M AM.  Also, as previously suggested, check out the ARRL band plan for 2M.  You are to be commended anyway for embarking on a home brew project.  Good luck.

73,  Jack, W9GT

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n7ioh
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« Reply #3 on: February 03, 2010, 01:07:50 PM »

Hi Tom, the frequencies I have written down for 2 Meter AM are, 144.400, 144.425, and 144.450MHz.  I don't remember where I found them but I wrote them down just for reference.  I have thought about trying 2 Meter AM but never have.

Al, n7ioh
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« Reply #4 on: February 03, 2010, 01:17:03 PM »

Tom,

I'm in the Santa Cruz mountains, and have 2meter AM mobile capability, although I'm not sure if I mountaintopped I'd be able to hear you...  50 watts PEP / about 10 AM carrier.

You get it built, I'd be willing to climb a 2500+ foot mountain and give it a shot Smiley


--Shane
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Old_Bill
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« Reply #5 on: February 03, 2010, 03:18:28 PM »

All,

Thanks to all of you for your prompt response and encouragement.  I believe the original 1959 circuit came from C.F. Rockey, W9SCH.  I tried corresponding with him at his QTH in Wisconsin but no response as yet.

I'll investigate those suggested frequencies and try to find a good one.  Looks like if I stay out of everyone else's way it will be OK.

Tom
KK6XK 
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« Reply #6 on: February 03, 2010, 03:29:40 PM »

The AM calling frequencies vary a bit around the country but most are in the 144.4 to 144.5 range. Ive heard of some at 144.3 but that in the beacon band.

I have 100W carrier from a Clegg Zeus and will have a quad of 17B2's up in warm weather but dont think I can span the continent even to Shane Roll Eyes  I also have an old 500W carrier Class C amp and could quickly hook up the PP 8000 modulator.

How about building something for 6M? Thats an easy double hop on Eskip, The Zeus has done that many times there. The calling freq is 50.4

Carl
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Pete, WA2CWA
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« Reply #7 on: February 03, 2010, 03:42:00 PM »

I agree with Carl. Build something AM for 6 meters. For most of 2 meters, the "FM's" and the "diddle-diddles" are the most active. If you build this thing for 2 meters, most likely you'll wind up mostly talking to yourself. The last time I made two 2 meter AM contacts in one day (and they were by prior arrangement) was back in the middle 90's.
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« Reply #8 on: February 03, 2010, 08:54:36 PM »

Id love to see some real AM activity on 2M with some power. Simple to build these days compared to the 60's...lots of choice tubes and parts.  It needs to start in populated areas such as the Boston to DC corridor and coverage should be better than 75 for many stations using a single or stacked yagis.

Carl
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« Reply #9 on: February 03, 2010, 09:07:57 PM »

I have a 2M AM/CW HB, rack mounted. Uses a 829B in the final modded by a pair of 807's. I can't swap lanes right now 'cause I have other things in process, but I'd like to get it going. The builder did a great job: i'ts from the late 50's.

Phil
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« Reply #10 on: February 03, 2010, 09:34:42 PM »

You would be allowed (per FCC) to use the rig anywhere between 144.1-148.0 MHz. However, you should consult the band plan, and determine if there is any AM activty or nets in your locality.

Many AM Nets listed at the link below.

http://www.amwindow.org/stuff.htm

How about 144.107 - 147.973 Grin

If that New York 144.280 net is listed it may be time to remove the listing. Those guys have not been on there for 15 years.
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Old_Bill
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« Reply #11 on: February 15, 2010, 04:26:59 PM »

All,

For now I am going with 145.692- AM simplex- it's in the middle of what they call Misc. and Experimental of the ARRL band plan.  Every other frequency seemed to be taken up by pretty specialized assignments.

Anyone see anything wrong with that pick- am I missing anything

Again, the set is going to run about 3-5 watts max.  The receiver is done- when we have the transmitter and PS complete I plan to put it all into an old suitcase and haul it up to the top of Mt. Diablo (about 4,000 MSL in the East Bay- Northern Calif) and see if I can manage a contact with someone.   Since there is a repeater up there running less than a watt that gives full quieting down here it should do something. 
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« Reply #12 on: February 15, 2010, 05:09:07 PM »

I'd pick something around 144.2, the SSB calling freq..   you'll stand a beter chance of contacting someone than up yahr.

klc
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« Reply #13 on: February 15, 2010, 05:24:00 PM »

At least down around 144.2 to 144.275, the SSB stations can at least detect that you're there and zero beat. If your receiver has a BFO, you can still copy someone calling you. Horizontal antenna polarization also helps to get the signal out. Above 145 MHz, almost everyone is channelized, antenna vertically polarized, and for the most part, sitting in front of an FM rig.
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Old_Bill
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« Reply #14 on: February 15, 2010, 08:40:58 PM »

Gents:

Thanks for the comments and excellent points.  I can pre arrange the initial test.  If it all works out OK, I'll try the lower frequency.
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« Reply #15 on: February 16, 2010, 06:55:16 AM »

Here in Manchester NH they use 144.450 and there are an assortment of rigs starting to get back on the air. I am in the process of resurrecting and old SCR-522 Transmitter which has been souped up to 15 Watts out and a HB converter on an old ARB receiver.

Mike WU2D
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« Reply #16 on: February 16, 2010, 09:37:41 AM »

Clegg !

http://oldradioclassified.com/item.htm?nbr=577

Good case for getting all those shelf queens on the air.
Gorgeous just doesn't get it if you can't use it.
And there is activity if all you metro owners would get them off the shelves.
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« Reply #17 on: February 16, 2010, 10:14:33 AM »

I use a Clegg Zeus and Interceptor B on 6 and 2M but havent had a 2M QSO in ages, I think there is still a 6AM Sunday group in the Boston area but I could care less at that hour Grin

The new 2M 4 bay array should be up by summer. Not needed for Mike, I can see Manchester from the tower. Cheesy

Carl
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Todd, KA1KAQ
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« Reply #18 on: February 16, 2010, 10:41:43 AM »

There was a VHF group around Schenectady NY that was active a couple years back. I could sometimes hear bits and pieces over in VT. Also the group in the Boston metro area, though I was never able to hear them up my way. For a while the 6m band had a lot of AM activity a couple years back when HF band conditions were so crappy at night. I recall K1JJ making multiple references to the gay 6 meter band, PT Cruisers and so on.  Grin

The Clegg gear is sweet to use when you can find someone to talk with. I've used the Venus a number of times on SSB (no AM activity in VT then) and the Interceptor receiver has gotten a lot of use with the Allbander converter for HF listening. Even the 2m CB crowd has thinned quite a bit in recent years. Have yet to use the Zeus on the air, though it is ready to go. Would probably help to have an aerial up for those bands.

Carl, I'm curious what you've found for absolute high power out with yours. Clegg ads in '61 went from claiming 175 to 185 watts of 'talk power' claiming it sounded stronger than many kilowatts. Should be easy enough to drop a 4CX250 in place of the 150 as well for loafing along at full output?

Did manage to snag some spare 7558s at Shelby.

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« Reply #19 on: February 16, 2010, 02:10:39 PM »

I worked the Albany/Schenectady crowd at 9PM on 6M most evenings when there was no DX worth chasing on the low bands.  When they went off Id swing the 8 el long boom down south a bit and work the guys on LI, NJ, and down to Phillie.

On 2M I could do the same with the stacked 4218XL's but there were very few with anything over 10W and tiny antennas on their roof. Id call CQ and could hear weak carriers with no audio and the only time we could work was during a good tropo lift.

The Zeus will run 125W carrier on 6 and 105-110 on 2M with good tubes. Ive a 250B in there now but there is no difference between a 150A with the low plate and screen voltages available. Im also using Svetlana 572B's in the modulator for the same reason....more plate dissipation overhead for old buzzards.

Im sure with SS in the PS I could pick up a little but 125 to maybe 140-150W aint worth the effort.

Ive done nothing to the audio. Close in contacts say its a little restricted which is what it was designed for. I only run the clipper at part way for long haul and reports are of excellent punch.  One of these days I may change the values and open the response a bit but its not on the priority list.  I remember many Zeus stations in the 60's and the audio was commanding to say the least, and not harsh.

The Interceptor B with the nuvistor front end is hot. The receiver backround noise is so low you would think its dead but then signals just explode in. Clegg took their engineering seriously.

Both units are so stable I can work 6M AM to SSB for long ragchews which I find absolutely amazing. Often they dont even realize Im on AM.

Carl

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IZ0MFI
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« Reply #20 on: February 17, 2010, 05:39:52 AM »

All,

For now I am going with 145.692- AM simplex- it's in the middle of what they call Misc. and Experimental of the ARRL band plan.  Every other frequency seemed to be taken up by pretty specialized assignments.

Anyone see anything wrong with that pick- am I missing anything

Again, the set is going to run about 3-5 watts max.  The receiver is done- when we have the transmitter and PS complete I plan to put it all into an old suitcase and haul it up to the top of Mt. Diablo (about 4,000 MSL in the East Bay- Northern Calif) and see if I can manage a contact with someone.   Since there is a repeater up there running less than a watt that gives full quieting down here it should do something. 
Great Tom, be carefull to shielding of quenching noise through 12AT7 preamp  Grin
A prayer: do not replace the tuning eye with a moving coil meter.
In Rome for few sporadics BA net we use 144.250 Mhz near .300 ssb calling frequency, is always a variation of the amplitude modulation or not?  Roll Eyes
Have a god job
'73 marco

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Todd, KA1KAQ
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« Reply #21 on: February 17, 2010, 09:46:20 AM »

In Rome for few sporadics BA net we use 144.250 Mhz near .300 ssb calling frequency, is always a variation of the amplitude modulation or not?  Roll Eyes

You are absolutely correct, Marco. SSB is really AM with one sideband and the carrier suppressed. All of those SSB stations are really just transmitting modified AM.  Grin

Carl, after the 80 and 160 aerials are back up in the air (80 this weekend of all goes well), I'm going to get something set up for 6. Would be cool to work you and Pete, Clegg-to-Clegg. WA2PJP also runs this set up from Long Island.



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Pete, WA2CWA
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« Reply #22 on: February 17, 2010, 10:32:27 AM »

Maybe I'll go Li'l Lulu receiver/transmitter big time this summer on 6.
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« Reply #23 on: February 17, 2010, 11:17:29 PM »

I was going to do a converter but I actually forgot I had an old R-19 / R508/ARC on the shelf. This is a cute late model 119- 148 MHz command style receiver with 4 mini tubes and 4 loktals and a 12A6 output stage.

It was given to me on a rainy day at Deerfield a while ago. Anyway it is wired for 14VDC and takes 250V. Anyway, I fired it up and it receives 2M AM just fine. I can imagine the NF is a bit high with two PENTODE 9003 RF stages!!! Looks like I have a station of sorts just about ready - a SCR-522 TX and the R508 RX.

Now for an antenna.

Mike WU2D


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* R508.jpg (34.29 KB, 500x375 - viewed 529 times.)
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« Reply #24 on: March 07, 2010, 08:36:08 PM »

I finally got a small beam up and worked two 2M AM Stations tonight on 144.450 MHz. The old SCR-522 does over 18 Watts souped up. It uses combination driver and final plate modulation. The Rx is a bit deaf. The R-508 uses a three pentode front end with those half pint sized peanut tubes - 9003 RF, 9003 2nd RF, 9003 Mixer, 9002 OSC, and then three stages of IF at 15 MHz. I can only imagine the noise figure!

Mike WU2D


* R508_2M_Junk_RX.jpg (182.19 KB, 1500x1125 - viewed 546 times.)

* SCR522_Beast.jpg (162.08 KB, 1500x1125 - viewed 596 times.)
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