The AM Forum

I have been listening to quite a bit of AM phone at nights, and have found something quite intriguing with it vs. SSB.   The conversations seems more relaxed, friendly, and yes....seems like often there's a greater mix of younger folks in there compared to SSB.  My observation has been that it's a nice mix of oldtimers with tons of experience and a younger crowd too.  Everyone seems laid back and polite.  Haven't heard any cursing or drunks yet.  I like what I've heard.

Anyway, I'm wanting to eventually try it out.  My current choices are adding an AM filter to my TR-4C (not sure I'm up to that task), or get an entry-level boatanchor transmitter meant for AM in the first place.   

I'd like to hear some AM "newbie" transmitter recommendations.  I've read up on a bunch - DX-60, the various Johnson's, etc.   Any advice on either option is much appreciated!

Also, if anyone has a recording of the receive of a TR-4 w/AM filter modification, I'd love to hear it.  The stock TR-4c sounds terrible on receive, not sure on transmit!

Welcome to the AMfone board, Bill.

This may be a good way to get the TR-4C sounding good on transmit AM:

http://www.amwindow.org/tech/htm/t4.htm

Good luck with the project and have fun on AM.

Tom, K1JJ

Thanks Tom, I appreciate the link.   I believe I would also need to do the Inrad AM filter mod due to to the TR-4's unusable AM receive audio.  What is the advantage of having screen modulated carrier vs. controlled carrier? 

73,  Bill

regular screen modulation would produce a normal AM signal with full carrier all the time. Controlled carrier modulation is form of screen modulation, but the difference is the RF final is putting out a lower level of carrier when no modulation is being applied, then as the final is being modulated, the carrier increases with the averaage level of modulation.

Don't have be tube gear that is up to Bill some run transcivers like TS-940s sound pretty good TS-440s Can Sound good I done mine for am not done with it yet but works pretty good way it is but when your doing 75 meter am need a bit more power then 25 watts amp can help that or 40 meter people have ran a DX-60 at 7 watts can do an ok job there amp helps but all what you like and what you want to do! me myself I like tube but i am doing a TS-440 just to play with all in fun some run what they have some sound ok some don't but don't let that stop ya don't need a boat anchor get on am! I'm only 36 yrs old

look at Gerry's mobile   http://www.youtube.com/watch?v=CyGMO89RD9o

                                                                                                                Carl KB3RDT

Not to detract from the thread, but can you occasionally put some punctuation in your dissertations so we can follow along with what you are trying to say.
 

aaaahhhhhhhh what part of the band did you say that you do not hear cursing and drunks???
Just kidding,,,,slightly. If you don't mind bodily sounds, like belching, you will enjoy the many QSO's and the technical side of Ham radio.
Welcome to the pleasant sound of AM
I'm KC4MOP and hang out on 40M or mainly 160M.

How's your wallet? Starting out might be best with a 100 watt TX and Receivers come in many flavors. My choice was from my military background and I have an R390A. But starting out for you would be a choice you can make from others advice here on AMFONE.
Do you have any equipment now?? Look in our FOR SALE section and you can see what's available there. Usually at Hamfester prices not eBay prices.
Fred

Hi Bill,

The main disadvantage of having a controlled carrier vs: a fixed carrier is when there is an interfering hetrodyne on AM, the controlled carrier signal will cause this beat note to go up and down in intensity with modulation. This can be annoying as well as making it more difficult to copy. I also question the undesirable AGC effect this carrier bounce may have on the receiving end.

The advantage of controlled carrier is because the carrier drops down during modulation pauses, there is less amplifer heat (less electricity used) than fixed carrier methods.

Most folks prefer the fixed carrier method. This can be achieved with most any AM lashup, from a ricebox driving a linear, class E or class C tube rigs, etc.  The  Drake T-4 AM mod gives you a fixed carrier and will work as well as any of these modes for fidelity. You will need a linear amplifier to increase your power level.  

General AM power in/out efficiency will vary greatly, depending upon the overall design and lashup.


On the Inrad filter - first experiment with a small value capacitor across the AM filter socket. Sometimes a 30 pf, etc., cap can work very well. It's a trade-off between bandwidth, signal level, etc.   Of course the Inrad filter is better, but at $120/ each, you might be satisfied with the cap for high fidelity local work. For rough conditions, I always switch to a narrower ricebox receiver.

T

When I had my Drake TR-6, seems to me I remember the manual saying to remove a 10K resistor between input and output terminals before installing the AM filter.

Hi Tom, my problem is that my unit is the TR-4c transceiver and does not have a slot for an additional filter.  The modification requires wiring a relay and such along with a custom mounting bracket for the AM filter to be squeezed in the chassis.   The instructions seem to call for using the NB switch to engage the AM filter.  Most TR-4c's don't have a noise blanker and the switch is connected to nothing.  However, I do have the NB installed.   

I've been looking at Jeff Covelli's modification page for this:  http://www.wb4hfn.com/DRAKE/DrakeArticles/TR4-AM-MOD2/TR4-6-AM.htm .   

I would not know where to put the capacitor to experiment as you've suggested.

Thanks,

Bill

Hi Bill,

After looking at the mod page, maybe the AM filter would be your best bet.  

Bear in mind that this 6kc filter will give you ~3kc audio to listen to. Some AMers like a little wider like 4-5kc or so.

If you were to experiment with a capacitor and/or resistive network in place of the filter, it would go in the same place as the AM filter mod.

Except for doing all the Sherwood mods on my previous Drakes twins, I haven't had specific experience with the Drake receivers for AM, so you might ask around some more so you don't reinvent the wheel.  I have used the capacitor trick on many receivers in the past until I finally settled on the wide SP-600 13kc filter position. (6.5 kc audio) Now I use an HPSDR receiver that gives a wide range of brick wall effects.

T

Yes, I'm going to noodle on it a bit.  I realized that the link I provided above is just one of the ones I've been studying.   WB0IQK has a filter mod on Jeff's site specifically for the TR-4C and really is the one I was referencing when talking about the relay, etc.   

http://www.wb4hfn.com/DRAKE/DrakeArticles/TechTips/TR4C-AM-Filter.htm

By the way, on a semi-unrelated topic, I can't say enough about Jeff's service.  I sent him my rig about a year ago and it came back essentially brand new.  I admit I'm a little apprehensive about fiddling with things, but I can probably get over that.

-Bill

If you are looking for 'near' broadcast quality AND a modern radio combined, consider a Flex SDR.  I run my Flex 3000 at 10 Watts of carrier into an AL811H amplifier to get 100 Watts of carrier peaking to 400 Watts on voice peaks.  It compares very well with any high level modulation boat anchor.

That is a very interesting idea.  I actually have looked at the Softrock Ensemble II as a possibility for a receiver...as the AM receive audio in my TR-4c, as it exists today, is absolutely unusable.   I have no idea how the transmit audio is....

Ive learned to just skip over that sort of post, its too aggravating to read much less comment.

Carl

A barefoot DX-60 will have a hard time being heard on the crowded bands but it is an excellent rig to drive a linear amp that has a marginal PS such as the Heath SB line. Only about 15-20W is needed for a SB-200 and a little more for a SB-220.

There are several articles on improving the DX-60 audio.

Otherwise a 100W plate modulated rig can often hold its own in a roundtable unless it attracts a slopbucket bozo cuz its weak. Thats when the guys with big amps and antennas crank up the juice and take the frequency back ::)

Carl

I'm not familiar with the Softrock you refer to, but there are several Flex users on both 75 and 40 AM in Texas, OK, and LA that I've heard. Usually in afternoon (1-4 PM) I will be on 7160 if you want to arrange a sched.  That way you can hear a Flex first hand.  We can work cross-mode if that is more convenient.

The Flex has great receive audio as well as transmit audio if you set it up with the 4 kHz BPF.

73 - Gary - W5GW

DX-60 -- about a 100 bucks.

Viking II/ Apache/  DX-100  -- couple hundred bucks

Flex....  uhm... more than I can afford at the moment!

Since he's in the Northeast, almost any late afternoon or evening on 75 M within easy listening distance, you will find someone running a Flex 3000 or 5000 on AM.

I'm actually in the Dallas, TX area......

Sorry, I was looking at the old K3WEC owner's location.

Read my bottom page line....

                     V

73DG

OK!!  Sorry I sometime's just type what i want to say not thinking of things running together! What i was saying it Don't take much to get on AM mode.

Hey, I appreciate your advice as well as everyone's.  I'm not asking for a Master's Thesis here...just suggestions as I try to get on the AM mode!  Thanks!