[AMRadio] AM from a HW-101

Thu Dec 11 22:22:22 EST 2003

What is the bandwidth in the AM position?
I think it was something like 8khz at the 6 db points, 
and 25Khz at the 60 db points.
I had two of them, and they were so wide as to be unusable
under normal conditions where you have AM signals every 5 kc.

Worlds best receiver?
What makes it so great?
The large selectivity choices?
The hi power hi fi audio output?
The passband tuning?

I notice that the 75s-3 added the provision for an AM filter,
so Collins saw the need for one.
The 75s-3 sells for a lot of money, but the 75s-1 can be got
quite reasonable, partly because of the improvements in the 75s-3
along with the provision for more filters.

I would just do what Collins did, and add a good filter for
AM reception.

Brett
N2DTS

> -----Original Message-----
> From: amradio-admin at mailman.qth.net
> [mailto:amradio-admin at mailman.qth.net]On Behalf Of Jim Isbell
> Sent: Thursday, December 11, 2003 2:23 PM
> To: amradio at mailman.qth.net
> Subject: Re: [AMRadio] AM from a HW-101
> 
> 
> I find the 75S-1 to be an excelent receiver on AM/CW/SSB without any 
> modification.  I wouldnt do anything to mine for fear of 
> screwing up one 
> of the best designed receivers in the world.
> 
> I might try to get AM out of the 32S-1 however.  There is a 
> mod for that 
> on the 32S-3 and I am sure it could be adapted to the 32S-1
> 
> Brett Gazdzinski wrote:
> 
> >The resale value aside, I think the 32s-1 would do better,
> >I think it actually uses a 455khz IF, you might be able to 
> do something
> >with that.
> >The 75s-1 type receiver could likely make a real nice AM 
> receiver, top
> >quality,
> >with the addition of a good kiwa filter in line with the back to back
> >IF transformers used on AM.
> >Standard setup is way to wide, but a 5.5khz filter between 
> the transformers
> >(tacked on) would do wonders.
> >it would only be in circuit when the AM mode is selected.
> >It could be tacked on without any modifications, and you
> >could power it from rectified filament voltage, or even batteries.
> >
> >Some slight circuit changes and an external audio amp, and 
> you have a great
> >overall receiver for cw, ssb and AM.
> >
> >Any rig that runs 100 watts pep output on ssb is only going 
> to be good for
> >10 to 20 watts of AM, but driving an amp would be useful indeed.
> >
> >Its easy to unbalance the modulator using a small pot
> >(for carrier level control), getting both sidebands I would have to
> >look at the design....
> >
> >It would be quite neat to have a nice sounding well working
> >Collins S line on AM and ssb.
> >
> >Perhaps trade the hw101 for a less nice 32s-1 and try 
> experimenting on that.
> >
> >What about screen modulation of the amp?
> >That would likely get you a few hundred watts of AM out, 
> with very little
> >audio power.
> >Modulation can be very nice if kept on the low side, don't 
> expect 150%
> >positive, but I have heard some really nice DX60b transmitters
> >running screen modulation...very good fidelity overall.
> >
> >If space is at a premium, take over the basement, put a 
> couple of small
> >rack cabinets on the desk, one big 6 foot rack in the shack, a
> >shelf above the S line, or get something like a Gonset G76.
> >The G76 runs about 70 watts of plate modulated AM output in a unit
> >smaller than a 75s-1, and its a trans-receiver.
> >The receiver uses a 262Khz IF, which works well, its quite 
> attractive,
> >stable, accurate, and fun to operate.
> >It does 80 through 6 meters, AM and cw, and can copy ssb.
> >
> >Its got problems, audio quality is not top notch, but they are
> >extremely robust radios.
> >I operate mine at higher voltages then you are supposed to, its been
> >abused at pre hamfest drunken campouts, complete with rain, excessive
> >beer, wires thrown up in trees, and it just always works.
> >
> >I used to have two of them, but sold one for some reason.
> >
> >They seem quite rare these days, I don't know why.
> >Its smaller than a ranger, puts out more power, and has a 
> good receiver
> >built in.
> >
> >I made some changes to mine, removing the receiver audio 
> output section
> >that used the transmitter audio driver tube and transformer, 
> and installed
> >a small IC chip that does 6 watts of hi fi audio.
> >Lots of feedback around the modulator cleaned things up nicely,
> >low frequencies do not pass the driver and mod transformer well,
> >the driver transformer could likely be improved, but there is no room
> >for a bigger mod transformer if you want it inside the nice slide
> >off case.
> >I might look into something like a pair of AB1 tubes as modulators
> >instead of the triode connected 6DQ6 tubes.
> >Crazy setup, triode connected, the suppressor grid gets the audio
> >signal input I think!
> >
> >They are easy and fun to work on, two screws and the case slides off.
> >It weighs about 10 pounds, easy to toss about.
> >
> >Did I mention its FUN to operate, and quite attractive with 
> its backlit
> >tuning dial and meter?
> >
> >Takes a D104, an antenna, and away you go.
> >Anything will work as an antenna, even a wet noodle, nothing
> >seems to bother the rig.
> >Its got a low power mode (10 watts) and a high power mode,
> >depending on how much you load it, 70 to 90 watts out.
> >
> >If I could only have one very small radio, the G76 would be it.
> >
> >Brett
> >N2DTS
> >
> >
> >  
> >
> >>-----Original Message-----
> >>From: amradio-admin at mailman.qth.net
> >>[mailto:amradio-admin at mailman.qth.net]On Behalf Of Jim Isbell
> >>Sent: Thursday, December 11, 2003 10:02 AM
> >>To: amradio at mailman.qth.net
> >>Subject: Re: [AMRadio] AM from a HW-101
> >>
> >>
> >>Brett Gazdzinski wrote:
> >>
> >>    
> >>
> >>>Why would you want to do that?
> >>>
> >>>
> >>>      
> >>>
> >>Well, to answer your question,....because there is not more
> >>room on my
> >>desk for ANOTHER piece of equipment.  I already have a 32S-1, 75S-1,
> >>Station Console, and Power supply for the full S-Line, a
> >>4-1000A Linear
> >>amp, a computer and now the HW-101, .  There is no more room.
> >> If I want
> >>AM it has to be from the 32S-1 (wonder why the 75S-1 has AM
> >>but the TX
> >>doesn't??) or from the HW-101.  But then I could plate modulate the
> >>4-1000A with a pair of 833As in push pull...but I think that would
> >>really take up some room, and the winters are not cold enough
> >>for that
> >>down here on the Third Coast.
> >>
> >>I have a Viking Ranger, but no room on the desk for it.
> >>
> >>
> >>
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> >>
> >
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> >  
> >
> 
> 
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