• Get involved.
    We want your input!
    Apply for Membership and join the conversations about everything related to broadcasting.

    After we receive your registration, a moderator will review it. After your registration is approved, you will be permitted to post.
    If you use a disposable or false email address, your registration will be rejected.

    After your membership is approved, please take a minute to tell us a little bit about yourself.
    https://www.radiodiscussions.com/forums/introduce-yourself.1088/

    Thanks in advance and have fun!
    RadioDiscussions Administrators

AM receiver with S-meter recommendation?

J

JasonW

Guest
Hello All,

I'm looking for an AM receiver that has an S-meter, so that I can tune a nearby Part 15 AM transmitter's 3 meter antenna.

Can anyone here recommend one? It needn't be anything fancy.

Many thanks in advance to anyone who can help. -- JasonW
 
I used an ElCheepo Radio Shack V.S.W.R. meter in the field strength mode. I wrapped some wire around a broom handle and put one end in the place where you would normally insert the field strength antenna on the meter. (The longer wire, the more signal you will collect) I place the broom and the meter close enough to where I could read the meter on a plastic lawn chair. Worked for me..<P ID="signature">______________
"What is this R.F. and How Does It Do That?.."</P>
 
> I'm looking for an AM receiver that has an S-meter, so that
> I can tune a nearby Part 15 AM transmitter's 3 meter
> antenna.
________________

With any poor AM receiver having a ferrite loopstick antenna and a headphone output jack, maybe you could connect an a-c voltmeter to the rx audio output, orient the rx antenna so that the Part 15 tx antenna is in/near its null, and get a useful indication for tuning? The meter would read the noise level on the rx signal, so tuning the tx antenna in the right direction will reduce the noise voltage on the meter, as long as the rx signal stays down near its sensitivity threshold (below much AGC leveling). The tx antenna would have to be in a rather clear area so that its signal wasn't re-radiated by nearby wires, etc, and make the receiver hard to null.

I have no idea if this is practical, but it would be fairly easy for someone to try, and report back.
//
 
> Hello All,
>
> I'm looking for an AM receiver that has an S-meter, so that
> I can tune a nearby Part 15 AM transmitter's 3 meter
> antenna.
>
> Can anyone here recommend one? It needn't be anything
> fancy.
>
> Many thanks in advance to anyone who can help. -- JasonW
>
Hi Jason,

I know of no low $ receivers with an S meter. Even if one is available, if it is close to the antenna, it will probably saturate and not give a clear peak signal strength indication. I have a Yaesu FRG-100B and it is not usable for antenna tuning for this reason.

I think the best approach is to use a field strength meter. These are very easy to build. Just a couple of diodes, caps., inductor, resistor, and you can use your DVM as the readout. Search "field strength meter" and you will get several circuits.

I tune my transmitters using an oscilloscope connected to a test antenna. This gives a very sharp peak indication. If you are lacking a scope a simple field strength meter is a good choice. For tuning you do not have to be concerned about the calibration since all the readings are relative.

Neil
 
> Hello All,
>
> I'm looking for an AM receiver that has an S-meter, so that
> I can tune a nearby Part 15 AM transmitter's 3 meter
> antenna.
>
> Can anyone here recommend one? It needn't be anything
> fancy.
>
> Many thanks in advance to anyone who can help. -- JasonW
>
Find an old Radio Shack DX-160 Communications Receiver, has an S Meter, covers 150 kHz to 30 mHz. Can also be used to check harmonics...
 
I thank you all very much for your replies. I have an MFJ-802 Field Strength Meter, but the needle doesn't budge even when set for maximum sensitivity and held 1" away from the radiating antenna. I once had an MFJ-801 which worked, although the needle didn't move much at all even when very close to the transmitting antenna.

I do have a Radio Shack CB/ham SWR meter that displays relative power. If it has a Field Strength mode, I'll try it with a short wire sensor antenna. -- JasonW
 
> I thank you all very much for your replies. I have an
> MFJ-802 Field Strength Meter, but the needle doesn't budge
> even when set for maximum sensitivity and held 1" away from
> the radiating antenna. I once had an MFJ-801 which worked,
> although the needle didn't move much at all even when very
> close to the transmitting antenna.
>
> I do have a Radio Shack CB/ham SWR meter that displays
> relative power. If it has a Field Strength mode, I'll try
> it with a short wire sensor antenna. -- JasonW
>


JasonW,

I although I have an MJF Deluxe Versa Tuner II SWR, I use my Grundig S350 radio with it's digital S-meter to tune the AM and FM transmitter from various distances and it does work very well... the added benefit of digital display plus manual tuning allows for very fine tuning and adjustment for getting the most out of the 'field' strength of the transmitters... the simple hand held field strength meters are worthless, I have the MJF-801 (simple diode/meter) type and it cannot read any signal from 2-3 feet away from the antenna... impossible to tune an antenna with this little amount of power using the field strength meters....

Radiopilot
 
Thank you, Radiopilot. I just snagged a new Grundig S350 off eBay. I like Grundig's radios to begin with, and the S350 has other features I like (including full Short Wave band coverage) in addition to the digital S-meter. -- JasonW

> I although I have an MJF Deluxe Versa Tuner II SWR, I use my
> Grundig S350 radio with it's digital S-meter to tune the AM
> and FM transmitter from various distances and it does work
> very well... the added benefit of digital display plus
> manual tuning allows for very fine tuning and adjustment for
> getting the most out of the 'field' strength of the
> transmitters... the simple hand held field strength meters
> are worthless, I have the MJF-801 (simple diode/meter) type
> and it cannot read any signal from 2-3 feet away from the
> antenna... impossible to tune an antenna with this little
> amount of power using the field strength meters....
>
> Radiopilot
>
 
> Thank you, Radiopilot. I just snagged a new Grundig S350
> off eBay. I like Grundig's radios to begin with, and the
> S350 has other features I like (including full Short Wave
> band coverage) in addition to the digital S-meter. --
> JasonW


You will love this radio! I've had mine for two years and this baby goes with me everywhere... infact I have a permanent 150' long wire antenna for the AM shortwave in my yard and it picks up some pretty distant stations, the FM also has antenna inputs and it greatly helps reception too... the only problem I had with the unit is that the headphone output is mono only for both AM and FM... strange because it has left & right stereo output???? The sound is rich in AM and you'll never know that you're listening to AM...

When you recieve yours, give us your input about the radio and how great or badly you percieve it... Grundig has done a good job on the S350 radio.

Cheers,

Radiopilot
 
> I thank you all very much for your replies. I have an
> MFJ-802 Field Strength Meter, but the needle doesn't budge
> even when set for maximum sensitivity and held 1" away from
> the radiating antenna. I once had an MFJ-801 which worked,
> although the needle didn't move much at all even when very
> close to the transmitting antenna.
>
> I do have a Radio Shack CB/ham SWR meter that displays
> relative power. If it has a Field Strength mode, I'll try
> it with a short wire sensor antenna. -- JasonW

Jason, I too had an MFJ-802, and it did nothing. I tried it with various LPAM transmitters. I tried it with 2 meter. I tried it with CB, nothing. I even brought it to one of the 1000 watt AMs that I work with, and standing right next to the tower with the meter about 18" away from the tower...nothing.

I sent the meter back to them. One of the techs told me that they tested it and it was working fine. Then he asked if i wanted it back, wanted another one or just wanted a refund. I opted for the refund.
 
> > I thank you all very much for your replies. I have an
> > MFJ-802 Field Strength Meter, but the needle doesn't budge
>
> > even when set for maximum sensitivity and held 1" away
> from
> > the radiating antenna. I once had an MFJ-801 which
> worked,
> > although the needle didn't move much at all even when very
>
> > close to the transmitting antenna.
> >
> > I do have a Radio Shack CB/ham SWR meter that displays
> > relative power. If it has a Field Strength mode, I'll try
>
> > it with a short wire sensor antenna. -- JasonW
>
> Jason, I too had an MFJ-802, and it did nothing. I tried it
> with various LPAM transmitters. I tried it with 2 meter. I
> tried it with CB, nothing. I even brought it to one of the
> 1000 watt AMs that I work with, and standing right next to
> the tower with the meter about 18" away from the
> tower...nothing.
>
> I sent the meter back to them. One of the techs told me
> that they tested it and it was working fine. Then he asked
> if i wanted it back, wanted another one or just wanted a
> refund. I opted for the refund.
>
###############################

I'm curious, guys..
Does that meter have a place in the top or side somewhere to put an external antenna on to it? My elcheepo rad shack unit has one and it worked great! (or good enough to find a peak)<P ID="signature">______________
"What is this R.F. and How Does It Do That?.."</P>
 
> Hello All,
>
> I'm looking for an AM receiver that has an S-meter, so that
> I can tune a nearby Part 15 AM transmitter's 3 meter
> antenna.
>
> Can anyone here recommend one? It needn't be anything
> fancy.
>
> Many thanks in advance to anyone who can help. -- JasonW
>
Jason,

Congrats on your acquisition. Let us know how it works out for tuning your system.

Just an additional comment about field strength meters. They will work with part 15 AM but you have to use germanium diodes and a digital voltmeter. The ones mentioned in this thread, I believe, use D'Arsonval meters (analog with a pointer). D'Arsonvals just require too much current for these low powers. So anyone thinking about building a field strength meter, be assured they work if built as I described.

Neil
 
> I'm curious, guys..
> Does that meter have a place in the top or side somewhere to
> put an external antenna on to it? My elcheepo rad shack unit
> has one and it worked great! (or good enough to find a peak)

The MFJ-802 has a 1/4" jack for a remote sensor antenna. It also has a 1 meter long adjustable dipole (two telescoping whip antennas) that are screwed onto studs on either side of the case. -- JasonW
 
> The MFJ-802 has a 1/4" jack for a remote sensor antenna. It
> also has a 1 meter long adjustable dipole (two telescoping
> whip antennas) that are screwed onto studs on either side of
> the case. -- JasonW


WOW! I don't understand why you don't get some kind of reading. On my elcheepo, there's a metal piece with a hole in it that a short antenna fits into. I lost that antenna long ago but I used a piece of wire.. around 6-8', twisted it so to fit into that metal thingie, strung it in the area of my antenna about 3-6' away, set the meter on "fwd" and turned the control on the meter all the way to the right,(max sens.) I could get almost half of the meter in signal strength. (at this settting when connected to just a cb, it would slam the meter big time when keyed)

http://img246.imageshack.us/img246/2797/20030102antpic00028rg.jpg

http://img248.imageshack.us/img248/8563/20030102antpic00039yp.jpg

You can see the broom with the stick taped to the end and the wire hanging down to the plastic chair where the meter is setting..
As you can see, I still had some headroom on the control..<P ID="signature">______________
"What is this R.F. and How Does It Do That?.."</P><P ID="edit"><FONT class="small">Edited by Offgridkindaguy on 01/12/06 12:21 AM.</FONT></P>
 
The meter on the MFJ-802 doesn't move even when the dipole is *touching* the transmitting antenna! The needle isn't stuck--it sways freely when I tilt the unit.

Nice Part 15 AM set-up in the pictures! Is that a chicken wire ground screen? I'll bet it's a lot easier to put down than an equivalent number of radials. My Radio Shack CB/ham SWR meter (Cat. No. 21-534) measures SWR and transmitter power calibrated in watts, so I don't know if it would double as a field strength meter. -- Jason

> WOW! I don't understand why you don't get some kind of
> reading. On my elcheepo, there's a metal piece with a hole
> in it that a short antenna fits into. I lost that antenna
> long ago but I used a piece of wire.. around 6-8', twisted
> it so to fit into that metal thingie, strung it in the area
> of my antenna about 3-6' away, set the meter on "fwd" and
> turned the control on the meter all the way to the
> right,(max sens.) I could get almost half of the meter in
> signal strength. (at this settting when connected to just a
> cb, it would slam the meter big time when keyed)
>
http:> //img246.imageshack.us/img246/2797/20030102antpic00028rg.jpg
>
>
http:> //img248.imageshack.us/img248/8563/20030102antpic00039yp.jpg
>
>
> You can see the broom with the stick taped to the end and
> the wire hanging down to the plastic chair where the meter
> is setting..
> As you can see, I still had some headroom on the control..
>
 
> I used a piece of wire.. around 6-8', twisted
> it so to fit into that metal thingie, strung it in the area
> of my antenna about 3-6' away,
____________

If it was parallel to, and 3-6 feet away from your Part 15 AM radiator then very likely your field meter antenna was affecting the performance of your Part 15 AM antenna. Then the correct tuning of your Part 15 antenna would change when the field meter antenna was removed.

The field meter needs to have enough sensitivity to give a usable reading further away, say 30 feet or more. For Part 15 field levels this usually needs some kind of amplifying circuits to drive the meter.

Communications receivers with "S" meters have more than enough sensitivity, in fact probably too much for the most useful display. If used, its antenna should be shortened or even removed, and/or the receiver should be located far enough away to keep its field strength indication in the lowest part of its total display range (less than S 9). Higher readings are compressed, and don't show the effects of tuning the Part 15 antenna as well as lower readings do.
//
 
There are a bunch of older Micronta and such FS meters up on ebay for less than $10. Go to ebay and search on "field strength meter".

> Hello All,
>
> I'm looking for an AM receiver that has an S-meter, so that
> I can tune a nearby Part 15 AM transmitter's 3 meter
> antenna.
>
> Can anyone here recommend one? It needn't be anything
> fancy.
>
> Many thanks in advance to anyone who can help. -- JasonW
>
<P ID="signature">______________
Phil B
</P>
 
Status
This thread has been closed due to inactivity. You can create a new thread to discuss this topic.


Back
Top Bottom