NEWBIE to AM needs Advice

[N2LDE]

After many years (I've been a ham since 1970) with SSB, CW, dabbling in contests, getting my first DXCC, ext., I'd love to get into AM, sit back and relax with some REAL QSO's....

I picked up a Heathkit Apache that is in very good condition cosmetically and mechanically, and am about to start checking it over electrically (I have the original manual...the builder took detailed notes in the margins...A good sign!)

I have many questions, and please forgive my AM ignorance, but I though this would be a good place to ask:

1)  I have been reading the board here and it seems as though the audio from the mic (I have several D104's) should be modulated or processed before going into the transmitter. Why is this, and what type of devices do I need? Also, where can I go for additional information?

2) I have an SB-200 linear amp, but obviously that won't work with 100% duty cycle AM. What can I do to get my signal over 100 watts without bringing home a commercial unit the size of a refrigerator?

Thanks in advance for any advice!

Tom
N2LDE

[Steve - WB3HUZ]

Q1. You don't have to use audio processing. Running a D-104 straight into your Apache is fine. I would recommend it for starters. Get the audio sounding good on the Apache first, then add external audio processing, if you so desired.

Audio Mods for the Apache (there are others, ask around)
http://www.amwindow.org/tech/htm/w3sccmods.htm

Primer on audio processing here.
http://amfone.net/ECSound/processing101-1.htm


Q2. Wow. Lots to cover here,  but there are several vintage ham transmitters that will give you around 300 watts out out that aren't anywhere near the size of a refrigerator. Look for Globe King 400 and Globe King 500 and Johnson 500 for starters. Other options are homebrew using tubes or FETs (Class E). Finally, numerous commercially made linears will also give you 300 watts output on AM. Smaller sized units include the Drake L-4B, SB-220 and many of the newer models by Ameritron and the like. You can never go wrong with one of the old Henry pedestal units, like the 2K or 3K. A nice one sold at NEARFest for about $400.

Hope to hear you on the air soon. Welcome.

[Ed-VA3ES]

Never drive a conventional amateur linear with more than about 25W of drive in AM.   With the Apache, try running it in the tune mode to drive a linear.

100W of AM is 400W PEP, way too much for any conventional linear.   You will overdrive the amp and sound terrible.   In any case, driving a linear with 25 W will produce about  250-300 W output from the linear. 

[WBear2GCR]

These mods in general apply to the Apache too...
especially the first two stages: http://www.amwindow.org/tech/htm/dx100.htm

I'd highly recommend removing/bypassing the clipper circuit.

               _-_-bear

[N2LDE]

Bear,

I was looking at the DX-100 audio mods....It makes sense they would apply to the Apache as well.

I need to get the TX-1 up and running well first....I hunting around for a variac to slowly bring it up and check it out....

The tubes seem to be pretty common ones...Are they still available around anywhere?

Tom N2LDE

[w3jn]

Sure they are.  The only expensive ones in the APache are the EL-34s but there are very satisfactory Russian made new ones available.  If you need toobs post an ad here, or www.tubesandmore.com (Antique Electronic Supply).   Not the cheapest around but very satisfactory service.  It's an acutal storefront business, not some dude running a website out of his basement so they stand behind their sales.

[N3DRB The Derb]

do yourself a favor and just replace the 100 uf HV caps. Too critical a part to be left to chance with a "reform" job....also where's the electrolyte layer to reform with? long gone and dried up. All you have left is the foil.

[N2LDE]

Hey Derb!

Thanks for the advice! The Apache reminds me of my first Novice rig I built when I was 16...a DX60-B...Years ago I donated it (along with the matching VFO that I could never quite get aligned properly!) to my local Ham Radio Club (Old Barney ARC) so that other Novices could get on the air.

OT: Good to see another Mac-man...I'm "bi-platform" myself....I have a MAC G5 and a MacBook Pro....Only use my PC's when I really need to...!

[w5omr]

OT: Good to see another Mac-man...I'm "bi-platform" myself....I have a MAC G5 and a MacBook Pro....Only use my PC's when I really need to...!

you've got the perfect call for using a better platform than Winders or Mac...

N2 Linux Desktop Environment

(OS/X I'd consider acceptable )

[N2LDE]

Hey Geoff!

I like your quote about using a scope...For SSB I use a Kenwood 940SAT with the matching Monitor Scope (SM-220)....Do you think that scope would help me out with the Apache?

Tom
N2LDE

[Todd, KA1KAQ]

Tom, I really have to agree with Steve's comment about processing: save it for later - if you do it at all. Some guys use it because they like to, some because they have to, others because they think they're supposed to. A D-104 with a good crystal element will do wonders for you once the transmitter is properly set up. That's all I use and I get great reports.

Get it working well, have someone record you, take a listen and see what you think. You might be very pleasantly surprised. It might not be 'broadcast-quality' audio, but it might sound just like you. Few of us have third-BA voices requiring a lot of bass response.

[w5omr]

I like your quote about using a scope...

Not -my- quote.  That's what Don Chester/K4KYV says

For SSB I use a Kenwood 940SAT with the matching Monitor Scope (SM-220)....Do you think that scope would help me out with the Apache?

Any scope is better than none. 

Personally, I disagree with people who think they need to connect the thing via a padder/attenuator to see what the transmitter is doing.  I'm all for putting a piece of coax on the front of it, and running some sense antenna outside, to sense the RF being produced by the antenna.  At that point, I set the carrier for 2 divisions on the graticule of the scope and then monitor the audio.

Still not sure if 'graticule' is spelled correctly or not.

[Pete, WA2CWA]

Hey Geoff!

I like your quote about using a scope...For SSB I use a Kenwood 940SAT with the matching Monitor Scope (SM-220)....Do you think that scope would help me out with the Apache?

Tom
N2LDE

For monitoring RF output, whether SSB, AM, CW, etc., the SM-220 will work fine. I've used my SM-220 for monitoring the RF output of all my rigs for the last 25 years. I've used the SM-220 even on 6 meters.

[Steve - WB3HUZ]

Good review of the latest OS from Ars Technica.

http://arstechnica.com/reviews/os/mac-os-x-10-5.ars

Hey Derb!

Thanks for the advice! The Apache reminds me of my first Novice rig I built when I was 16...a DX60-B...Years ago I donated it (along with the matching VFO that I could never quite get aligned properly!) to my local Ham Radio Club (Old Barney ARC) so that other Novices could get on the air.

OT: Good to see another Mac-man...I'm "bi-platform" myself....I have a MAC G5 and a MacBook Pro....Only use my PC's when I really need to...!

[N3DRB The Derb]

still running my 2003 dual 1.8 G5. love to get a mac pro but it aint gonna happen. Gonna swing the munky for a while.

[Steve - WB3HUZ]

Got a 2GHz Duo2 machine swinging here.

[N2LDE]

Steve,

Great review of Leopard! I have Tiger running on my MacBook Pro and G5 Dual....There doesn't seem any reason to upgrade....I'll stick with what works!

Tom N2LDE