The AM Forum

Hey guys, I've been wanting to get on AM for many years but never really did anything about it.  However, I am think I am finally ready to start putting together a station.  I want to keep the station as compact as possible but still have decent receive and transmit audio.  I've read Johnny's RX guide many times over the years but most of the rigs, with the exception of the Drake series, seemed huge compared to what I was wanting.  However, I recently discovered Slab Bacon's RX guide and intrigued by his comments on the Hammarlund HQ-110 (not discussed in Johnny's guide).

I've found an OM selling a clean and working HQ-110 along with a Knight T-150 transmitter.  Would this make a decent AM station for a newbie?  Ultimately, I'd like to build a Class-E transmitter.

Thanks

- JT

Sure it would!  A great beginner station, but don't expect a rock crushing signal or broadcast quality audio.

I'm of the opinion that you should buy the best receiver you possibly can from the gitgo to avoid frustration, but OTOH there's nothing wrong with starting small either.

A compact station is one goal, to be sure, but I'll betchya sooner or later you're gonna be jonesing for an old broadcast xmitter  ;D

I agree, I'm just not sure what to buy for a receiver.. even after reading Johnny's and Slab Bacon's guides.  Although, the NC-183 that W4WSZ is selling here might be a good choice.

- JT

An HQ-110 isnt a bad receiver for a starter, they usually go fairly cheap and perform very well for a lower end receiver. the Q-multiplier gives good adjustable selectivity, and they have enough IF bandwidth to make pretty good audio with Larry's feedback mod.

An NC-183 can make very good audio, but is a little broad for crowded prime time band conditions. However they can kick butt and take names if you add an outboard Q-multiplier like one of the old Heathkit QF-1s (I think thats the model #)

However I would reconsider the T-150 for a transmitter. IIRC they are screen modded in the phone mode and only put out something like 25 or 30w in AM. A Johnson Viking 2 or Greafkit DX-100 or Apache would be a lot better choice, as they are relatively cheap and plentiful. And also put out 100w. T-150s are kind of wimpy.

FWIW, I will be adding another 5 or 6 receivers to the "Road Test" article sometime this winter, as soon as I get some time to type it up.

                                                     The Slab Bacon

Thanks for the reply Slab Bacon.  I just made an offer on W4WSZ's NC-183 with speaker.  I'll pass on the Knight T-150 and look into a better TX for now until I build my own.

- JT

Welcome aboard JT !

The 150 wouldn't be bad - around 100w out into a good working antenna at a decent height will get you coast-to-coast.

Geoff,
        IIRC the T-150 will only do 100w on CW, but does something like 25 or 30w in Am. I think they were scream modulated in the phone mode. (but I have been wrong in the past) You might want to check on that.
   
                                           The Slab Bacon

Well, I downloaded the manual from BAMA and it says 150W input power and doesn't really say there is any power difference between AM or CW.  It is, however, screen modulated.

- JT

Best receiver (price/performance) for AM use is an old Hammarlund SuperPro - SP200, SP400, or the military BC-779/BC-1004.  The separate power supply is a pain, but beautiful audio, stout construction, and some really great features not found in other receivers.

Hi JT, 

Welcome to AMFone. :)

73,
Ellen - AF9J

Thanks for the welcomes everyone.

It looks like I am going with an NC-183.. I just made the commitment to buy W4WSZ's rig.  I think it will work for my needs, not the best but the price seems decent.

Now I need to go research some transmitters.

- JT

GO find a carcass of a transmitter with the caps and coil(s) in it, still...

put some of your own tubes in it.  The grid circuit you'll have to build will depend on what you put in the final.  Triodes are easier to tune.  A Pair of 811's would yield around 180w, if you don't push 'em hard.  Another pair in the modulator would be a great rig!

Modulators are -much- easier to build than finals.

Bob got enough of my money this week already, thanks.  ;D   I've never spent $3K on a car and I'll never spend $3K on a rig or "turn-key" system.  No way, but I will spend way more than that cumulatively on various stuff in the shack.   ;D

- JT

Welcome to AM.
Just because you are planning on running AM does not mean you have to use a receiver that was designed before Christ was born.
check out http://www.amqrp.org/kits/softrock40/version5.html for information about the softrock converters.
they are neat and $$cheap little SDR receivers.
if you have a decent computer you will be amazed at how nice they perform.
I have the Flex here and I don't think i could ever go back to a tube receiver or even a late model ricebox.
again, welcome to AM and hope to hear you on soon.

Blaine
N1GTU

You won't meet a bigger computer geek than I, but I really like turning big knobs.  I wonder if that's why I always seem to date girls with big.. oh nevermind, I'll just get in trouble.   ;D

- JT

What's the fun in that  ??? ???

Mind you, my opinions are based on the opinions of using other people's receivers.

I think if you can find one you can afford, you could not go wrong with a National NC-183D, though I believe an NC-183 is almost as good, especially if you like the light through the dials.  I almost got one.

But in the same price range it seems a Hammarlund HQ-129x/HQ-140/HQ-150/HQ-160 would server you well as well.

I'm looking for an early Hallicrafters SX-28, but I do not find them affordable.

I also believe, as well many seem to, that a Hammarlund SP-10/200/400 is a fabulous choice for an AM receiver.  While they are a little more expensive, they are actually an under appreciated value.

Welcome to AM.  I only recently have been able to get on the air after a lot of reading and questions myself.

I've always been under the impression that the NC-183D is crap compared to the NC-183. I've got both a 183 and a 173, but I've honestly never fired either one up. I'm quite fond of my HQ-129X, but I would love to have an HQ-170A.

Don't automatically rule out a screen-modulated transmitter, either. With a small amount of tweaking, some of them can be made to sound pretty good. Nobody's going to shun you for running something other than high-level plate modulation. It's not that everything else sounds like unmitigated garbage, it's just that plate modulation is the most effective in terms of fidelity.

Along those lines, if you want to start small and simple, a Drake TR-4 is a good place to start. They're screen-modulated, and they don't need a whole lot of work to sound good on AM. Chris W2JBL uses a TR-3, IIRC, and sounds good on it. 3 6JB6s are probably good for 15-20W of AM comfortably.

Some things to consider, anyway. Welcome to AM!

--Thom
Killer Agony One Zipper Got Caught

Thanks for the comments Thom.

I've purchased an NC-183 already for a RX, hopefully it will arrive here sometime late next week. 

- JT

I prefer recievers with skirts!

 ;D

Ya, that's the ticket! A dame with a sharp skirt!!

The older boxes are very nice things, but the selectivity is not what I prefer to listen to. My TS-440 with the +/-4.5kHz. Ceramic Filter mod runs rings around my R-388, unless the band is clean and clear... I can listen to the guys out west of here (8,9,0 land) on 3880 while there is a QSO on 3885 here in the NE! Can't do that with the R-388. I doubt that the older venerable receivers have better selectivity than the R-388, which has a Crystal filter, albiet not a good one...

Otoh, if you have a rig with a 455kHz. IF than you can "drop in" a Mechanical or Creamic (read: cheap but effective) filter as a mod. I would.  ;D

           _-_-bear

I'm now officially obsessed.  I'm driving down to Massachusetts tomorrow to pick up some gear.  I'll be coming back with the following:

• Heathkit KL-1 Chippewa with KS-1 HV supply
• Some type of mod iron with a stripped Warrior chassis for building a modulator in
• 6' Rack Cabinet that the Chippewa, KS-1, and Warrior is mounted in
• Knight T-150
• Knight T-60
• Heathkit DX-60 with matching VFO

I'll have pictures tomorrow night.

- JT

Oooooohhh!  That Chippewa is a cool amp.  Runs a  pair of 4-400's, and is grid driven.    Sort of a poor-man's Desk Kilowatt. 

Now I need a matching Apache for it.  Send me one of yours.  ;D

- JT

An Apache would over drive it, even in the "tune" mode.   Besides, the frieght costs of shipping would exceed the value of the unit.  And, I'd insist on being paid in Canadian dollars,  not your  dollarettes!  :P :D

That's odd, the Chippewa manual states that the amplifier was designed for use with the Apache. 

- JT

Unless I'm mistaken, I thought that the Chippewa was grid driven?   Even if not, and it's grounded-grid, you still can't drive it with 100W of AM.  That's 400W PEP, and too much for any conventional amp.   25W is sufficient, and the Apache will do that in the "tune" Mode.

HA! And when was the last time you could say that, Ed?? There was a good reason for calling those coins 'Loonies' and 'Toonies'.   ;)


Probably with output padded down somewhat? Johnson actually made a couple of attenuators specifically to allow rigs like the Valiant and others to interface with the Viking Kilowatt.

The Chippewa has specific control connections on the back for the Apache.  The manual makes it very clear that the Chippewa is designed with the Apache in mind. 

The Chippewa features two grid configurations.  From the manual:

"When the "R" position of the GRID BAND switch is selected, the entire tuned circuit is bypassed and the second or resistive grid current is employed.  The input excitation is delivered to a 170-ohm 80W, non-inductive load resistor.  The voltage developed across this resistive load provides the required driving voltage for Class AB1 operation.  This grid circuit configuration can be used only for Class AB1 linear operation but has the advantage of being capable of using higher power exciters as drivers without the necessity of power reducing networks.  No neutralization or grid tuning is required on any band in Class AB1 linear operation because of the very heavy grid loading provided by the swamping resistor."

- JT

Ahha!! this is the same scenario as the Junkston Invader 2000 and Thunderjolt! Blow the power into a built in dummy load and use the obtained voltage across said dummy load to tickle some AB1 grids.

It does a good job of swamping down the grids and keeping the amp stable.  One of these days when I dont have anything better to do, I'm gonna experiment with some mods for my Invader 2000 to convert it to grounded grid / cathode driven and see if I can get a little more snot out of it. As designed, with the I-2000 you cant adjust the loading of the 6146s when you switch into the high power
mode and fire off the PL-175s.
                                                      The Slab Bacon

Built-in attenuator. Clever. IIRC, the Chippy is somewhat scarce compared to the Warrior amp? Would've been the crowning piece for that excellent Heath package (Apache, Mohawk, Marauder) offered on ebay last week.

Looking forward to hearing it on the air.

From what I've gathered, there were only about 100 made.  I can't find any pictures online of any actually units.  Just plain photos from old Heathkit catalogs.

I'm leaving here in a few minutes to go get it.

- JT

Got back home a little while ago and just now finished unloading the Chippewa, big iron, and other assorted goodies I came home with.  Cabinet and transformer for the high voltage supply are sitting on my porch, I need to go to UHaul tomorrow and rent a beefier dolly.  Mine didn't cut it.  The transformer weighs more than the cabinet does!   ;D  It isn't an HS-1 matching supply for the Chippy, I was under the impression it was, this thing is a much bigger homebrew supply!

Pics coming up in a little bit.

- JT

Hi JT,

Nice find with the Chippewa!  I picked up one last year, also with a very large HB supply.  A couple of Chippewa cautions:

1.  The large tapped resistor on the topside of the chassis is in a position where it is easily damaged, the ham I got mine from had already replaced it after he damaged the original while removing the case.  You can turn the resistor slightly to move the tap side so it is not as likely to suffer damage.

2.  The plate current meter is in the HV lead to the plates and has full plate voltage/current across it.  Keep your fingers away from the meter while operating.  Once in awhile everybody makes a bad design decision and this is definitely one of Heath's bad decisions.

3.  If your power supply was built with 866A or 872 (or any other MV rectifier) be sure and run them filament only for at least 10 minutes to make sure any little mercury blobs in the wrong place get vaporized.  You only need to do this long warm up once (or every time the power supply is moved in such a way that the tubes are tipped, inverted, or greatly shaken).

4.  Your blower will benefit from having a bit of oil added to the oil ports.  Ditto the fan in the Apache.

I like the Chippewa a lot.  Mine is paired with an Apache/Mohawk/SB-10.  I also have a Johnson Pacemaker/T-Bolt setup and the design is pretty similar and the performance seems to be about the same but the KL-1 is certainly much more scarce.

Rodger WQ9E

N1ESE, JT.

I fully agree with Slab Bacon about the Q Multiplier......

If you would like to have one to go with the receiver I shipped you.

I have one FREE for the postage..

Let me know.

73, Bob,W4WSZ

N1ESE,

The Q Multiplier will be mailed tomorrow....enjoy

73,
Bob,W4WSZ

As usual, Slab is right.  Definitely hard to tune in AM stations on 75 when crowded.. especially at night.  During the day, the daytime crowd sounds real nice.. even the 3910 guys :D
 
- JT

JT,
    IIRC you were also getting a Q-multiplier with that rx also??
If you did, get it working and install it. It will make a TREMENDOUS improvement to it's selectivity!! Mine with an outboard Q-mult was pretty good to use when things got crowded. You could dial up the best compromise between fidelity and selectivity.

                                                      the Slab Bacon

Yup, but it's not here yet. 

- JT

Thatz right!! And dont you forgit it!! ;D ;D