The AM Forum

OK...We have enjoyed a nice discussion about first rigs.  I'm wondering what sort of interesting and usual rigs some of you might have on AM.  I'm sure there are many one-of-a-kind rigs and probably some really neat home brew rigs out there in radio land.

My contribution is my prized Federal 167B Marine Transmitter.  It is a commercial marine rig off of a ship...built by Federal Telephone and Radio Corp. in 1943.  Runs a pair of 813s in the final with a 76 VFO osc and a whole string of 6L6 multiplier stages.  It was originally just on CW-MCW in marine service and was powered by a motor-generator set.  I built up a modulator for it using a pr of 811As with an all-triode line-up in the speech amplifier.  Uses 12Ax7---6C4---pr 6B4s driving the 811As.  This transmitter originally covered 2-24 MHz, but works fine on 160, 75, and 40.  Runs close to legal limit out and, I'm told,  sounds pretty good for such an old relic.  I have only seen one other Federal 167B and that was at Fair Radio....perhaps 30 years ago.  I was, however, recently contacted by another ham who has one....so I guess there at least two in existence that are on AM.

The 167B is similar electrically to the more common 167BY which was physically much larger and was used on the Liberty Ships in WWII along with the famous Scott SLR-F or H receivers.  The 167BYs were sold as surplus after the war and an ad appeared in CQ magazine for them in 1948.

All-in-all the old Federal is a really neat old rig.  Built like a battleship (no pun intended) and works really well on AM.  I picked mine up at the Wabash, IN hamfest in 1991 and after about a year of work to get it on the air, I have enjoyed it ever since.  I even wrote an article about it that appeared in March 1995 Electric Radio.

Well....that's my story....what other neat rigs are out there????


73,  Jack, W9GT

mine is my big transmitter: A 4-1000a modulated with a pair of 2E26's!

I bet that makes you scratch your head a little ;D ;D. Screen grid and control grid biass modulated in faze. Using an ARC-5 mod transfoma. It loafs along at "legal limit" and is just about bulletproof!!
                                              The Slab Bacon

At First I thought mine would be a toss up, either the HB 1940 transmitter running a
6V6, 807 and a pair of Taylor T-40's in PP or the Early Globe CHamp, the
proto type built for about 3 months in 1947...it ran a single TZ40 in the output
but now I think the 1936 All Star TX , she was make in Chicago...6 ft black wrinkle, 838 in PP modulated by a pair of 838's...
400 watts of pre war glory!
73 steve
8tow

Pearce-Simpson Islander 90, a marine band HF rig bought at a hamfest for $25 after the opening of the new FM VHF Marine.

90 watts out of a 12DQ6, I re-crystalled and re-tuned it to 75m using a base loaded 6M whip antenna on the bumper of a 1971 Capri.

Worked Pete WA1SOV from Connecticut to Virginia as my first contact.

What was the efficiency in the 4x1?

The 1kw dissapation of the 4x1 is what makes it work. It runs somewhere around 33-35%
at resting carrier, the efficiency then swings with the audio peaks. At 400w resting carrier it is just starting to show some color on the plate, the plate actually cools off with the modulation. Been running 6 years now, it thinks its a timex!!

How can I resist Jack?!

RF Deck:
20 Power mosfet (FQA11N90's) in 4 modules of five in push-pull driven by a Pulse Width Modulator delivering
46 volts at 26 amps of modulated D.C.
Power supply is a 5 KVA isolation transformer backwards connected and full-wave bridged delivering 130volts at as many amps as needed, primary running on 220v A.C.
Modulator throttled back to deliver about 120 percent modulation envelope.
Efficiency is about 95%
Power output.....well lets just say legal limit!  ;)


Definitely a one of a kind...all boards are dead-bug construction on copper-clad for reduced ground and inductive looping.

Rcvrs: An old NC-300 and a highly modified FT-990 with all audio stages taylored by Chuck K1KW...runs about 11 Khz bandwidth for Hi-Fi reception.


Brent W1IA

I think my weirdest rig was after I cornered the 50C5 market at HossTraders in '95.

The creation was SIX 50C5's in parallel plate modulated by quad 50C5's in push-pull parallel. With 700V on the plates I was able to get out about 60w carrier in PissBeat service.  I did go thru a fair amount of tubes after this abuse. I'm sure some guys here still remember it on the air.

Just to continue the trend and make it a happy couple, I built up a super-het RX using all 50C5's. It actually worked FB on AM.  All of these rigs were minature and built on those small radio shack mini boxes with an outboard power supply. Totally modular. (totally narly)

The Tron visited and saw the whole station in operation. You can't make up stuff that's this stupid, so it's gots to be true!

T

Depends on what you mean by "odd" :-)

The oddest rig I ever built (that worked) was a pair of 6146Bs in the RF final configured as two independent PHASE MODULATED RF amplifiers combined to produce AM.  The output of the two 6146 tubes was combined with two PI networks and a single loading capacitor.  Set the phase angle at 135 degrees between the two amplifier stages for the carrier.  90 degree difference was 100% positive mod, 180 degree difference was 100% negative mod (no output).

A few folks on the board probably remember the transmitter from back in 1973.  The audio was quite nice!

I'm going to try that method again some day in my copious free time :-)

Regards,

Steve

A few years ago I built a home brew station . The transmitter is a 6L6 Xtal Osc. modulated with an old Heath lunch box. The receiver is a one tube regen. The third piece is a two tube audio amplifier / power supply for the receiver.
http://home-and-garden.webshots.com/photo/1165066775034691539fLffEx

Hmmmm..................  Amplifuzz!!    (or amplifaze for those who have never heard of it)

I actually pondered building one of those a few years back.

AM by Hewlett Packard...HP3325A function generator to an intermediate power amplifier driving an SB-220. Line level audio into op amp / complementary symmetry pair to modulate the generator AM input.  Makes essentially perfect sine, triangle and squarewaves from 1 Hz up through, well... Doubt this is a new idea though...

Rediscovered AM about 6 months back after an being absent from AM since high school (a long time ago).
This is my first post to the AM Forum so hello to all.  Will be at the traders of Hoss this weekend so looking forward to meeting AM'ers there. Oh yeah...also do boat anchor stuff as well...

73
Jay, W1VD

 


 

I have a set of Morrow twins that I hope to have on the air by the end of the year. Should be fun to operate these radios from my home. They were designed as moble radios but Morrow also had a 120 volt power supply for fixed operation.
Stay tuned...........

I seem to have a penchant for converting junk Heathkit slopbucket xmitters to usable HIHIHIFI AM xmitters.  I did an HX-20, HW-12, and a SOB-400.

Jay, let me be among the first to welcome you, both here on the website and hopefully soon on the air.

What will be your lineup?

Can sked on 75 and 40 very easily, let me know.

The 32V2 I used to chat with folks 15 years ago. It saw fit to transmit on three frequencies...at the same time! Kinda gave simulcasting a bad name on 75.  ::)

This is the same transmitter that showed me how "100 watts is pissweak when the band is busy", making it instrumental in my AM-education process. 

I'll get back to it someday, really I will....

Looks like you are qualified for a job as a Greeter at Wal Mart! Getting ready for that second career, eh?

Viking II with a solid state modulator - 200% positive peak modulation.

That's great!  Some of those early mobile rigs would really be fun to get back on the air on Am.  I have a Subraco mobile xmtr that I should be getting on one of these days, also an old Stancor mobile rig and an interesting Micamold novice-type 6L6 rig that might be fun to hook up to a little plate modulator and fire-up on Am.  All of these rigs are, of course in the PW category, but still a lot of fun.  And.....for that matter I could always crank them into the pr of 3-500Z or the 4CX1500B after-burners to ensure that I am heard.  Also...it is really neat to fire-up something on the air a little different than the same old stuff that everyone else is using...like Valiants, Viking IIs, DX-100s, etc., etc.  ;D

73,  Jack, W9GT

My most unusual rig was a PW 10M AM mobile transmitter I built when I was 14 years old in 1959.   I installed it in my father's 1955 Pontiac, ready and waiting for me when I became 16.   The transmitter itself was not unusual, it had a 6AQ5 final, a 6AQ5 modulator, a carbon mike drove the modulator directly (made from a telephone handset) and a 12AU7 for the crystal oscillator and multiplier, for a total of three tubes.  The modulator used the primary of an output transmformer as the modulation choke.  What made it unusual is that the schematic for it was read to me over the air on 10M AM.   Whoever I was talking to, described the circuit and I drew it on the blank side of the ARRL log book sheet.   I just checked the log book, and there is no indication which one of the QSO's logged was the one describing it.   I built it from the crude diagram in the log book, connected it to the car receiver B+ and filament supply and it worked!   I used it in my teenage years until I went away to college.   Then I used it as a portable at my parents house when visiting them.   I used it as my high school senior physics project, the teacher was a ham, I only got a B because he realized that I didn't make it just for his class.   I also used it for a project in my mechanical drawing class, finally making a decent schematic drawing from the scribbled drawing in the log book.   To this day I don't know where the design came from, anyone have an idea.

My teacher in 10th grade shop made an AM Hartley rig out of a 6J5 and a carbon microphone using loop absorbtion modulation - that was cool.

That AC/DC 50C5 rig that I did a while ago was a fun (if a bit dangerous) rig to use on 160M.

Mike WU2D

Working on a Sonar 75B Marine Radiotelephone.  Going to use it on 3880 and 3885 in my pickup.  Got it for $25.

SB-10, SSB Adapter, driving an Apache, with full carrier inserted for DSB AM or AM on either sideband. Also SB-10 (powered from the Apache and VFO driven from the Apache) driving an SB-200 amplifer using full carrier inserted for DSB AM.

I can't believe that I forgot to mention my John Meck T-60-1 transmitter!!!  This is a rare 1947 vintage rig that runs a pair of 6L6s modulated by a pair of 6L6s.  Built by John Meck Co. in Plymouth, Indiana....it has a local connection.  The schematic indicates that the engineering offices were here in Ft. Wayne.  It runs about 35 watts out and is a really classic design with feed-thru insulators on the front panel, of all places, for the antenna connections.  It uses B&W plug-in coils and link-coupled balanced output.  I ran this rig as a demonstration of vintage AM at field day this year along with a similar vintage NC-240D receiver and had a blast with it.  Worked a lot of SSBers cross mode and they never knew the difference!  I posted a couple of pictures of it on my web pages (address on QRZ).

73,  Jack, W9GT

My most unusual REGULAR rig is an R/T-427, has 17 tubes and a built in dynamotor for B+ voltage. Runs on 28 vdc at about 8 amps and outputs slightly more than 10 watts. Has a real cool mechanical memory to retune the tuned circuits when the frequecny is changed.

I have used an old R.F. Generator with AM & FM modulation built in once or twice but you don't make many QSOs on that. That is a real QRP rig.

90 watts into a 12DQ6  seems to be .. umm ..  pushing it a bit. I have a 50W marine rig here with a single 12DQ6  which seems closer to the makrk for commercial service?
                                                                            Ian VK3KRI

Well thats 'cause  American watts are smaller than Canadian watts....    klc

Never built or operated on, but in a handbook in my Jr. High library there was a diagram for a two meter AM transceiver that used a single type 76 tube.  Anyone else ever see this?

On 160 and 75, the dulcet tones on my end are with  a R-390A and the homebrew 2x304TL (Class C RF) 2x304TH (Class B2 mod) exhaler. 2500 volts using a power transformer from a Gates BC1-H1 and mod iron from a Gates BC-5.

If the QRM is easy, I'll use the ART-13.

Hey, I'm 1,500 miles from most of you 1, 2 , 3s and 4s. Real Dog X-Ray.

Pre war Halliicrafters  HT-9. One of the niceest looking rigs I have ever seen.
814 excited by a 6L6 and modulated by 4 - 6L6s. Spererate power supplies for the exciter, modulator and PA
(http://home.comcast.net/~chnord/HT-9.JPG)

That is really a cool rig Carl!  I believe that Bob, W8MNQ in Port Huron, MI has a couple of HT-9s.  You might want to drop him a note or catch him on the air.

73,  Jack, W9GT

Don't tell me that's the one from Maine, I might have to jump off a bridge. That thing is nice!

OK
I won't tell you.......  ;D