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OM's 1946 AM Rig About To Be On Air




 
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Author Topic: OM's 1946 AM Rig About To Be On Air  (Read 25182 times)
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Tom WA3KLR
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« on: August 07, 2005, 08:03:17 PM »

My father Paul W3VVS is finishing re-furbishing his late 1940's homebrew AM transmitter.  Hopefully we will hear him on 75 meters within a couple weeks.

The transmitter is a pair of 812H's push-pull in the r.f. deck, driven by an 807 crystal controlled exciter deck.  Pair of 807's in modulator deck and a power supply deck.

Let's see if this new photo feature works:


* 2005_0223Image0009.JPG (121.36 KB, 640x480 - viewed 1356 times.)
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« Reply #1 on: August 08, 2005, 11:22:45 AM »

Let's see if this new photo feature works:

Your piccie must reside on a public server with a publicly accesssible URL.  Posting a pic off your hard-drive won't work.   Maybe if you email your pic to Gary, he can post it somewhere on  Amfone.net somewhere, where it can be accessed?
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« Reply #2 on: August 08, 2005, 12:05:05 PM »

www.photobucket.com is a good free image hoster.
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« Reply #3 on: August 08, 2005, 02:51:56 PM »

You can post pictures from your hard drive. Click "Additional Options" below your message box when adding a message. Here's one from my hard drive:



* antennascope.gif (2.13 KB, 285x243 - viewed 1060 times.)

* BareStand%202.jpg (5.67 KB, 144x177 - viewed 904 times.)
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Tom WA3KLR
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« Reply #4 on: August 08, 2005, 08:40:30 PM »

Pete,

Thanks for the tip.   The rig picture is now added to the original posting.

Everyone,

Please scroll back to the top and see the photo edited in to my original posting.

Thanks,
Tom
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« Reply #5 on: August 09, 2005, 07:01:15 AM »

*That* is a thing of beauty, Tom.  Glad you're getting it back on the air!

73 John
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« Reply #6 on: August 09, 2005, 09:26:36 AM »

Tom,
      I can't wait to hear it on the air! I had a conversation with your father about the modulation scheme (with the pair of 807's) and am very anxious to hear how it sounds.

The mod scheme is very typical of what a lot of Hams were doing right after WWII.

Thanks for posting the pic and hope to mod-u-sooner-than-later.
Joe Cro N3IBX
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« Reply #7 on: August 10, 2005, 07:53:25 PM »

Like a good motor real rigs are painted black!
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« Reply #8 on: August 14, 2005, 02:09:35 PM »

Cool
Fire That Mother Up!!!
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« Reply #9 on: August 14, 2005, 04:24:54 PM »

As I always say, "Nothing is sexier than Black Crackle and Green Phospher."

Congrats Tom, that rig pretty enough to make a grown man cry.
Its great he could get it back on the air, 60 years later.
Looking forward to hearing it this fall/winter.
Perhaps you could post some interior shots, would love to the details.

As the old bromide says...Everything old becomes new again....
Or in the modern words of the Timtron "Nothing like it, old technology."
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Tom WA3KLR
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« Reply #10 on: August 15, 2005, 02:16:35 PM »

I guess I will make an old-time radio serial out of this topic.  Below is a rear view of the 812H rack cabinet just before refurbishing began in February 2005.

Tonight’s episode – The Shack Overview.

By the early 1950’s my father had 3 home-brew HF transmitter racks in his shack on the second floor of our “Cape Cod” in the northern suburbs of Philadelphia.  When my twin brother and I were teenagers about 1968, my father moved the ham shack to the basement (where it resides today) so that my brother could have his own room.  Fred moved into the old ham shack and promptly painted it hyellow.

Anyhow, the original shack in the second floor had a workbench area in addition to the operating area.  There was a 3 ½ foot rack cabinet immediately to the right of the operating desk and a 3 ½ foot rack cabinet immediately to the left of the operating desk.  To the left of that rack cabinet was a 2 ½ foot rack cabinet with a 160 meter 90 Watt AM transmitter.  All 3 rack cabinets are on castors.  (I’ll see if I can dig up a good photo.)

The 160 meter rack (2 ½ foot) consisted of an r.f. deck using an 811 or 812 with a 6AG7 crystal oscillator/driver, a modulator deck using a pair of 6L6s, and a power supply deck.  This rack of equipment was given away to a boy scout group mentored by one of our radio club members when the shack was moved to the basement.  The modulator deck actually returned a few years ago, somewhat rusty.

The 3 ½ foot rack cabinet just to the left of the operating desk was the big HF AM rig, 300 Watts input.  The r.f. deck is a pair of 812H’s in push-pull.  The 812H was solely made by United Electronics Company (UEC) of Newark, NJ.  The plug-in final tank coils are war-surplus BC-610 spares that are modified.  The final is criss-cross neutralized.  The driver coil is the plug-in B&W JVL series.

The plate input power is 1500 Volts at 200 milliamperes.

In those days, the final r.f. deck was driven by an 815 buffer deck driven by a Meissner Model EX Signal Shifter (VFO).  We don’t know what happened to the buffer deck!  Originally, my father had an earlier model Signal Shifter which used a 6L6.  This earlier model Signal Shifter drove the final by itself o.k.  When my father upgraded to the new Model EX instead of the earlier model, he found that the EX put out LESS power, even though it used an 807 instead of a 6L6!  Hence the 815 buffer deck was added.

The EX was the last in the line of the Signal Shifters, but by far the most handsome of the series, in my opinion, with its brushed aluminum front panel and magic eye tube.  The EX sat at the left end of the operating desk.

The push-pull 807 modulator deck design is from a 1940’s ARRL handbook.

The power supply deck and the modulator decks again use United Electric sole parts; Z-225 mercury rectifiers.  They are electrically similar to 866A’s, but are shorter with the T14 bulb.  This helps to keep the panel height down.

The high voltage transformer, filter chokes and oil filter capacitors were all war surplus.

The Meissner EX Signal Shifter was sold off, probably when my father bought a Ranger II in 1967 (which he still runs).  I don’t know if he expected to ever drive the final with the Ranger, but perhaps he felt he would never run the 812H rig again.  The Ranger then sat at the left end of the operating desk instead of the Signal Shifter.  This was all well and good for me for when I became a JN in 1968.  All I needed to do was order some 75, 40 and 15 meter novice crystals for the Ranger and plug them in.  I still have those crystals.

To the right of the operating desk was a 3 ½ foot rack cabinet with a 50 Watt 10 meter AM transmitter.  The 10 meter r.f. deck has a 6F6 crystal oscillator, 6L6 buffer/multiplier, and 807 final with a 6L6 keyer tube.  All coils are plug-in.  This deck is now the exciter deck for the 812H rack refurbishment.

The 10 meter rack cabinet also had a homebrew 6 meter AM r.f. deck.  The final used a 6146.  This deck was built with horizontal orientation.  The panel height was only 3 ½ inches.

There was a push-pull 6L6 modulator deck and a power supply deck also to this rack cabinet.  The rack was primarily used on our radio club frequency of 29.493 MHz. AM.  The 6 meter deck was hardly ever used. 

The Phil-Mont Mobile Radio Club established 29.493 MHz. as their “Channel 1” frequency due to the war surplus FT-243 crystals on 7373.333 kHz.  Phil-Mont was active on this frequency from 1949 until the migration to a 2 meter FM repeater on 147.030 MHz. in the early 1970’s.  For a period from about 1968 until the 2 meter repeater was put in service, the club had a 10 meter AM repeater, split-site, about 1 mile apart in the Roxborough section of Philadelphia.  The repeater work has been mostly the sole efforts of Jim Spencer W3BBB, to this day.

After the shack was moved to the basement, and the 10 meter 50 Watt AM transmitter was not in use any more, I decided one day to try to fire up the 812H rig on 29.493 MHz. for kicks; 200 Watts AM out. This was circa 1970.  I wasn’t on the air more than a couple minutes and the next door neighbor Millie called on the phone to complain about interference on her telephone.  That was the last time the 812H rig was on the air.

I brought the other remaining empty 3 ½ foot rack cabinet to my house when I moved here in 1990.  I hope to build up a Class E legal limit AM transmitter in it.

Next episode – The Operating Desk/Receivers

Below is a rear view of the 812H rack cabinet just before refurbishing began in February 2005.


* 2005_0223Image0003.JPG (122.29 KB, 640x480 - viewed 1087 times.)
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Tom WA3KLR
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« Reply #11 on: August 15, 2005, 07:47:00 PM »

Close-ups of the rear of the un-refurbished rack:

1. The r.f deck

2. The exciter deck

3. The modulator and power supply decks.


* 2005_0223Image0007r.JPG (24.1 KB, 538x474 - viewed 967 times.)

* 2005_0223Image0006r.JPG (39.39 KB, 640x480 - viewed 921 times.)

* 2005_0223Image0004r.JPG (49 KB, 640x480 - viewed 928 times.)
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« Reply #12 on: August 16, 2005, 12:10:59 PM »

More photos:

1. RF deck close-up

2. Modulator deck close-up


* 2005_0223Image0024.JPG (45.36 KB, 639x479 - viewed 895 times.)

* 2005_0728Image0003r.JPG (44.35 KB, 618x440 - viewed 953 times.)
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« Reply #13 on: August 16, 2005, 12:15:06 PM »

There are 6 crystals in the exciter deck now, all for 75 meters:
3837, 3870, 3875, 3880, 3885, 3890.  BCNU.

Crystal-controlled 807 Exciter Deck Photos:

1.  Top View

2.  Bottom View


* 2005_0619Image0005r.JPG (38.88 KB, 587x477 - viewed 980 times.)

* exciter_bottom1r.JPG (59.31 KB, 639x479 - viewed 897 times.)
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« Reply #14 on: August 16, 2005, 12:21:13 PM »

Excellent story and great photos, Tom.  Thanks and please keep 'em coming!
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« Reply #15 on: August 16, 2005, 01:10:04 PM »

Tonight’s episode – The Operating Desk & Receivers

The operating desk acquired in the early 1950’s has a bit of broadcash history with it.  Two neighborhood radio hams who were broadcast engineers at WIBG-AM, George Hooper and Lester Sacks (both SKs now), gave to my father the old engineering console from the broadcast transmitter site in Flourtown, PA, which is just west of the northwestern border of Philadelphia.   (WIBG started out in Glenside, Pa. off of Keswick Avenue as a small religious station - Why I Believe God.  In the baby boom era of the 1960’s, WIBG was the #1 rock music station in the Philadelphia market, transmitting on 990 kHz.  It was affectionately known as “Wibbage”.  By the early 1980’s, this station reverted to Christian music, WZZD as I recall.  Now, 990 is a talk radio station.)

 The desk is a large, heavy metal office desk with a thick black rubber top.  The sloping panels above the desktop went to another ham friend, Jim Spencer, who in turn built a short height wooden equipment shelf to sit on the desk top.  The wooden shelf is designed to take (3) 3 ½ inch rack panels side by side on the front face.

As I recall, the left-hand rack panel and right-hand panels were identical.  They contained volume and squelch pots, switches and pilot lamps controlling crystal-controlled monitor receivers.  The left panel went to a Link 11-UF n.b.f.m. receiver on the local township police frequency of 39.18 MHz.  The right panel went to the 10 meter AM receiver on 29.493 MHz.  The 10 meter AM receiver and Link f.m. police receiver sat on a shelf under the desk.

The center panel has a symmetrical lay-out of 2 main power switches, two classic telephone lever switches, and 4 pilot lamp assemblies.  Two lamps are standby power indicators which come on when the power switch is up.  The other two lamps are transmit indicators which light up when the lever switches are thrown.  The left-hand controls are for the 812H rig to the left of the desk.  The right-hand controls are for the 10 meter AM transmitter to the right of the desk

If either lever switch was thrown, up to 4 receivers were muted.

The muted receivers were:
- the main HF receiver, a  Hammarlund HQ-129X purchased new in 1946
- a home-brew 10 meter AM crystal-controlled, squelched receiver
- a 10, 6 and 2 meter AM and FM receiver using a RME VHF-152 tunable converter 
  feeding a homebrew i.f. receiver with AM and FM modes.  The i.f. receiver was built in
  a cabinet that matched the VHF-152 cabinet.

So occupying the top of the shelf on the operating desk were, from left to right, the Meissner Signal Shifter (or later a Ranger II), the HQ-129X, and the RME 10, 6, and 2 meter receiver cabinets.

The 10 meter AM receiver and the Link police receivers were on a time-clock that powered the receivers from about 4:45 p.m. to 11 p.m. every day.  These two receivers also fed several remote speakers in the house.

About 1969, the HQ-129X receiver was sold after acquiring a new-in-the-box, never used National NC-183D.

The photo below of the operating desk was taken today, August 16, 2005:

On the operating desk shelf is an RME69, the NC-183D and the Ranger II.  The 812H rig will be used with the NC-183D receiver.  The 812H rig will be controlled by the right-hand set of switches of the center control panel.

Also, the left-hand control panel has been replaced to fill in the spot.  The current 3 ½ inch panel is from the old 6 meter Link f.m. receiver that was on 52.525 MHz.   The left-hand meter movement is a zero center meter connected to the discriminator.  This showed the received signal’s frequency relative to the center of the receiver channel.  The right-hand meter was connected to the 1st limiter grid.  This meter showed the relative received signal strength.

All for now.


* 2005_0816Image0006.JPG (120.45 KB, 640x480 - viewed 1091 times.)
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« Reply #16 on: August 18, 2005, 05:42:13 PM »

I found a negative of the old second floor shack desk and scanned it in.  (Not too bad of a rendering for a reflective scan of a negative.)

At the left end of the operating desk is the Meissner Signal Shifter Model EX (vfo) which drove the 812H rack.  The JT-30 microphone for the 812H rack (just to the left of this photo) is in front of the middle of the EX panel.  Sitting on top of the EX is the official Hammarlund speaker for the HQ-129X.

To the right of the EX is the Hammarlund HQ-129X receiver. 

To the right of the -129X is the RME VHF-152 10, 6 and 2 meter tunable converter.  To the right of it is the home-brew a.m. and f.m. i.f. receiver for the VHF-152, built in a matching cabinet.  On top of the i.f. receiver cabinet is a Heathkit Two-er, built for the local township Civil Defense RACES operations.  (Duck and cover!)

To the right of the i.f. receiver, which is the last item on the desktop, is the 10 meter 50 Watts AM transmitter rack cabinet.  Only the top deck of the rack can be seen.  It is now the exciter deck for the present 812H rig refurbishment.  Sitting on top of the rack cabinet is a National FB-7 receiver and a Vibroplex bug.  The JT-30 microphone for the 10 meter rack is sitting in front of the i.f. receiver cabinet.

Back at the left side of the desk, in front of the telephone on the pull-out shelf is a portable typewriter in it’s case.  This may have been called a laptop in it’s day – HI.

When we get the transmitter going on the air, I will take another picture of the finals.  This time the dust is cleaned off of the tube envelopes and the filaments will be lit!  And I will have some “operator with rack” photos.

- This photo taken April 1965 - (see the desk calendar on top of the -129X!)


* w3vvs_shack3ccr.JPG (98.09 KB, 1004x898 - viewed 997 times.)
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« Reply #17 on: August 18, 2005, 06:23:41 PM »

Nice looking rig Tom .
Give us a heads up and we'll  roll tape on the inaugural key up.

We could alos take this great thread and turn it into a cover story Amfone. Nice project!


And yes you can upload from your machine. No more needing a pic on a url to post .

It was one of the bigger points in the decision making process.
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« Reply #18 on: August 19, 2005, 08:38:38 AM »

Gary,

Thanks very much for the offer to record on-the-air transmissions from W3VVS.  We may be testing today or tomorrow, then are ready to go full QSO.  I will post a QSO notice here for everyone and send you a PM.

Thanks also for the ability to post photos and files from the hard drive.  This is a great feature!
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« Reply #19 on: August 21, 2005, 03:57:59 PM »

W3VVS will be on the AWA AM net today (Sunday) at 4:30 p.m. on 3837 kHz. with his homebrew 1940's refurbished 812H rig.
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« Reply #20 on: August 21, 2005, 10:11:40 PM »

The inaugural transmissions of W3VVS' refurbished 300 Watt 812H rig went very well today on the AWA net, 3837 kHz.   He sounded good and clean to me. 

Gary, thanks again for making the recordings of the AWA net. 

I will get to my father's house soon and do some operating from there with the rig.  I hope that there is no interference to the neighborhood!  We can get on 3870, 3875, 3880, 3885, and 3890 also.
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« Reply #21 on: August 22, 2005, 06:53:54 PM »

Tom,

I have spent quite some time carefully examining the pics.  They're wonderful!   Your dad is to be congratulated!  BTW, it was a pleasure to talk to you and Wayne this afternoon.  Hope to hear Dad on the AWA Sunday.  Sorry I couldn't be there yesterday.

73,
Herb
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« Reply #22 on: August 27, 2005, 07:24:20 PM »

Thanks for the comments Herb.  I gave my father a print-out of this thread today.


2 photos taken during today's visit and operation of his station:

1. The shack view with the 812H transmitter rack.

2. Close-up of the push-pull final PA with the 812H's lit up.


* 2005_0827Image0004r.JPG (55.06 KB, 640x480 - viewed 790 times.)

* 2005_0827Image0014r.JPG (68.63 KB, 640x480 - viewed 798 times.)
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73 de Tom WA3KLR  AMI # 77   Amplitude Modulation - a force Now and for the Future!
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« Reply #23 on: August 30, 2005, 09:02:21 PM »

Final Episode - Photo Op.

O.K. here is my final posting on this topic.  Below are 2 photos of my father Paul, W3VVS at his operating desk.  One photo was taken approximately 50 years ago.  We finally found 1 photo that shows the original 812H transmitter rack to the left of the operating desk.  The other photo was taken last week operating with the refurbished 812H transmitter rack, to the right of my OM.

1. Second floor shack, circa 1954.  812H rack to left of operating desk.

2. Basement shack, August 2005, 51 years later.  Refurbished 812H rack to right of W3VVS.


* w3vvs_c1954r2.JPG (99.57 KB, 947x608 - viewed 904 times.)

* w3vvs_082705m2.JPG (114.34 KB, 639x479 - viewed 945 times.)
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« Reply #24 on: August 31, 2005, 11:53:02 AM »

Very nice Tom.  That's really great.  Regards to the OM.

K2VHerb
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"Just because your voice reaches halfway around the world doesn't mean you are wiser than when it reached only to the end of the bar."
--Edward R. Murrow
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