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FYI: Gated BC1-G went cheap!




 
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Author Topic: FYI: Gated BC1-G went cheap!  (Read 20038 times)
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flintstone mop
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« Reply #25 on: December 17, 2014, 04:53:49 PM »

The mad rush to convert the AM's to AM-HD is dead in its tracks. So, the old analog TX's will be in service until there are no more watts to emit.
AM-HD is really amazing audio. Just like FM, and it travels much better than FM-HD. The multi-path driving in a city and buildings kills FM-HD.
The AM-HD was poorly conceived and caused a lot of interference at night. Most of those HD signals are off now. They shudda moved the AM's where the old analog TV was.
Fred
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Fred KC4MOP
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« Reply #26 on: December 17, 2014, 05:47:08 PM »

The mad rush to convert the AM's to AM-HD is dead in its tracks.

Once the FCC finishes sorting out comments from the recent AM revitalization NPRM, I believe we'll see them force AM to all-digital operation in the next few years. I don't see too many other ways for them to fix the present mess.

73,
Jim
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wd8das
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« Reply #27 on: December 17, 2014, 07:48:06 PM »


Our flagship station runs a B.E AM-6A transmitter.  I like it -very reliable and good performance - but it doesn't have the same romance as the tube rigs.  And for hobby purposes that romance is important. 

Plus there are frequency-determined parts on every module, greatly complicating a conversion to the ham bands.  I bought an AM-1A transmitter on eBay for a song in the hopes that it could be a second backup to the AM-6A.  Its control and driver boards are useful, but the RF/Mod module can't be used directly as it is set up in another part of the broadcast band. 

Steve WD8DAS

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John K5PRO
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« Reply #28 on: December 17, 2014, 08:57:12 PM »

I parted out a LARCAN 44 kW channel 11 rig a few years ago. It had the 1980 MOSFETS in giant slide in heat-sunk plates, that could be swapped out. Lots of them. There may be one or two left, the rest were scrapped along with the cabinets and power supplies. All the coax combiners, splitters, phase shifters, diplexer, aural cavity, etc were kept, and reused at the particle factory for 200 MHz, very useful pieces. Lots of 3 inch and 1 5/8 inch rigid line too. 
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John K5PRO
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« Reply #29 on: December 17, 2014, 09:00:24 PM »

Same thing can be said for the Omnitronix rigs, lots of trouble to move them up past top band. They built a tropical model, but I'm not sure how well it worked. I designed the PDM modulator for that line, under contract, in the 1980s.
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KA3EKH
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« Reply #30 on: December 18, 2014, 09:25:54 AM »

More thoughts about tube broadcast transmitters and why anyone would value them.
I canít imagine anyone running a tube transmitter in commercial service these days, least not at the one of five kW level. I had couple sites with old Harris MW-5 transmitters as primary and backup and the one thing you could count on was every year you had the change out the modulator tubes with the PA having to be replaced once every two years so after ten years you were looking at close to the replacement value for the solid state. Back around the late nineties and early part of two thousand both sites were converted over to DAX-5 transmitters and then all of a sudden no more tube changes! The only issue is the new Harris has no tuning or load controls and is designed for 50J0 and if you donít have that bad things happen. On a sister station where one is installed they had to remove it and replace it with a BE AM-6 being that was capable of working into their flakey pattern. Looking at the revenue from our AM stations would think that if we had to purchase a new transmitter or go HD the company would just turn in the licenses. With automation and all solid state transmitters you can run an AM property for little more than the cost of utilities but unless youíre in a top market the land that your tower farm and transmitter site occupies is worth more than any revenue the station generates.
Just canít see much love for the current generation of solid state transmitters and think when they go off line they will end up just being used for parts. Just donít see someone getting a Harris DAX and modify it for Ham use. Maybe the old tube transmitters were something like the steam locomotives? Difficult to keep running, temperamental and labor intensive but just like steam they have a certain feel or romance about them so thatís why we save and occasionally use them where the solid state more along the line of a diesel and who cares about diesels?
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flintstone mop
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« Reply #31 on: December 18, 2014, 12:17:48 PM »

The attraction to tube transmitters for the Ham community may be the last bit of nostalgia that is easily converted to the Ham bands without major brain pain. Today's solid state stuff is not so easy to move and that's the nature of the beast. The reliability of solid state has put a lot of engineers out of work.
So poo poo the tube transmitter and its need of TLC. That was the beauty of it. WABC, 770, probably had an engineer on duty 24 hrs a day to keep that ole G.E. humming. They brought a Harris MW-50 online and they said it never sounded like the G.E. plate modulated rig. Something about feeling the bass notes on the concrete floor from the modulation transformer. Some newer engineers do not like the beauty of tube equipment. Turn it on, look at the meters, and lock up the site.

An odd-ball transmitter that has tubes:
There was a Collins tube B'Cast TX (Collins 820D) typical Collins engineering, that was not so friendly to move. Mike Dorrough had a couple of articles in ER magazine describing the miseries of moving the TX to 160M.
Fred
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Fred KC4MOP
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« Reply #32 on: December 18, 2014, 05:49:45 PM »

Looks like you have another chance, just saw it on QTH. Relisted this morning

The add now says a sale is pending.

Bill
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KB5MD
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« Reply #33 on: December 18, 2014, 07:26:12 PM »

Got my Collins 300G 8 miles from the shack.  Piece of cake to move (after we got it out of the transmitter room.)
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KX5JT
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« Reply #34 on: December 19, 2014, 09:06:48 PM »

That's awesome Dr. Roy! I wonder how many people who run converted broadcast transmitters might have actually listened too (regularly) the same transmitter when it was being used in a broadcast station.  That would be really cool to obtain a retired one from a previous favorite station.
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AMI#1684
flintstone mop
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« Reply #35 on: December 28, 2014, 09:27:40 PM »

A Gates BC1-G in Greenwich, CT may be available again. As the first two times, the buyer would be responsible for the removal of the entire transmitter from the site. A spare set of tubes (833 and 807) plus some spare parts would also be included.

The deadline of Jan 5 might be a show stopper.
Fred
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Fred KC4MOP
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Brrrr- it's cold in the shack! Fire up the BIG RIG


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« Reply #36 on: January 05, 2015, 07:10:04 PM »

Yes, it is true!
The same Gastes Beastly Sea One-Gee sold yet again on Epay. For $201 bux!

Almost bid on it myself, but lacking certain information or means of contact, I restrained myself.
A bargain to be sure.
Assuming you could go and get it.

Was going to pack my oxy-acetylene cutting rig and sawzall to reduce the weight of individual componenets,
and to speed load out. At least that was the thought coursing through my mind.

On another note, a fellow with a neat looking Racal receiver - looking like a 4" high R-390 - did NOT sell it for $449, so he just
relisted it. This time for $559. Yah, that works for me. How 'bout you?  Tongue
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Tom W2ILA
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« Reply #37 on: January 06, 2015, 05:40:14 PM »

As hams age the want for a BC transmitter in the shack will INCREASE.
1) clean it with a hose rather than Q-tips. Poor eyssight really does not do well with Q-tips. Q-tips needed for ear wax.
2) no more lifting.  You stand and work in the transmitters rather than sit with them precariously balanced on a bench.
3) 160 meters - nobody's home. Plenty or room for those 16kc wide signals without an ssb net halfway across the country stirring the nest.
4) toobs - troubleshoot with and panel meters rather than tiny LCD newfangled chinese-made computer thingys.
5) warmth - when oil shoots up again in price you'll be glad you have auxiliary electric heat that doubles as a transmitter.
6) transport with a pickup truck requires you to have a pickup truck.  Everyone loves trucks.
7) can use as a boat - covered in earlier post.  Important as climate change raises sea levels.  Toolshed when not floating.
Cool makes any mic sound good.
9) Woman aren't saying "it's so big!" to you?  They will after you move the transmitter into the living room.
10) Surely there are more good reasons.  I love my Collins 300G


* 300g.jpg (355.88 KB, 1280x1240 - viewed 276 times.)
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KB2WIG
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« Reply #38 on: January 06, 2015, 08:07:10 PM »



It looks very comfey in the living room.

klc
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WBear2GCR
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Brrrr- it's cold in the shack! Fire up the BIG RIG


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« Reply #39 on: January 07, 2015, 08:54:00 AM »


Shiny too...

"...man's best friend..."??


The other angle I had on the Gates is that it looked like the cabinet, sans guts was perfectly suited for conversion.
Conversion to a very nice over and under refrigerator. Something any XYL would love to see everyday in the kitchen!

Look at it, perfect, just splice the front panels to the door skins of a properly selected and sized refrigerator!!

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ka4koe
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It's alive. IT'S ALIVE!!!


« Reply #40 on: January 08, 2015, 08:22:52 AM »

You're living the good life, bro.
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I'm outta control, plain and simple. Now I have a broadcast transmitter.
WBear2GCR
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Brrrr- it's cold in the shack! Fire up the BIG RIG


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« Reply #41 on: January 13, 2015, 02:45:31 PM »


Apparently it is back again, this time with an increase of $100 in the starting price.

As the now classic song says "...should I stay or should I go?..."
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Patrick J. / KD5OEI
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« Reply #42 on: January 14, 2015, 12:39:46 AM »

Don't the CBers know the 833's don't like 11 meters so much?  Or don't care.

pricing up.. a guy I know sells used tubes. He couldn't get $5 but when he started listing them for $25 he got people buying them. Apparently some people think that a low price always means junk. If the BC rig seller's hoping to price it up above CBers, he may have a shock, as they'll spend foolishly.

I have a van, so I got no problem getting something that size. Moved two BTA-250L's, those weigh 1300 lbs.
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WBear2GCR
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Brrrr- it's cold in the shack! Fire up the BIG RIG


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« Reply #43 on: January 14, 2015, 02:22:35 PM »

Socket set, wrenches, sawzall w/metal blades, ox-acetalyne cutting torch... moves easy! Cheesy

I still favor the "refrigerator mod"...

                              _-_-

PS. if the outfit handling the sale had contacted me, it would have been picked up and moved a
few weeks ago...fyi, fwiw, and all that jolly good stuff.
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John K5PRO
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« Reply #44 on: January 15, 2015, 03:56:45 PM »

Crap, I feel older now, that tube FM transmitters are being pulled out of service. I was designing SOTA tube FM rigs for BE from 1981-85 in Quincy, down the street from the Gates/Harris Tin Works. Damn silicon has taken them away.
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John K5PRO
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« Reply #45 on: January 15, 2015, 03:57:59 PM »

I just sold off my BC-1H1 as I needed the space and it wasn't getting any attention since I got it, still on 1190. Hopefully it will pop on the air from upper Wisconsin sometime.
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KA3EKH
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« Reply #46 on: January 16, 2015, 08:41:34 AM »

Hope you did not have anything to do with the FM-30 and that squirrely grid input tuning mess! Or the IPA system that used an entire rack full of junk to do what Harris did in one brick size amplifier?
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John K5PRO
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« Reply #47 on: January 16, 2015, 02:31:02 PM »

Well, thanks for your comments! Did you have an FM30 or FM30A or FM30B? I was there when the first FM30s were going out the door. I had just joined the company. I changed out the stoplight controller 1 bit microprocessor controls to CMOS logic with a later Z80 add on for logging. The original grid circuit was quite narrowbanded, and it took a while for them to convert over to more broadbanded. I developed the FM3.5, FM5, and started on the 10 when I departed Quincy for the east coast. These had the first of the broadband input design, where we switched to a microstrip board to do most of the Z transformation, and only used the inductive slider to resonate the grid/cathode capacitance. At the time Harris had nothing of this sort. We are neck and neck competitors in the 1980s with them.

For the IPA, not sure about what you meant by a rack of junk? Was it a rack full? The first FM30s had CTC BM100-28 or something like that, aluminum metallization bipolars, 2 per board, and had 4 boards plus a driver, it was mounted horizontally on the lower front of the cabinet. It had a big 3 phase linear supply. It was an ugly and unreliable thing with mica trimmers all over the place. DMOS transistors were not yet available to do a broadband IPA, so my design started with the TRW TP9383 150 watt bipolar and later switched to the ST Thomson SD1460 BJT. A pair of either made a 250 watt semi-broadband amplifier (10 MHz max BW). It was a big blue drawer, with built in linear regulator and power transformer, 28 VDC. I know that they stacked those drawers for a while in their products. At the time, Harris didn't have a single brick IPA either. That took a while, and Bob Artigo, Bobby McDonald and others (ex CTC) developed a line of blue 700 watt modules that Harris, Continental both bought to use as IPAs. Harris may have then built their own at the time. BE later (after 1985) went to DMOS drivers, and I have no idea how that was packaged into their transmitters.

BE's claim to fame in FM was the half wave output circuit, that didn't have sliding contacts or a blocker capacitor. That was a piece of work, and we were very proud at the time. There were those who said the stored energy in a half wave resonator (high Q) would degrade the FM wideband signal, but I proved this wrong in experiments, both grounded grid and grounded cathode 4CX3500A, in a paper I wrote that later became part of the 7th edition NAB handbook FM chapter by Mendenhall.

I still use half wave circuits where I can, due to the simplicity of tuning with a bellows or cap at the end instead of a scraping finger contract on a wall.
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KA3EKH
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« Reply #48 on: January 16, 2015, 04:38:33 PM »

The FM-30 I think is a 30B with the blue amplifiers and is located at WSCL in Seaford Delaware. Along with there now retired engineer Bruce have been working on that transmitter for all of the thirty years it has been installed when new. Not many parts that have not been replaced or issues itís not had. Replaced the entire grid input tuning section for the PA about twenty years ago and have to give some credit being it has been in operation now continually for thirty years with no backup and limited regular maintenance. They are going to replace it soon and have recommended a Nautel but have to wonder what that would look like in thirty years.
Also have a FM-10 as a backup in another site but thatís the newer tan version that sounds like a water pump when the filaments come on.
Imagine the design of the PA cavity is why they never tune like any other transmitter; lack any type of plate dip or anything like that.
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John K5PRO
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« Reply #49 on: January 18, 2015, 05:45:56 PM »

30 years on that rig is pretty good. The grid circuit has to be cleaned occasionally, esp the tuning sliders, as it is true for Continental, Harris, and the rest. Fine dust gets through whatever air filter there is, and settles there. I think the solid state rigs will be fine, but they too must be cleaned. At least they don't have the HV to attract dust and flash over.

FM10 sounds like it has a bad blower bearing if it sounds like a water pump! Have you tried a little oil at the motor, or are they sealed? I can't remember if the 10 had the cylindrical 'stovepipe' cavity circuit or the big box like the FM30?

As for plate dip, I think most of the cavity circuits like that didn't act like a typical 6146 and pi network. The plate dip is ever slight when loaded correctly, and it is more important to watch for peak screen current when tuning. If the efficiency is lousy, then adjust the loading and retune plate. We always used screen current peak. BTW, screen current on a tetrode in class C or B is very sensitive of loading as well as VSWR. Thats why the VSWR foldback circuit in the BE's worked to keep screen current from overloading when icing up happened on an antenna.

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