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RME Transmitter: Help needed




 
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Author Topic: RME Transmitter: Help needed  (Read 3281 times)
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KD2AZI
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« on: September 07, 2019, 08:46:29 AM »

All, I'm on a research quest before restoration.  I've scoured the 'net, catalogs, QSTs, handbooks, adverts, other web forums, radio doc specialists...Zilch.  The Only mention of any RME transmitter was on AMfone, and I've reached out to the poster. 

RME Model RT-175, tube complement are Taylors, and T-55 is the final.  Has plug in tank coils (I have two) and those aluminum knobs are mounted on plug-in cans, a different set for each band, and I'm missing a few.

It came from a local NJ SK estate with a tag reading: "1939 Transmitter."  It was owned by W3IBI, Dr. Ben Bardfeld, and his son (80+) apparently still lives in the area, and I'll mail him a request for info.  Would be neat to hear about his father, if he's interested in talking about it.  Reaching out to collectors on a QSL card hunt.

Any info or pointers are appreciated!

How would a ham have known this product was available back then?  I checked advertisements monthly for a 10yr period in QST and handbooks and came up blank.  Perhaps he owned an RME 69 and saw it in an RME bulletin?
73
jeffrey





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KA0HCP
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« Reply #1 on: September 07, 2019, 03:43:08 PM »

 I don't have anything to add. I think it was pretty well hashed out on The Zed. Good luck in your search.

I think this was either an RME custom job, or is a frankenstein of various parts and not a RME product.
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New callsign KA0HCP, ex-KB4QAA.  Relocated to Kansas in April 2019.
KD2AZI
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« Reply #2 on: September 08, 2019, 12:14:01 PM »

Thanks, just trying to cover all the bases, may be a different crowd here.
I've started to remove the shelves, and it's very well-made  Smiley
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W2PFY
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« Reply #3 on: September 09, 2019, 01:56:49 PM »

Hello Jeffery, Nice going on that old rig! Perhaps some pictures of the back side of the PA and PS would be appreciated by us?  I have a home brew amplifier that uses a pair of T-55 Taylor tubes. I have enough T-55's thanks to a good friend to build a modulator with period correct transformers including the mod transformers and use another set of T-55's to modulate the rig. T-55's seem like fine tubes so you should have a lot of fun with your rig. Perhaps I'll have mine on the air by next summer? Too many project here and not enough time??

I think old buzzard tubes and rigs are a source of great fun! 

73

Terry 
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Patrick J. / KD5OEI
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« Reply #4 on: September 10, 2019, 11:48:32 PM »


It's not in the "transmitters 1930-1980" book.
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« Reply #5 on: September 12, 2019, 04:52:47 PM »


It's not in the "transmitters 1930-1980" book.

Nor in Ryders Perpetual Troubleshooter.
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K1ZJH
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« Reply #6 on: September 13, 2019, 11:50:16 AM »

Looks to be single channel for commercial.  Nice find.
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Steve - K4HX
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« Reply #7 on: September 13, 2019, 10:33:17 PM »

If it's like most old buzzard transmitters, the circuitry will be fairly simple. You should be able to reverse engineer it.
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« Reply #8 on: September 27, 2019, 01:47:28 AM »

Much bigger things than that have been reverse engineered. It's a pleasant activity really. Plus you get the old radio smell all the time you work.
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Steve W8TOW
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« Reply #9 on: September 29, 2019, 10:43:38 PM »

This was an actual RME transmitter.  Congrats. Probable used Decker coils but B&W will do.....
73 Steve w8tow
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Always buiilding & fixing stuff. Current station is a "Old Buzzard" KW, running a pair of Taylor T-200's modulated by Taylor 203Z's; Johnson 500 / SX-101A; Globe King 400B / BC-1004; and Finally, BC-610 with SX28  CU 160m morn & 75m wkends.
73  W8TOW
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« Reply #10 on: November 06, 2022, 12:25:58 PM »

Since the Subject line is the same, I'm going to resurrect this thread. Some friends of mine are benefactors of an estate that yielded a RME transmitter. I firmly believe it was an Air Force MARS transmitter with the MARS call sign of AF9ALU and I think the ham call sign is W9ANQ. Neither one can I find in the FCC ULS. That not withstanding, I remember seeing one of these at Howard Mills' house. I thought it used a pair of 250T(?)s modulated by a pair of the same. If anyone has any info I would appreciate it.


* RME.jpeg (464.22 KB, 1500x1500 - viewed 83 times.)
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Mike(y)/W3SLK
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WB6NVH
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« Reply #11 on: November 06, 2022, 08:30:00 PM »

Did you try researching the callsign in the old callbooks that are on places like Archive.org?  Things drop out of the ULS rather quickly it seems. That is what I usually do.  So often the previous owner/user seems to be gone without a trace.
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Geoff Fors
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« Reply #12 on: November 07, 2022, 10:27:33 AM »

WB6NVH said:
Quote
Did you try researching the callsign in the old callbooks that are on places like Archive.org?  Things drop out of the ULS rather quickly it seems. That is what I usually do.  So often the previous owner/user seems to be gone without a trace.
Thanks for the suggestion!
132 Signal Battalion Co. B
311 Walton Ave.
Waukesha, WI

EDIT: Which is now the home of the Wisconsin National Guard.

That tells me where its been but I would like to know more about it.

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Mike(y)/W3SLK
Invisible airwaves crackle with life, bright antenna bristle with the energy. Emotional feedback, on timeless wavelength, bearing a gift beyond lights, almost free.... Spirit of Radio/Rush
KD2AZI
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« Reply #13 on: November 07, 2022, 06:32:00 PM »

I'm excited that you found two RME units similar to mine.  Mine has a W3IBI call sign prominently displayed on it, and through local research found a nephew of the Dr. that owned it originally, and he couldn't tell me anything about the guy.

Some friends of mine are benefactors of an estate that yielded a RME transmitter.

Any chance the estate yielded any technical data on these units pictured?
Have you reached out to Howard Mills?  I have a contact in the PA area who thinks he has a big RME transmitter in a shed; I'll track that one down and if anything comes of it I'll post here.
73
Jeffrey
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WB6NVH
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« Reply #14 on: November 07, 2022, 07:38:08 PM »

As suggested above, my suspicion is that these transmitters were originally commercial market transmitters for services such as police and aviation.  Hence the controls all being behind doors.  Police transmitters were mainly on the 1.7 and 2.4 MHz ranges until after the war, where there was a major switch to VHF and FM.  Around 1950-55, the old police transmitters were being placed at the curb and hams often acquired them.  When they were new, the manufacturers advertised them in magazines such as The American City or the APCO Bulletin, so hams would not have seen these ads unless they worked in commercial communications. Airlines and big concerns such as United Fruit would send RFP's to well known manufacturers and get quotes to have what they wanted, made for them.  Today documentation is mostly done by reverse engineering, unfortunately.

These commercial transmitters are often mysteries.  I would like to know how my 1951 era German Rohde & Schwarz HF 750W AM transmitter wound up at the curb on garbage day some 30 years ago in a rural central California area, for example, with a Dymo label tape callsign of an SK ham on it who was already gone without a trace.
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Geoff Fors
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« Reply #15 on: November 07, 2022, 10:21:07 PM »

KD2AZI said:
Quote
Any chance the estate yielded any technical data on these units pictured?
Have you reached out to Howard Mills?  I have a contact in the PA area who thinks he has a big RME transmitter in a shed; I'll track that one down and if anything comes of it I'll post here.
I haven't talked to Howard, W3HM about them. It was about 20~25 years ago that he had the transmitter. I suspect your contact in PA is referring to the same one. However, they just got notified about the estate last week. I'm pretty sure they are 250T's X 250T's
WB6NVH said:
Quote
As suggested above, my suspicion is that these transmitters were originally commercial market transmitters for services such as police and aviation.  Hence the controls all being behind doors.  Police transmitters were mainly on the 1.7 and 2.4 MHz ranges until after the war, where there was a major switch to VHF and FM.  Around 1950-55, the old police transmitters were being placed at the curb and hams often acquired them.  When they were new, the manufacturers advertised them in magazines such as The American City or the APCO Bulletin, so hams would not have seen these ads unless they worked in commercial communications. Airlines and big concerns such as United Fruit would send RFP's to well known manufacturers and get quotes to have what they wanted, made for them.  Today documentation is mostly done by reverse engineering, unfortunately.
I have a Collins 32RA that was used for that and for newspaper dispatching. This RME is a little overkill for a PD. My RCA ET-4336F was used for that service and that was a power house for them.
I think these were a Gov/Mil contract made by RME. I haven't seen a hint of them posted on the internet. Using 250T's makes it somewhere from WWII forward. That's based on the fact the BC-610 used them. However since these came from AF-Mars station it may have been something as a result of the 'nuclear arms race' or CD use because of the power out. That is what makes this so interesting.
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Mike(y)/W3SLK
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w8khk
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« Reply #16 on: November 07, 2022, 10:34:25 PM »


I think these were a Gov/Mil contract made by RME. I haven't seen a hint of them posted on the internet. Using 250T's makes it somewhere from WWII forward. That's based on the fact the BC-610 used them.
It is possible they were made post WWII, but if we assume that based upon the complement of Eimac 250Ts, it could very well be an earlier timeframe.  I say this because the transmitter my grandfather (W8YNG) purchased (in used condition) in 1937 (which I recently restored and am currently operating) employs a pair of Eimac 250-TH finals, modulated by a pair of 810 triodes.  It previously employed a 100-TH RF driver stage, but that is long gone.  It would be interesting to look back through the QST and other advertisements to see when the 250T first appeared. My RME-69 receiver, purchased new by my grandfather, in 1936, is still going strong.  RME offered many various receiver models later, but I am not aware of any other transmitters by RME.
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Rick / W8KHK  ex WB2HKX, WB4GNR
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KD2AZI
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« Reply #17 on: November 07, 2022, 10:44:27 PM »

I'd like to see some close-ups with the doors open when you can - curious to see if you have labeled plug-in units. Mine has a different set of plug-ins for each of the ham bands, and they are labeled as such.
(Geoff - we covered this on AntiqueRadios when I posted there Smiley

The other mystery on my unit is How do I plug a mic in, PTT switch, etc.?  There is no facility for that, only an octal socket in the back, so I'm wondering if there is some other component I'm missing.
There must have been a frequency calibration chart that came with it, as the dials are 0-100 scale.
The final is a T-55, FYI.

This winter I'll start to reverse engineer.  The construction is modular, each of the three chassis is connected by a bespoke connector, allows for good maintenance and may complicate reverse-engineering. 

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