The first FM transmitter I ever saw was an RCA BTF-1C in 1967. Probably made in the 50's...had a pair of 4-125A's driving a 5762. The exciter had a scope built in to allow verification that the multiplier stages were multiplying the correct number of times. To my 14 year old eyes, it was a sight to behold. Does anyone have a picture of one of these? Lot of long dormant memories in that model.
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RCA BTF1C
- Thread starter BobOnTheJob
- Start date
I have yet to post a photo of the full transmitter on the site, but WMMM-FM used a somewhat newer BTF-1D back when first signed on the FM in September, 1962. The birth of WMMM-FM page does show a close-up of the scope that is on the exciter, though.
If I can sift though my reference materials and find the pix of the transmitter I'll post them somewhere.
If I can sift though my reference materials and find the pix of the transmitter I'll post them somewhere.
There were two esciters. The first one had a cap on the polyphase motor for AGC. Later models had a multiturn coil, and were somewhat more stable - relatively speaking. (We had a BTF 3). Option of the day was a PhaseoTron tube in an external coil. Take your pick.
I'd sure love to see a pic of a BTF1C...there are many pics of the RCA AM's from that era but apparently no one thought FM was worthy of even a snapshot!
...forgot to give credit for this link -- It's from a website run by Fred Vobbe, W8HDU in Lima, Ohio.
M
MickeyD
Guest
Bill DeFelice said:I have yet to post a photo of the full transmitter on the site, but WMMM-FM used a somewhat newer BTF-1D back when first signed on the FM in September, 1962. The birth of WMMM-FM page does show a close-up of the scope that is on the exciter, though.
If I can sift though my reference materials and find the pix of the transmitter I'll post them somewhere.
I lived in Fairfield back in the 80's and listened to WMMM a friend of mine used to work there occasionally. I never understood why they sold the FM alone and kept the AM. Regardless of ownership regulations I would have tried to stuff it into the sale and let them get rid of it. It lasted longger then I thought before they threw in the towel and gave it to Sacred Heart U.
Another mystery. Why does Sacred Heart collect old AM stations?
MickeyD said:Bill DeFelice said:I have yet to post a photo of the full transmitter on the site, but WMMM-FM used a somewhat newer BTF-1D back when first signed on the FM in September, 1962. The birth of WMMM-FM page does show a close-up of the scope that is on the exciter, though.
If I can sift though my reference materials and find the pix of the transmitter I'll post them somewhere.
I lived in Fairfield back in the 80's and listened to WMMM a friend of mine used to work there occasionally. I never understood why they sold the FM alone and kept the AM. Regardless of ownership regulations I would have tried to stuff it into the sale and let them get rid of it. It lasted longger then I thought before they threw in the towel and gave it to Sacred Heart U.
Another mystery. Why does Sacred Heart collect old AM stations?
Of course by then WMMM's FM was running a Collins box up at the Wilton transmitter site and when the station was sold the transmitter site was moved to Bridgeport where they're running BE boxes for main and backup. I can't even speculate what motivated Donald Flamm to sell the FM instead of the AM.
Who was your friend who worked at WMMM? I'd like to make sure I have them included in the staff roster on the History of Westport Connecticut Radio - WMMM tribute website.
As far as Sacred Heart collecting old AM radio stations goes I don't know, but it boils me that I can't get a high school campus in the area more than a lowly campus-limited Part 15 signal while Sacred Heart clogs up every AM signal from Stamford to Westport.
I ran across this while searching for the BTF1C...this one is dated 1958 and it looks relatively modern compared to the bigger 1C. Someone in California was using a BTF1C for a 2 meter ham repeater transmitter (with a custom built 146mhz 1 bay antenna no less!) but unfortunately, their pictures did not show the BTF1C. I recall the 5762 PA tube was mounted "upside down" and had filament and grid leads sticking upward. It was a grounded grid rig driven by a pair of 4-125A's. This is all from memory...I haven't seen this since I was 14 years old...many a moon ago.everydayguy said:
BobOnTheJob said:2 meter ham repeater transmitter (with a custom built 146mhz 1 bay antenna no less!) but unfortunately, their pictures did not show the BTF1C. I recall the 5762 PA tube was mounted "upside down" and had filament and grid leads sticking upward. It was a grounded grid rig driven by a pair of 4-125A's. This is all from memory...I haven't seen this since I was 14 years old...many a moon ago.
We had a RCA TT25BL 25kw power amp on our backup (TV) transmitter in Madison. It ran *seven* of these 5762s in parallel -- yes, they were mounted upside-down & with the filament leads sticking out the top. The filament was center-tapped -- the grid was a flange between the filament leads and the plate. (/heat radiator)
w9wi said:BobOnTheJob said:2 meter ham repeater transmitter (with a custom built 146mhz 1 bay antenna no less!) but unfortunately, their pictures did not show the BTF1C. I recall the 5762 PA tube was mounted "upside down" and had filament and grid leads sticking upward. It was a grounded grid rig driven by a pair of 4-125A's. This is all from memory...I haven't seen this since I was 14 years old...many a moon ago.
We had a RCA TT25BL 25kw power amp on our backup (TV) transmitter in Madison. It ran *seven* of these 5762s in parallel -- yes, they were mounted upside-down & with the filament leads sticking out the top. The filament was center-tapped -- the grid was a flange between the filament leads and the plate. (/heat radiator)
We had a 25BH that backed up a 25FH in Albany, GA. It was a pretty cool sight to see that B lit up on occasion. It was replaced by a Larcan and the B was scrapped.
Fondly remembered as the RCA "cluster of seven". Reviews of the famous RCA 5762 indirectly heated cathode triodes were slightly less than stellar.
http://www.fmamradios.com/TT-25AL.html
Best regards,
w/
http://www.fmamradios.com/TT-25AL.html
Best regards,
w/
I'm wondering if you've seen this? It's not an up-close picture, but here's the 1950 RCA Broadcast Catalog. The BTF1C is on page 246:
http://www.americanradiohistory.com...Transmitters-RCA-1950-Broadcast-Catalog-4.pdf
http://www.americanradiohistory.com...Transmitters-RCA-1950-Broadcast-Catalog-4.pdf
Here's a couple more links to check out:
Here's RCA Broadcast News #45, June 1947. Check out page 4 to see THE TRANSMITTER MAN'S TRANSMITTER!!
http://www.americanradiohistory.com/Archive-RCA-Broadcast-News/RCA-BC-55-com.pdf
Scroll to page 50-52 in this RCA Broadcast News #55, June 1949 to see the site of WRAK-FM Williamsport, PA. The transmitter was a BTF-1C into an RCA four-pylon antenna. The station was a class B on 100.3, moved to 102.7 sometime in the 60's. It's now WKSB, "Kiss 102.7," still broadcasting from the same 1948 tower on Skyline Drive on Bald Eagle Mountain.
http://www.americanradiohistory.com/Archive-RCA-Broadcast-News/RCA-BC-55-com.pdf
RCA Broadcast News #48, March 1948: Page 57, a closeup of the transmitter at KFBK FM Sacramento (92.5, the same KFBK-FM that's still on the air today.)
http://www.americanradiohistory.com/Archive-RCA-Broadcast-News/RCA-BC-48-com.pdf
Here's RCA Broadcast News #45, June 1947. Check out page 4 to see THE TRANSMITTER MAN'S TRANSMITTER!!
http://www.americanradiohistory.com/Archive-RCA-Broadcast-News/RCA-BC-55-com.pdf
Scroll to page 50-52 in this RCA Broadcast News #55, June 1949 to see the site of WRAK-FM Williamsport, PA. The transmitter was a BTF-1C into an RCA four-pylon antenna. The station was a class B on 100.3, moved to 102.7 sometime in the 60's. It's now WKSB, "Kiss 102.7," still broadcasting from the same 1948 tower on Skyline Drive on Bald Eagle Mountain.
http://www.americanradiohistory.com/Archive-RCA-Broadcast-News/RCA-BC-55-com.pdf
RCA Broadcast News #48, March 1948: Page 57, a closeup of the transmitter at KFBK FM Sacramento (92.5, the same KFBK-FM that's still on the air today.)
http://www.americanradiohistory.com/Archive-RCA-Broadcast-News/RCA-BC-48-com.pdf
Thanks! Page 59 of the BC-48 link shows the best pic of a BTF1C I've yet seen. I can still picture the GM using the motorized tuning controls to minimize the brightness of the glowing plates of the 4-125A's (the PA was stable but the IPA wandered around from day to day). A friend emailed me a page from an RCA catalog that indicates this model was introduced in 1947...so it could have been 20 years old when I read the meters on it in '67. Again, thanks to all who participated in this thread...the reading of the posted links has been fascinating even where it didn't directly reference the BTF1C. Maybe I was born 20 years too late? Cool stuff...reelyreal said:Here's a couple more links to check out:
Here's RCA Broadcast News #45, June 1947. Check out page 4 to see THE TRANSMITTER MAN'S TRANSMITTER!!
http://www.americanradiohistory.com/Archive-RCA-Broadcast-News/RCA-BC-55-com.pdf
Scroll to page 50-52 in this RCA Broadcast News #55, June 1949 to see the site of WRAK-FM Williamsport, PA. The transmitter was a BTF-1C into an RCA four-pylon antenna. The station was a class B on 100.3, moved to 102.7 sometime in the 60's. It's now WKSB, "Kiss 102.7," still broadcasting from the same 1948 tower on Skyline Drive on Bald Eagle Mountain.
http://www.americanradiohistory.com/Archive-RCA-Broadcast-News/RCA-BC-55-com.pdf
RCA Broadcast News #48, March 1948: Page 57, a closeup of the transmitter at KFBK FM Sacramento (92.5, the same KFBK-FM that's still on the air today.)
http://www.americanradiohistory.com/Archive-RCA-Broadcast-News/RCA-BC-48-com.pdf
Watt Hairston said:Fondly remembered as the RCA "cluster of seven". Reviews of the famous RCA 5762 indirectly heated cathode triodes were slightly less than stellar.
http://www.fmamradios.com/TT-25AL.html
Best regards,
w/
Ours sat in the back room with the dummy load and air conditioning units and for some reason always reminded me of Robby the Robot.
H
hmb
Guest
I Read these posts with great interest since I still have one of these at my Station WQKX-FM).Station went on air in 1948 (WKOK-FM). It was used in conjuction with a RCA Pylon style antenna & 300 ft Blaw Knaux Self supporting tower. The tower still stands and the transmitter is still is operational and believe or not we modified it for Stereo operation back in the 70's for use as a standby to the now Retired RCA 10 Kw. The old girl still gets fired up and if we have a failure with the Harris ZD-16 or the RCA 10KW Analog. We can press it into operation. It is amazing to have all the transmitters operational that we utilized since 1948.TLC goes a long way.
reelyreal said:Here's RCA Broadcast News #45, June 1947. Check out page 4 to see THE TRANSMITTER MAN'S TRANSMITTER!!
Hell yea! That was back when a transmitter could KILL you! Now, they are nothing more than kitchen appliances.
H
hmb
Guest
It was a Electronic & Mechanical Marvel for it's day.I have some great pictures of this Box.
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