- April 30, 2019 at 12:56 pm #111016radio8zSenior Moderator
Total posts : 241
For some of us this will be a nostalgic look back to the days of yesteryear, for others this can be informative about radio technology. There is a youtube site titled Mr. Carlson’s Lab where he just posted a rather long look inside the KnightKit AM Broadcaster. It is long because he includes a lot of background information which could be of interest here.
Since I don’t trust the linking on this site, just do a goo goo search for Mr. Carlson’s Lab and you should see it. His site has many other vids which should be of interest to those practicing electronics/radio arts and tech.
NeilApril 30, 2019 at 9:12 pm #111018
I had one of those as a kid. It really put out a signal. We overdrove the audio input but it still sounded better than I expected. It gave my loser friends and me the perfect opportunity to make fools of ourselves all over town. I must say we took full advantage of the situation.
I suppose at this point I don’t know if our antenna was legal or not in its day. I don’t think the rules said anything about a ground wire in those days and I had it mounted in my attic just a couple of feet from the antenna connection outside the window. My antenna was this CB ground plane with drooping radials. The auto parts stores in those days sold loading coils for car antennas to improve reception. I put one on the antenna and it seemed to make a difference.
I hope everyone who had one of these transmitters had a much fun as we did…May 1, 2019 at 7:23 am #111019timinboveyParticipant
Total posts : 671
I still have mine! Still works fine. i think I wrote about if here a few years ago.
I love this guy’s videos!
And there’s an outfit selling reproductions of this transmitter kit on eBay. They’re $119 + shipping.
Might be fun to put another one together 50 years after I built my first one!
TIBMay 1, 2019 at 11:07 am #111020
Thanks, TIB, for the information. I might get one of those. My original seemed to work better than any Part 15 transmitter I’ve had since although I hope the anticipated Rangemaster changes my mind about that…
W9LWAMay 1, 2019 at 3:04 pm #111027ArtisanRadioParticipant
Total posts : 516
I guess it all depends on what you mean by “works better”.
If you’re looking for the best range, then you have to look at field strength, and there’s evidence that in identical conditions, of all the current crop of transmitters, the Rangemaster is tops. There was some question about the AMT5000, but since it’s no longer in production, the issue is moot.
If you’re looking for sound quality, that’s different again, and somewhat subjective.
But even if you take range as the be all and end all, I have to say that there are other factors determining range that can dwarf field strength. Ground conductivity is huge, as well as what kind of ground you can install in your location. Topography, obstructions, background noise levels, interference, even weather, all can play a significant role in range. It’s why people using identical transmitters in different locations with different installation parameters can get vastly different ranges – everything from well under 1/4 mile to over a mile.
I wonder what the field strength of those Knight Kits would be in a transmitter test? I also wonder whether the ranges remembered from using those transmitters come more from the reduced background noise levels in those times (and maybe a not so strict compliance with Part 15).May 1, 2019 at 4:08 pm #111030radio8zSenior Moderator
Total posts : 241
I also built one of these circa 1959 and still have it and it still works. Out of curiosity, a few years ago I measured the DC power input to the “final” stage (the oscillator) and if memory serves it was about 180 mW.
My original installation had the transmitter mounted on a shelf about a foot below the basement ceiling with the antenna wire running up one foot and horizontal for nine feet. There was no intentional ground but I suspect the power line and the audio feed from my bedroom “studio” upstairs served this function. I knew nothing about coil loading antennas and wonder what effect such loading would have had, though I am not interested enough to experiment now to find out.
None of our family cars had radios so the only range checks I made were bicycle mobile with my Motorola transistorized portable and checks with neighbors. The AM noise floor was greatly lower then compared to now and neighbors could hear the station up to a quarter of a mile away. My portable could hear it at about the same distance with a good signal.
Countless hours were spent by me with my high school buddies playing with this thing. To this day I find it hard to believe that I never received an electrical shock from it. I used it for a short time in college but academic demands forced QRT for many years until I found time to occasionally fire it up again just for the fun of doing so.
NeilMay 2, 2019 at 8:31 am #111036
I’m not surprised to hear it was a bit overpowered. My dad would take me out now and then in the blue ’67 Mercury station wagon and we still had a pretty good signal for a couple of miles. I also had a similar transmitter from Lafayette that never worked nearly as well, but it probably wasn’t giving me 180 millawatts instead of 100, either. Ignorance was bliss about a lot of things back then.
One day I thought it would be a good idea to write the FCC and ask how legal it would be to somehow put a transmitter up on a tower and feed it from a studio in the house kind of like Rangemasters do now. As I recall, they said it might violate the rules and they were keeping my inquiry on file. I thought that was quite an honor. My parents suspected differently…May 4, 2019 at 8:28 am #111050BrooceParticipant
Total posts : 49
<p style=”text-align: left;”><b>Really fun thread!</b></p>
I missed the experience of the
Our bunch have a parallel story.
We had the Lafayette KT-195 transmitter kit. (Two of them,
actually.) We also had 2 Lafayette
990177 phono oscillators that used 12BE6 and 35W4 tubes.
They were all bad performers
and were very dangerous if not
operated in a very very careful way.
The rest of our story is very much the same.
Transistor portable radios were
attached to bicycles.
There were all sorts of antennas and experiments with ground connections. There were long audio cables going back to our
first “studios” with almost broken record players, and silly looking microphones that were
part of unused intercom systems. And there was one
tape recorder with a motor that
made scraping sounds when it was running.
It was one of the best times of my life.
1969. Oh my.
Brooce, Hartford CTMay 6, 2019 at 2:58 am #111058BrooceParticipant
Total posts : 49
I just watched the video Neil mentioned about the KnightKit transmitter.
It was GREAT.
BrooceMay 7, 2019 at 11:32 am #111066RichPowersParticipant
Total posts : 421
I’ve probably mentioned this before, but here’s a cool story about the Knight transmitter from 1957:
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