Lafayette (sp?) Part 15 Transmitter

I think the name "Lafayette" also operated at various times as "Allied Radio Corp" and called their products "Knight Kits."

I have saved the product lit on 3-models. The oldest version I had was Knight Model 760 Wireless Phono Oscillator, Product # 38K162, which used larger sized tubes, 50L6GT and 35Z5GT.

The next release used smaller tubes 12AX7, 50B5 & 35W4. This was Prod.# 38K051

The last version I had was # 83Y706 which used 12Ax7, and two 50C5s.

The last two models had a volume control that controlled the mic or line audio, only one of which could be used at a time.

Yours was probably part of this same family.

I don't recall that Lafayette Radio offered such a transmitter. Could it have been a Graymark housebranded?

http://www.smecc.org/graymark_transmiter.htm

Here's a link to an article about the Knight Kit just for general information:

http://www.smecc.org/knight_kit_home_broadcasters_-_allied_electronics.htm

Neil

Around '59 or '60 I recall that Allied and Lafayette as competing companies. I recall dad having catalogs from both, along with Radio Shack, Heathkit and Dynaco

It's possible Graymark and Knightkit were kit producers featured in the bigger catalogs, but the Wiki article on Allied stated Knightkit was an Allied house brand.

Here are the web pages I looked at:

http://en.wikipedia.org/wiki/Allied_Radio

http://en.wikipedia.org/wiki/Lafayette_Radio

http://en.wikipedia.org/wiki/Allied_Radio

http://www.nostalgickitscentral.com/

Gronsk, you are entirely correct. There was such a transmitter, and I owned one. I might still have it somewhere at my parents' house, but I actually think that I probably got rid of it.

It was a kit. To be honest, it was a terrible performer. It had very weak modulation. It had very weak RF output, too-- I recall the signal going about 50 feet or so. It was no match for the Knight Wireless Broadcaster, which I also owned (and still have). There was no connection between Lafayette and Allied. They were separate companies.

I recall the bluish-green metal case and the slide switch for the power (it was AC line powered). And the mic jack. I thought that the frequency control was a compression trimmer capacitor. As I recall, it didn't cover the whole band.

I was very disappointed in the performance of this unit and it was fairly quickly relegated to the back of the workbench. The Knight, on the other hand, lives on and still today is pretty impressive...

Next time I am at my folks' house I will look around and see what I can find on it. But I'm not overly optimistic...

Hi Guys!
I have read this website for a couple of years
(slowly, because I am legally blind.) I have
an SS-Tran for yardcasting but it is not on
right now.
I have enjoyed the wealth of knowledge and
info about part 15.
I had a Lafayette KT-195 am transmitter in
1968. It had no power transformer so it was
dangerous. It used a 36AM3B and 2 50BM8
tubes. It was "AC-DC." It had a speaker
connection in the back, but the audio was way
too loud if you hooked on a speaker when you
were transmitting with "correct?" modulation.
It transmitted a mixture of am and fm, so you
had to sort-of slope detect the audio when were
trying to tune it in. When my best friend and
I built it, we made many mistakes. When my father
finally fixed it, we found that it was really transmitting
in the "marine band" at about 2.1 MHz.
The case was blue and grey, it had a slide switch in
the front along with the frequency adjust trimmer
that stuck out of the front panel. There was lots
of hum on the signal.
We also had another Lafayette transmitter, or
phono oscillator, as it was called. It was an open
chassis unit that had no power switch. It was
silver metallic in color. It used a 35W4 rectifier
and a 12BE6 that did all the real RF and audio
stuff. The tube heaters were series connected
through a gigantic wire wound resistor that ran
real hot. A ten foot green wire protruded out
the back. It was also AC-DC and very dangerous.
Having had very little luck with these units, the
part15 crowd in my neighborhood went to FM,
with a Radio Shack P-Box kit. The RF oscillator
in that was a 2N5223. If you google Radio Shack
P-Box, you might find a website about those kits,
because there used to be one out there.
All the above was in 1968. The Radio Shack kit
started getting used all over the country by kids
like us. It was too powerful and Radio Shack
removed it from the kit line.
I use my SS-Tran to transmit around the house.
Since I am legally blind, everything takes a long
time to do. Maybe someday I will build the
outside 3 meter antenna, but it is not on the
agenda right now. When it was on, it was on
1700 kHz. It was little operation, not a serious
part15 am station. My kids got a real kick out
of it. My wife didn't think too much of it.
Radio has always been part of me and I have
loved reading this website. But you won't hear
too much from me, because my vision is very
lacking.
Thanks a lot for such a great website!
MICRO1700

MICRO1700,

Welcome aboard! You apparently have nailed the perfect response to gronsk's question with your recount of the Lafayette unit.

Glad that after all this time reading here you decided to sign up and post. Please don't be a stranger. I bet you have stories to tell from the good old days and the present good days.

Neil

Hi Neil!
I hope you get this. I can only see out of part of one eye
so I hope I'm doing this right. If not, I will try again
another way.
I do have some pretty funny stories about what we
didn't know and how we almost blew ourselves up
a few times with the "no transformer AC/DC stuff.
I have really enjoyed your comments over the years.
I love the SS-Tran. I guess I've had it for about 3
years. I built it when my vision was better. (I've
had eye issues all my life, so to me it's no big deal.)
The reason I refer to myself as noise and static radio
is because I am an AM broadcast band DXer.
Anyway, I just thought of a few more things Gronsk
and others might remember.
The KT-195 came in 2 versions. There was the kit
for about $17.95 (1968 dollars.) Then there was
the built version for something like $24.95.
We got the kit. What a mess! My best friend was
better at making strange sculptures with piles of
solder than joining together electronic parts.
I remember the instruction manual specified that
the transmitter not be used on a metal table!
Yikes!
The other phono oscillator from Lafayette was not
a kit and it only cost about six dollars. I could see
why. There was nothing in it. But to me,
transmitting 50 feet with a drifty FMing oscillator
was like going to heaven. Holding this thing in
my hand (when it was unplugged) was like
holding a piece of gold! It seemed to put out
on 800 khz and 1600 khz equally when it was
running. Our chosen frequency was 1600. We
knew we couldn't go above that and be legal, so
we tried to transmit there. It didn't seem to
mater to us that there was a 5 KW daytimer on
the channel about 30 miles to the north!
Oh, the model number on the smaller unit was
a Lafayette phono oscillator 990177. We called
it the "nine-nine." It was a disaster too. Boy
we can sure laugh at this now (and I sure do!)
but we were very lucky we didn't get hurt!
Thank so much!

I had a KT-195 Lafayette broadcaster in 1963 when I was about 10 years old. I recently found one on Ebay and got it!

It did not come with a manual but I have hand drawn the schematic from this unit and then rebuilt it.

The descriptions I've read here are fairly accurate with regard to the operating characteristics. And although the circuit has the typical AC/DC floating ground capacitively coupled to the chassis, yes you can get a nasty bite depending upon how it is plugged in.

I have modified the modulation scheme from screen grid modulation to plate modulation and the difference is remarkable, much clearer and louder. I basically disconnected the audio feed from the oscillator screen grid and tied the oscillator plate to the audio output plate adding an rf choke and rf bypass cap to decouple the rf from the audio stage. The "fm'ing" seems none the worse.

Then the tinkering began. Since the original design simply couples the oscillator plate directly to the antenna with a capacitor, I added a PI network to better match the output. Of course this would invalidate the Part 15 design as the output increased nearly ten fold.

When I was 10 years old, it was a bit disappointing that my home made one transistor transmitter out performed this great looking kit. So, naturally I had to see what could be done about that being given a second chance at childhood dreams.

It has taken a place on my "yesterdays" shelf along with a few Remco Caravelles, Cub Scout crystal radios, a Remco Tiny Tim radio and other stuff from those by-gone days.

Don't forget, those were 'suicide transmitters." If you plugged into an icorrectly wired outlet, "pop...zoom, to the moon Alice!" LOL!

John,

Yes, this is true as I learned at age 12 with my Knight Kit. But we are here to reminisce and compare stories. Maybe some are not due to this but we can carry on.

Neil

Yes, even though the AC "floating ground" prevents a direct AC line connection to the chassis, there is enough "leakage" current through the .05 uf capacitor between the "floating ground" and the chassis to give you an uncomfortable zap.

The real killer is the ground on the two RCA audio input jacks. They are insulated from the chassis but tied directly to the "floating ground" which is connected to one side of the AC line. That is the big flaw in the design as connecting the audio cable to a grounded source is a potential AC short circuit when the AC is plugged in backwards. A real hot dogger!

Audio input transformers or better yet, an AC isolation transformer needed here!

If anyone wants a copy of my hand drawn schematic of the KT-195 or pictures of the unit let me know.

Hi Guys!
I had one more thing to say about our adventures with
the Lafayette KT-195, which my 14 year old buddies
and I referred to as "the KT."
But first I want to congratulate MRAM, who found one
whole and in one piece and improved it significantly!
As far as I'm concerned, that's a really big deal!
Anyway, my brilliant 14 year-old-mind had a "great
idea." Why not try to transmit stereo with two transmitters
and receive it on two AM radios!?
I had a beautiful Sony TC-350 Reel to Reel Tape Deck.
I didn't really have much money and this wonderful
tape machine fell into my lap almost by accident.
I took 2 RCA patch cords. I plugged the left channel of the output
of the deck into the line input of the KT-195.
I turned on the KT-195. I turned on the Sony Deck
and started it running. So far so good because I
heard one stereo channel through AM radio number
one. (Even though the main signal of the KT-195
was really transmitting on about 2100 kHz because
we built it wrong) I could still hear
some kind of product or image on the AM band on the
first radio and I could hear the music (the left channel)
on that radio. It sounded OK.
Then I plugged a patch cord from the right channel out
of the Sony deck and into the input of that other
"transmitter," the Lafayette 990177 phono oscillator.
It, too, had no power transformer and was dangerous.
I held the AC plug of the 991077 in my hand and
approached the AC outlet. I started to plug the plug
into the outlet. As I got the plug just into the outlet
a white flash from inside the AC outlet jumped to the
plug! It looked like the inside of the outlet had lit up!
I fell back stunned. Not by an AC shock, though, it
was really a lot more like terror in my 14 year-old mind!
AM radio number two (for the right channel) had been forgotten.
I knew something bad had happened and began
wondering if the beautiful Sony reel to reel deck (which
was the heart of my Part 15 station) was OK! Had it
survived? It was literally in between the two transmitters!
Well... The answer was NO. The motor worked, but
the units audio section was dead. It would not record
or play, and the VU meter needles just sat there and
jittered (sp?) around.
Was my dad mad! He said I had been hooking up good
stereo equipment to junk, which, I guess, was pretty
true.
The Sony reel to reel was eventually repaired (because
my dad was (and still is) a great guy. The local department
store had an electronic repair shop and the techs there
were able to replace a chain of components that had been
destroyed. The deck was saved.
I never tried THAT experiment in broadcasting again. We
just kept trying other things. That bump in the road didn't
stop our Part 15 adventures. I still have the Sony deck.
It sort of still works 41 years later.
I hope this story gets into the right discussion thread.
As I said, my eyes are messed up and I find it hard to
navigate a web site.
But, I HAD to tell that story!
One more little item. I believe the KT-195 was supposed
to operate between 900 and 1600 kHz, which, as I
mentioned, mine never really did.
Thanks a lot guys!

Thank you all so much! I will be going over all these great replies today and maybe I'll find what I'm looking for. Your help is really appreciated!

An old trick I used to use before finding a Variac for my projects was to use two filament transformers wired back to back as an isolation transformer. I.E. go in to one transformer with 110 VAC hook it's 12 VAC (could be any voltage out as long as it matches the voltage of the winding you hook it to in the second transformer) output to the 12 VAC connection of the second transformer and voila... 110 VAC isolated output from the second transformer. Do not exceed either of the current or power ratings of either transformer.