Carl Allan Poe.. your wit is endless
I got curious.. Here's you're mic Bruce, the seller says he found it in the swamp tied to a kite...
$29.99 or best offer (kite not included)
http://cgi.ebay.com/REALISTIC-APOLLO-FM-90-WIRELESS-MICROPHONE-WORKS-GREAT-/150526493136?pt=LH_DefaultDomain_0&hash=item230c1401d0&x=45&y=8
And here's a P-Box memory lane page..
http://my.core.com/~sparktron/pbox.html
I put the FM-90 transmitter up
on a kite to see how far the signal would go.
Did that once...but all kites even with a good tail for balance, flies unstable tied to a stationary anchor.
So I decided to do the "Mini-Hindenburg" method. With a few large party balloons and cheap readily available helium, an Easter basket, and fishing line, I made what I called a "Insta-Tower" to hoist that FM or AM up as high as I needed it to go.
Put my Panaxis AM 100 in it with a long #24 insulated wire strung down the center fishing line. That little 100 covered the entire town on that mere 100mW. The FM version, using the Panaxis FM 2-20 not only covered the entire town, but about 3 miles outside of it as well. Although both required +/- 15v...they did not require a lot of current and using the available solar cells at that time made things easy to over come running power up to them. Both got their audio from scrapped Ch 14 toy CB hand helds that were also powered by the array of solar cells.
The "Insta-Tower" is only limited in how far up it can go by the length of fishing line you use in the center and guy points. My first attempt rose that AM-100 up into the air 60 feet. Then later experiments took both the FM and AM units at the same time to 150 feet.
At that time I was living in an area where the winds rarely blew over 5-10 mph. Very stable and quite cheap to make, and does the job well for both AM and FM.
Back then...mid 70's or so, and in the little town I was in, no one was too highly concerned about throwing up an AM stick or wire longer than 3 meters. Ran my little stations that way for about 2 years then I moved. Never have repeated that "Insta-Tower" method since...but for good reason where I am at now. They do not call my location "Windy Wyoming" for nothing! 😀
But just for kicks and grins I may do that again even with our 40+ mph winds sporting gusts as strong as 60mph at times....See how good the Easter basket will hold up in a light breeze!
RFB
That's the coolest, most unique part15 story I ever heard
Thanks. Can't remember if it was the mid to late 70's...may have been the early 80's. I was doing a lot of hobby stuff back then..of course back then hobbies, even Ham stuff was more affordable than it is today.
I was just sitting there one day and was reading an old magazine that had an article about the Hindenburg. The idea light came on brightly and off to the races I go! 😀
RFB
I would just replace
that limited 6 MHz/divide = f with a crystal
oscillator running at whatever channel I wanted.
One way would be to use the exact circuit used in the solid state LPB exciters, which uses the MC12061P oscillator and SN7492 divide by 6 IC that does not have the 6Mhz limit.
For example, my AM station operates on 1670. If I were using the LPB exciter, I would use a 10.020Mhz crystal. 10.020Mhz / 6 = 1.670.
Woops! Corrected divide by # number! 😀
RFB
By the way, I just looked and 6AL11s
(NOS) for the LPB unit seem to be
pretty inexpensive.
Additionally, the is a guy on the net,
whose callsign is AF4K. He sells all
kinds of neat stuff. I notice he has
many crystals for the AM BCB that
are in FT-243 holders. I have some
AM channels that are empty during
the day that he has crystals for.
For instance, he has 1020 kHz, 1330 kHz,
and 1460 kHz. RFB, do you have any
comments on that?
Crystals on the low end of the band are
much harder to find. There is a place
that makes them for about $80, but
that would be a last resort. 620 kHz,
550 kHz, and 750 kHz are very quiet
here during the day. Especially 550.
So, anyway, let me know what you think.
Best Wishes,
Bruce, MICRO1690/1700
For instance, he has 1020 kHz, 1330 kHz,
and 1460 kHz. RFB, do you have any
comments on that?
I am not sure exactly what you mean by having comments on those frequencies and/or crystals, but having as many to work with will obviously give you more firepower to work with, that is finding a spot on the dial to call home.
Out here in Wyoming, the dial is quite empty during the day. There are 3 licensed stations here, 830, 1030 and 1400. There is a 4th, but I know the ownership, since I contract engineer for his 12 stations, 5 of which are located in Casper, 1230 KVOC went dark on Dec. 31st 2010 due to the owner not renewing the ESPN contract. He has yet to do anything about it...and a few other things I keep advising him to do.
At night the dial has a few more stations, mostly the clear channel flame throwers and maybe a couple 5Kw's in a couple of towns in Wy. itself. Still there is plenty of room to play in.
By the way, I just looked and 6AL11s
(NOS) for the LPB unit seem to be
pretty inexpensive.
Usually are. However if you want new tubes there are plenty of vendors for those as well on the net. Believe it or not, but Russia still has a few tube manufacturers churning out those old valves. And despite the old way of thinking, Russia tube manufacturers make excellent quality tubes. If they did not, companies like Peavey, Yamaha and others would not have them in their PA and instrument power amplifiers.
Yes Brian is a great guy to work with (af4k) and he makes incredibly good crystals. I have bought several from him and I highly recommend him and his crystals.
http://www.af4k.com/crystals.htm
He currently has crystals for 1700 in the HC6/U case for a mere 16 bucks! These will work also in your LPB unit as well as the later solid state LPB's
However he does have the FT243 case style which is the original case style for the LPB 6 series units. And he has a line of them that go from 100Khz to 1.5Mhz and 1.5Mhz to 1.999Mhz...which right there gives you crystals for the entire AM band!!
100Khz to 1.5Mhz
http://www.af4k.com/FT243crystals100-1499khz.htm
1.5Mhz to 1.999Mhz
http://www.af4k.com/FT243crystals1500-1999khz.htm
Since you already found his site, talk to him. Dont know why I didn't notice that but your on the right track!!! 😀
RFB
Hey Micro...there is a 600Khz crystal for sale on ebay..60 bucks.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=180634794155&ssPageName=ADME:B:SS:US:1123
Not exactly the frequency your looking for..but may be useful.
RFB
Thank you so much for all of the
information about the crystals.
600 kHz is taken here, unfortunately.
If I knew how to grind crystals, I could
move it up to 620, which is empty.
HA! There's no way that's ever going to
happen!
I has been a lot of fun talking to you.
My projects go slowly, but I will keep
you informed of any interesting stuff
that comes along.
Best Wishes,
Bruce, MICRO1690/1700
Have you considered a PLL circuit in front of that oscillator section? You can replace that crystal section of the oscillator circuit with an LC circuit controlled by a PLL loop and totally eliminate the need for a crystal.
Using what is known as "equivalent" resonant LC tank to replace a crystal and having that LC tank controlled through a varactor diode with a PLL circuit, you can solve the problem of the crystal issue, as well as give your transmitter the ability to operate on various frequencies easily.
All you need to do is make the LC tank circuit so that it makes the oscillator tube oscillate properly, and then the PLL circuit loop can sample that oscillator output through some attenuation back into the PLL to maintain proper frequency lock. Building an LC tank circuit equivalent is pretty easy and adding a PLL loop by use of readily available PLL kits is also easy to incorporate into the overall modification.
Since you are only replacing the crystal portion of the circuit and not changing out the entire oscillator section, the modification would not take the transmitter radically outside of the design parameters and outside of its intended mode of operation..in this case Part 15.221 Carrier Current. Your simply replacing the crystal element with an LC circuit controlled by PLL instead of a tuned inductor, which a tuned inductor will drift due to temperature changes etc. Thus your ensuring the thing operates ON FREQUENCY as it would with a crystal.
RFB