With all the chatting about Deep Voice and other CC stuff I thought "I'm gonna tune my Realistic DX-302 into the VLF band and see what I can hear."
WTH, it's KDX Worldround Radio at 242 kHz. Wait a minute, I left the radio on in the garage. It's my Plug'n Talk intercom rebroadcasting KDX.
A friend gave me the intercoms because they didn't work anymore. A little tweaking and cleaning and hey, they do work.
My tweaking moved the frequency from the model "B" frequency of 160 kHz up to 242 kHz.
The short story is I can pick it up on my DX-302.
Wow, makes those intercoms seem even more interesting as possible short-cuts onto the LW CC spectrum.
Hope you keep it on the air!
242 kHz CC!
Wow!
How well do you get the transmission
on your DX-302? Is it really strong?
Is the transmission FM? Do you have
to slope detect the signal to get audio?
OH YEAH!
I'm starting to build another CC coupler
for my AM LPB CC transmitter.
Best Wishes,
Bruce, DRS2
Still waiting for the parts to arrive for converting the LPB transmitter to the final frequency of 670kHz.
After a whole weekend at 570kHz, Monday went by back on 670kHz, at 1/2-Watt!
In late afternoon I drove up the street and the 1/2-Watt signal got very flappy and fluttery, so the lower end of the Wattage range is very sensitive for this particular system. I came home with a bag of potato chips and boosted back to 2-Watts.
Life can only be complete with intentional radiation and carrier current.
The S meter was about mid scale. Slope detecting helped a little but apparently there is enough AM component to these FM intercoms that dead on was still clear enough.
I'm using a long wire antenna with a homebrew antenna tuner.
That is really really cool!
Bruce, DRS2
Another week has passed waiting for parts to upgrade the LPB transmitter for 970kHz mid-band.
A mysterious e-mail arrived from Mouser, the part supplier, titled : Order Status Update
But the e-mail was a blank page with no message. It contained two attachments that had no apparent use: a GIF picture of the Mouser Logo, and a JPG picture of a Mouser Webpage where status updates are found. But of course a JPG picture is not a webpage.
When I visited the actual Mouser site my order was simply noted as "pending." I sort of already knew that.
So this afternoon I returned to 670kHz temporary frequency, 2Watts, because life without carrier current is a poor excuse.
Doggradio 2 is working on his coupler, which will be very interesting to follow.
Is MRAM still happening at 242kHz?
On the upcoming date of June 4 it will be 1-month since ordering the capacitors needed to build a proper low pass filter to convert the LPB2-20 carrier to 970kHz, AM Midband. In this interim period we tried various ways of wedging into the Lowband.
On one weekend we appeared on 570kHz, with only one guard-band on either side, and local stations nearby at 550 and 590. This was not comfortable, because the lower quality radios are inclined to blend nearby stations together, offering reduced selectivity.
So back to 670kHz, with plenty of open space on the low side, but only one guard band at 680, then a neighbor at 690, with 1kW daytime. So we waited until the sun was behind the trees, turned on 670kHz at 2-Watts, and the 690 neighboring station dropped to 16-Watts nighttime power, and somewhat vanished. In other words, we became a nighttime station, quite unusual if not unheard of.
But this weekend we reviewed a very interesting project done on our behalf by RFB, working in his research laboratory in Wyoming. He ran one of his LPB Lowband transmitters at 970kHz, 2-Watts, over a prolonged period, and determined that this could be done so long as the power was not increased. Having the Lowband filter running at Midband puts extra stress on the transmitter, but he proved it could be done safely.
So we are at 970kHz, 1-Watt, playing it safe but marking our territory.
It really is!
Bruce, DRS2
"So we are at 970kHz, 1-Watt, playing it safe but marking our territory."
Scan for harmonics and intermod spurs and their intensity with a scanner or HF receiver.
Hopefully those caps will arrive soon so you can make the change permanently and with the correct filtering.
RFB
On the 1-month anniversary next Monday I will telephone Mouser and ask if they are still in business. Those caps have still not arrived.
But everyday 1-Watt crippled radio station KDX CC appears at 970kHz, with a spurious buzz at 930kHz, right next to a locally licensed 920kHz.
Today the auto went east, the direction of the powerline and neutral line from this transmitting station, and coverage was very steady, only slightly down after 2.5 blocks. Probably pumping another half Watt would help. Maybe tomorrow.
I love the fact there are so many households in ignorance of the station right there on their dial, if they weren't so busy texting, cell phoning, watching cable and Face Lifting. Or, what is that site? Face Box. No. Face Book? I am not sure.
The more people who ignore my station the better.
Well, hell, my streaming station is ignored by 7-billion people, the entire world population! Try to match that!
What are they doing at Mouser? They aren't sending the caps ordered 1-month and 1-day ago.
Maybe tomorrow I'll crank up the enthusiasm to call and track and find out.
Meanwhile, 970kHz keeps going at 1-Watt with a mis-matched low pass filter.
Perhaps it's time to find another source. 1 month is WAY too long to be waiting for caps..from ANY vendor.
I once ordered no longer available here in the US, some IC chips out of China, and they got here in less than 4 days.
And they were the military grade counterpart IC's to boot!
RFB
should run 1 watt all day long into mismatched lpf's. not quite sure what that would do for harmonic content though. rfb could probably better answer that.
Should run ok at the low power level. However since the LPF is configured for the low portion of the MW band, Carl's TX is operating as if there was no LPF inline at all. The current LPF is merely providing a match to the output pair and to the output connector, but not providing any filtering as it would if the LPF were configured for the mid portion of the MW band.
At higher levels, the configuration of that current LPF will cause the TX linear to self oscillate, and is why Carl experienced that when attempting to go above that 1 watt or so level.
Going higher in frequency power required will be a lot less anyway.
RFB