Marin ditter 4096.85 KHz

[Teotwaki]

Hearing a weak signal on the Kiwi SDR omni right now. 

[Teotwaki]

Same weak strength for today but since I could never hear it at home on my own antennas it's cool to have the kiwi SDR available.

[Teotwaki]

Coming in fair on the KFS Kiwi SDR Omni

[syfr]

Didn't use Radio Shack caps on this one, evidently! :-)

[Teotwaki]

Didn't use Radio Shack caps on this one, evidently! :-)

I sort of recall that this ditter might be on commercial power too but I could be misremembering....   

[syfr]

I think Steve mentioned that as well.

[Teotwaki]

I think Steve mentioned that as well.

Pretty sure he was my source....  one of those long rambling posts somewhere here on the forum that are too much trouble to go back and read through. But it does bring up an interesting concept for people in areas with more clouds than sun. Befriend a person out in the country where you could set up a longwire antenna and also plug into an AC outlet for powering a beacon.

[MojaveBeaconeer]

No ‘long rambling reply here’ save for some clarifications, and I tend to now rarely check-in here, but the MarinDit unit was built in Jan-1988 and is a 3X 2N2222A and 1X 555 beacon in a small blue plastic box - ALL parts were bought at the local RadioShack in Marin back then.  First placed in a deep-canyon in-middle Marin on a gel-cell (I had it out of state in OR going from a rental house for a spell in 1996/7), then put in theMarin-attic in 1999 and strongly heard in Alberta August 2000/Saskatchewan in 2001.  About 2002, the final amp. died and it is only doing its signal from the colpits oscillator transistor (2N2222A) keyed by a 555/2N222A keying transistor circuited to "dit."

It is indeed on house power via a 9v wall-wart.  A tiny enamel wire (end-fed) maybe 50 feet long winds amongst the attic-rafters.  Est. power is less than 5 mW on fund. and it's second harmonic as most know whom monitor it (here it is now daily 8193.77 or so - some drift due to temps.) is easier to catch, generally.

This was the original 4096 cluster beacon.  The second xmtr became the "Hexie" 4096.23 dasher in JTNP, now long gone...

So that is the story and info. re. MarinDit.

73-McGreevy

[DYGradio]

Second harmonic of the ditter fading in and out here on 8194.59 on the horizontal long wire, no copy on the vertical. No joy on the fundamental at 4 MHz. 18:15 UTC 06 FEB 2021

[MojaveBeaconeer]

DGG...,

I have never had the MarinDit beacon that high in frequency - it might drift 20 Hz plus/minus from nominal frequency of 8193.75 kHz due to the "cold to hot temps" in the attic there, but not so high as 8194.59 kHz! 

THAT would be 4097.29 kHz or so (if it is a second harmonic of one of the many beacons I am now hearing here between 4096.2 and 4097.3 kHz)! 

MarinDit "dits" about 88-89 per minute.  I DO hear a slow-dasher and a fast dasher on about 4097.3 +/- since listening the past 3 days...

It is not MarinDit if it is a fast-dasher, as I capture here, BTW.  73

[Teotwaki]

No ‘long rambling reply here’ save for some clarifications, and----SNIP

Good technical summary. Cheap 4096 crystals for ICs are often 20 pF load, 30 ohm resistance for operating series resonance across a gate or inverter to form the oscillator. Since the Marin ditter is a Colpitts operating a little above 4096 MHz I'm wondering what type of crystal was used or what it was pulled out of.

If the antenna was about 50' and end fed it's no wonder the second harmonic is strong since the antenna is roughly a quarter wave at 4 MHz; seriously off resonance for 4096 but not bad for 8 MHz

[DYGradio]

DGG...,

I have never had the MarinDit beacon that high in frequency - it might drift 20 Hz plus/minus from nominal frequency of 8193.75 kHz due to the "cold to hot temps" in the attic there, but not so high as 8194.59 kHz! 

THAT would be 4097.29 kHz or so (if it is a second harmonic of one of the many beacons I am now hearing here between 4096.2 and 4097.3 kHz)! 

MarinDit "dits" about 88-89 per minute.  I DO hear a slow-dasher and a fast dasher on about 4097.3 +/- since listening the past 3 days...

It is not MarinDit if it is a fast-dasher, as I capture here, BTW.  73

Thanks Steve, sounds like I got fooled for sure! I have logged most of the "desert beacons", Colorado, and others over the years but never the MarinDit so got a little over rambunctious. Manty of my loggings were out camping "getting outta town" for the low noise floor and a couple of years ago I moved to a rural area where I now have that low noise floor and real antennas here at home. I do miss the three beacons that used to sing their harmonies around 4096, it was always a peaceful escape to hear all three singing through he night with a nice campfire blazing.

73 and thanks for the clarification, I will keep looking for the real MarinDit.