Grape Anticipation & Antenna Experiments

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Gary Mikitin

Aug 6, 2022, 4:29:57 PM8/6/22
to hamsci-grape

A question was posed in the August 4th Grape telecon:  What could the general Grape community be doing to advance the project while waiting for the next Grape hardware releases (versions 1.2, 2.0)?

Food for thought:  Antennas!

Many of us have a pretty good idea of which stations and frequencies we can monitor…those which produce reasonably good signals for most of the day.  10 and 15 MHz WWV seem the most popular, while some have settled on reception of CHU.

Dipoles are the go-to solution for many.  20m and 30m dipoles work well for receiving on 15 and 10 MHz respectively, but also consider orientation:  Could you move them (or raise additional antennas) for better reception?   How about shortened, pre-amplified receiving antennas?  There are also miniature loops (3-5 feet in diameter) which exhibit good directivity and noise reduction characteristics.

Speaking of noise:  The lower your noise floor, the more signals you can detect.  If you can locate and mitigate noise sources near your station, you’ll get better Grape reception, and, if you are an active ham, your CW, SSB, FT8, etc. activities will benefit as well.

73 de Gary, AF8A

P.S.  A brief story regarding a ham who shall remain nameless:   Participation in HamSCI has provided beneficial to this ham.  He (or she) lives in an antenna restricted community - their HOA (Home Owners Association) rules, while not banning antennas entirely, have onerous requirements about location, approvals, and so on.  This ham erected a 20m quarter wave vertical in their back yard - a single, slim aluminum pole, just over 16 feet tall, fairly sturdy, tapering from about 1.5 inches at the bottom to 7/8 inches at the top.  It is strong enough to support an anemometer - and thus it is a ‘weather station’, and not at all restricted, or even mentioned, in the HOA rules.  Further, when neighbors ask about it, and what they do with it, the ham tells them “I have some friends at the local university.  I assist their research by collecting atmospheric data”. That ends the conversation every time - no more questions!   (He/she purposely says ‘atmospheric’, not ‘ionospheric’, because how many average Joes or Janes have heard of the ionosphere?). That ham says “Thanks HamSCI, for allowing me to create a cover story for my ‘antennamometer’ “!

P.P.S.  The same HOA rules prohibit ‘digging more than 1 foot below ground’.  That likely puts the kai-bash on a buried magnetometer, sorry to say.


Dr. Nathaniel A. Frissell Ph.D.

Aug 8, 2022, 5:33:00 AM8/8/22
to Gary Mikitin, hamsci-grape

Hi Gary,


Thanks! I absolutely agree with this. Any suggestions on improving the antennas would be very welcome.


Also, thanks for the story about how HamSCI is helping certain ham stay active!


73 Nathaniel W2NAF

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Julius Madey

Aug 8, 2022, 11:51:34 AM8/8/22
Don't give up on the magnetometer.  Temperature stability over a 24 hour period is more important than long term stability ... Suggestion: use a garden augur in a hand drill to go down one foot.  One of maxim's one wire sensors or a 9808 on the i2c bus is a good sensor ... bury the sensor and log the temps for a few days. 

Also, we're talking about a 2 inch diameter hole here, not a major excavation ... the garden augur will easily hit 20 inches, which should be sufficient ....

I've successfully run a 6 inch wall architectural insulating foam box with a small internal heater at around 38C+/- 0.5C for a full season taking less than 2 watts of heater power on the coldest days.

Jules - K2KGJ
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