5

I used LiFePO4 (read: Lithium Iron Phosphate) for my dad's FT-891. The big advantages of LiFePo4 are: Very power dense, almost as much as Li-Ion, IIRC twice as much Wh/kg than Lead-acid Extremely safe: they don't short circuit themselves to flames, like Li-Ion does Flat voltage discharge characteristics: their nominal voltage is 3.2V and they stay at 3.2V ...


5

Portable antennas are always a compromise. The best antenna in terms of radiation efficiency will be the one that compromises the least. That means basically two things: make it big get it high (or install many radials to reduce ground losses) The best antenna in terms of portability will be: easy to move (small) easy to set up (not high) My advice would ...


4

An antenna design that requires grounding to suppress the common-mode or improve efficiency is a poor antenna design, unless significant effort is made to make a low-loss ground. For example, a quarter-wave monopole above a ground plane of radials or saltwater works well. A quarter-wave monopole with just a ground rod is as much a dummy load as it is an ...


4

End-fed half-waves (EFHW) are popular with SOTA operators, and they understand portable. If you'll be operating where there are trees, you can tie a rock to some cord, throw it over a tree, and hoist up a 10 meter piece of wire. If no trees, you'll have to carry a 30 ft fishing pole, but they can be found and the collapse to fit into a trunk. With a ...


3

Sealed lead acid batteries are heavy. I would not recommend them. lithium phosphate or lipo are lighter, but can be hazardous. in case of physical damage to the battery they can burst into flames or even explode. Lithium Iron Phosphate batteries are also light weight and are much safer. Bioenno is a well known battery vendor that has a wide selection of ...


3

I wouldn't risk directly connecting a 9.6v battery to a radio that expects 5-6v. The simplest solution would probably be the diodes mentioned in the comment to your question, but as the battery voltage dropped the voltage reaching the radio would drop as well, and as the battery got low the output voltage after the diodes might be too low to power the radio,...


3

There are a lot of variables involved in calculating the voltage on an antenna. If you require an accurate answer, the solution is to model or empirically measure the particular antenna in question. But for a very rough estimate, a 1/4 wave "counterpoise wire" is effectively one leg of a half-wave dipole, so you can treat it as such to get some number. In ...


3

I use telescopic fiberglass pole (10 to 12 meters is sufficient) and home made dipole antennas, single band and multiband (some trapped dipoles some linked dipoles). It does the job pretty well and it can fit in my backpack. I mostly use "hybrid" multiband dipole which consists of 20/17 meter trapped dipole and optional attachments for 40 meters. 20/17 ...


2

A Raspberry Pi running Direwolf is definitely a reasonable option. For a receive-only iGate, a number of people have had success with a Pi and an RTL-SDR dongle, running rtl_fm and direwolf. Nice and easy, no fuss, but of course it won't digipeat. I recently built myself a setup using a Pi and the DRA-818V chip (specifically, SV1AFN's DRA-818V board), with ...


2

For temporary weatherproofing my coax connectors I use a piece of bicycle innertube and a few cable ties.


2

For temporary connections, there's small "clamp on" cable boxes, something like: Definitely not "condensation-proof", but "should reduce quite significantly". Other than that, there's people that swear by the powers of the flexible LIDL or Aldi plastic radome, i.e. a plastic bag fastened with rubber bands or whatever around the parts to be protected. I can ...


1

In your diagram you show 1/2 wavelength vertical and using a combination of ladder line and coax to do impedance matching. This means usual advice about 1/4 wave vertical does not apply here. Imagine this antenna as a half wave dipole that has been flipped from horizontal to vertical. Dipoles do not need an RF ground. You do not need a ground spike or an ...


1

If you want 20 A, then lead-acid batteries will be too heavy. You would want some kind of lithium-ion battery. Lithium ion phosphate batteries are popular for this sort of application, like the kind that Buddipole sells. A few caveats: all this stuff will be really heavy by backpacking standards: the radio alone weighs 2.45 kg (5.4 lbs). Of course there'...


1

You might find it more cost effective to buy a relatively inexpensive, lower power radio (even QRP class), and couple it with an amplifier to get your desired power level. There is a fairly broad selection of lower power "all-band" portable/mobile HF rigs available, some in "some assembly" form for under US$200. For only 100W output, you ought to be able ...


1

Your are rightly concerned about dew infiltrating the connector. This can cause corrosion over time and moisture can build up to the point that short circuits result. But, if you only leave the antenna outdoors for a day or two at a time and not in the rain, it's unlikely you need very much moisture protection. I treat the threads of all PL259/SO239 ...


1

The RX iGate with a RTL-SDR dongle is pretty easy to setup. The hard part of a TX digipeater is keying the radio,like hobbs mentioned. I bought a Argent data systems t3-micro in hopes of making a fill-in digipeater or using a spare mobile radio for TX while driving; depending on that I needed. I should get back to that project...


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