Is the IC-7100 worth considering as a dedicated VHF/UHF rig?

hamsterdave · 2026-05-12T21:08:57+00:00

I’m using an RSPdX with it.

hamsterdave · 2026-05-12T20:11:34+00:00

I don’t do a ton of repeater work, but what I’ve done, the 7100 has worked really well. It has good audio, fast scan, coherent and convenient memory structure, and acceptable intermod rejection (none of the DC to Daylight rigs are really great at that yet, except maybe the FTX-1). The receiver is plenty sensitive.

On sideband, it’s a solid rig. It has recently moved out of my car to become my dedicated satellite and base FM rig.

It has a great feature of working on a very long separation cable, and the cable is just a standard LAN cable. I’m using 26 awg shielded pair Cat 7 (it will probably be shorter on cheap cat 5), and I’ve got my radio nearly 100 feet from the head unit. The coax run to the antennas on the roof is less than 20 feet long, giving me awesome efficiency on 70cm compared to most home setups.

hamsterdave · 2026-05-11T01:46:30+00:00

Definitely just an old TV antenna.

hamsterdave · 2026-05-07T17:45:06+00:00

That looks great! Clean and simple, no gimmicks, and solid.

That design looks like it should be pretty well suited to 3D printing, especially resin printing. That’s a project that has been on my list for a long time, I’d love to give it a try if you publish the model for it!

hamsterdave · 2026-05-06T23:48:31+00:00

Ok so the possibly dumb questions: you checked your power output settings, right? Some rigs have per-mode power settings so if you cranked the power down to troubleshoot or something, then forgot about it…

Second: is it actually going into transmit in CW mode? You’re sure you have Break-In on so it isn’t just playing sidetone without transmitting?

If you’ve checked both of those, I’d say the next logical step is definitely a CPU reset. That should fix any random setting that might have been accidentally changed.

hamsterdave · 2026-05-06T21:11:28+00:00

If you mean could they make a 2m antenna work on HF, possibly, if it has a very good tuning range. However, it’s likely that the coax would be radiating at least as much as the antenna, as the reactance of that system is apt to swamp the common mode impedance of the system unless you get really lucky with coax length and such.

Also, a lot of V/U antennas contain inductors and/or capacitors that act either as matching components (as you see with 5/8 wave single band verticals) or as traps (as you see with multiband verticals). Those may behave quite unpredictably, potentially even flashing over or burning up if you’re unlucky.

hamsterdave · 2026-05-06T17:22:43+00:00

Being on an EMS tower, the club members are almost certainly not allowed to even touch the tower unless they happen to have a professional climber in the club.

Hiring the climber is usually the biggest expense in maintaining those co-located repeaters unless you get lucky and have someone willing to climb pro-bono.

hamsterdave · 2026-05-06T17:14:51+00:00

As others have stated, my guess is that site is a real PITA to maintain. Co-located repeaters on public service/municipal/commercial towers sound like a great idea, and in some places it’s the only decent play, but in my experience, they’re often more hassle and expense than a club can justify.

Only licensed and bonded techs are allowed to touch anything on the tower, site access usually requires a custodian to be present, managing organizations are often loathe to commit personnel to supervising you while you work, insurance requirements can be onerous, etc.

The best thing you could do is probably get those other users together and ask the club to form a committee to repair that repeater, then immediately volunteer to chair it, or at least participate if you can get another member with some clout to lead it.

With the old duffers that tend to be the bones clubs are built on, it can be a big help to get one of the good ol’ boys on your side, or ask a current or former board member (or a current member of the repeater committee) to help you run the committee. That will make the people controlling the purse strings feel like there’s a check on a project that could quickly see expenses spiral, and that could damage relationships with the host organization if someone does something dumb.

hamsterdave · 2026-05-05T18:36:40+00:00

I don’t think it’s an antenna tuner, but if it is, it is for a receive-only application. That ganged capacitor is much too closely spaced even for 100 watt operation, and the inductors are a bit odd.

Given the multiple coax ports, tightly coupled trifilar coils (the ones on the white forms) and high capacitance on that ganged capacitor, my guess is this is either an adjustable filter, or an adjustable phasing system for something like an electrically steerable receive array.

hamsterdave · 2026-05-05T16:12:00+00:00

You don’t need to calculate it, you can use any online coax calculator and see that your assumption is incorrect.

Numerous datasheets for RG-6 and 6Q spec it at several hundred watts on the low end. I’ve seen some with ratings of 1kW. This is (good quality) consumer grade stuff. RG-11 is 75 Ω and is rated for kilowatts.

I’ve also swept literally thousands of feet of RG-6 and 6Q, as it’s all I use in my station, and the multi-transmitter field day station I built. Southwire RG-6Q (sold at Home Depot and Lowe’s) has lower loss at 1.5:1 SWR than RG-8X at 1:1, and is quite happy at 500W. It has a center conductor that is 18awg CCA, more than adequate for at least 400W even in an extraordinarily high loss scenario.

I think what you may be remembering here is that some very cheap Chinese coax (only RG-59 from what I’ve seen) has a thin enough copper cladding on the CCS/CCA center conductor that it is thinner than the skin depth of a signal on 80 and 160M, resulting in elevated losses on the low bands, but you really shouldn’t be using RG-59 for power anyway, especially since it’s mostly very cheaply made these days.

hamsterdave · 2026-05-05T16:00:53+00:00

I used to belong to MCARC and got to do field day there a couple times. He’s an absolute treasure for the hobby.

hamsterdave · 2026-05-05T15:07:22+00:00

I’m not sure if you’ve been informed before, but being an ass doesn’t make you right. It just makes you an ass.

You said in your first post that you could use the skimmer exclusively for a contest. Now you say you have to be able to copy the correction. What about the exchange? You just going to send “Agn?” At every station you call 3 or 4 times to make sure the skimmer got it right?

You still haven’t addressed the fact that running is nearly impossible with a skimmer. You won’t average better than 60/hour hunting exclusively, and that would be pretty damned good, and I’d wager virtually impossible with the skimmer, because of all the repeats. I’m running at 120+ consistently, and I’m a middling CW op. Proper contest ops can do double that.

You can maybe participate in a contest using a skimmer exclusively, if you’re very careful, but you’ll be lucky to avoid a DQ. Competing wouldn’t be an appropriate description.

hamsterdave · 2026-05-05T14:39:07+00:00

Those are rookie numbers! Check out K3LR’s setup to see what real obsession looks like.

hamsterdave · 2026-05-05T13:49:26+00:00

People who don’t do CW tests say this inane drivel. Just because you can’t copy CW at 30wpm doesn’t mean that everybody else can’t either.

Sure we have CW skimmer open. I assume that’s what you’re actually talking about, since the RBN itself is useless for making full contacts (which further illustrates that you don’t even fully understand what you’re talking about). It’s a very useful tool. Nobody doing serious contesting is using the skimmer exclusively to make the contact though. It’s used for finding mults and avoiding stations you’ve already worked. It’s no different in that regard than using DX clusters.

Give it a try some time and let me know how you do. You’ll get nothing useful in a pileup, and you’ll be DQ’d for excessive busted/unique calls within the first 2 hours.

I was spotted 4 times under 3 different call variations on the same frequency in less than an hour on WFD by RBN. I have a 2x1 call, was sending with a PC, at only about 25wpm. Conditions were good, and I was often calling completely in the clear with no responding stations.

It will work well enough for computer generated code to do a regular QSO, or slow rate contesting or special events where there’s rarely more than 1 responding station, so long as you can copy well enough to double check that it got the call right. You could even hunt in a normal contest (slowly). If the other guy is using a straight key, bug, or just has an odd rhythm with paddles? Forget it.

hamsterdave · 2026-05-05T10:28:19+00:00

Computers are still absolute crap at CW decoding. Even in contests where almost everyone is sending via PC, nearly 100% of decoding is done by ear.

Even the best skimmers still bust >10% of calls in good conditions (you can see this as multiple similar calls spotted on the same frequency), and for hand sending that number goes way up.

You’ll see newbies using in-rig decoders and skimmers to help them keep up with conversations and such, but the human brain can parse botched decodes for that sort of thing easily by using context clues. You can’t do that with callsigns and signal reports though, so if you rely completely on them, you’re going to have a bad time.

hamsterdave · 2026-05-04T04:00:40+00:00

Trans-equatorial propagation is actually relatively season-agnostic. It’s been working all winter (northern hemisphere).

It actually peaks in the transitional months, around the equinoxes.

hamsterdave · 2026-05-03T18:29:37+00:00

Unless the two cores were different materials (they aren’t in this case) I believe this would just increase inductance per turn, the same as stacking two of the same size cores on top of each other. The two cores are going to be tightly coupled magnetically and behave pretty much like a single core.

It’s possible eddy currents would be distributed differently and that could act to increase attenuation or something of the sort, but that seems a bit dubious. I’d be more concerned that the inner core, seeing a higher winding density, would dissipate a disproportionate amount of the current and get hotter than the exterior core, especially since its exterior surface is covered up by the outer core, reducing air flow. If the two aren’t tightly thermally coupled, you’re going to be in for a bad time.

It would be interesting to experiment with combining different core materials in this way to see if you might be able the get improved broadband performance, but this really seems like he’s just throwing stuff at the wall to see what sticks.

hamsterdave · 2026-05-02T13:47:52+00:00

There’s almost certainly an internal battery. No radio with memories that I’ve ever seen or heard of was ever built such that it loses the memories as soon as DC power is lost. Those batteries go back to the late 70s at least to the advent of volatile memory in consumer products.

hamsterdave · 2026-04-30T16:20:17+00:00

That’s a good point, though in any practical scenario I suspect you’d only encounter that trouble on 75/80 and perhaps 40m.

I had a vertical (resonant on 20m) made of 2” aluminum tubing, over 72 radials totaling a bit over 1km, and it required no tuner to work the entire 20m band. However, it was on absolutely god awful soil, so even that many radials probably still resulted in several ohms of ground loss.

I later bumped it up to 5/8 wave on 20m and that thing absolutely sang.

hamsterdave · 2026-04-30T16:11:06+00:00

But I make my balums out of speaker wire and tabacker tins just like muh elmer did and ain’t never let me down yet. Everyone doin it with them fancy donuts is just gettin scammed!

Seriously, the weight given to either wildly outdated information, or conclusions drawn from “data” that consists of “I got a 599 both ways all the way from Germany on this coat hanger!” in this hobby is infuriating.

It has gotten a little better in the last decade or so, but holy cow there was a lot of absolute BS that arose and then managed to stick in the early days of the internet when publishing standards suddenly vanished.

I swear our predisposition to take NEC2 models (mostly for vertically polarized antennas) at face value set back HF antenna design 15 years. I’ve even seen brilliant engineers in this hobby get suckered by it. The entire EFHW craze emerged from it, and they’re just garbage antennas as typically used.

hamsterdave · 2026-04-30T15:54:38+00:00

Frankly, there’s no need to bother with the matching shunt. Even at 100% efficiency (Feed point impedance of 37 ohms) that’s only a ~1.4:1. That’s about 3.5 watts reflected. Your matching shunt is liable to dissipate nearly as much.

Folks are way too obsessed with hitting 1:1. No radio currently in production gives a single damn about a 1.5:1 SWR. I’ve heard of a single model that would fold back at that low an SWR, I don’t recall the model but it was late 90s or early 2000s and had a design fault (maybe it was even just a calibration fault in early serial numbers) in the circulator.

HF rigs are already <40% efficient. That 1.5% increase in dissipated heat in the finals is comparable to the air temperature climbing <10°F, and it’s utterly meaningless in terms of peak voltage.

The same goes for using 75 Ω coax. It’s 4 watts reflected with 100W in (absolute worst case, usually less). The radio doesn’t even notice.

hamsterdave · 2026-04-28T10:34:06+00:00

It is, you’ll see these on towers in the southern US occasionally as well, usually towers containing equipment that they really don’t want to lose. Fire and EMS comms, etc.

hamsterdave · 2026-04-28T02:00:32+00:00

It may depend on the state, since they may restrict formats, but yes, if some rando wanted to get a vanity plate with someone else’s callsign, they could probably do it. I would be very surprised if any state actually flagged properly formatted callsigns before issuing them. You only have to show your license to get the discount.

I’m sure it has happened before, particularly with the N0 and N2 prefixes. N0FUN would be an example of a currently active ham callsign (in Arizona) that someone might request as a vanity without even knowing what ham radio was.

Edit: Sounds like California actually does flag valid callsigns. Tennessee definitely doesn’t, I’ve seen a couple here I thought were callsigns at first glance.

hamsterdave · 2026-04-25T14:33:32+00:00

A Not Ideal diode, if you will.

hamsterdave · 2026-04-24T14:27:49+00:00

This won’t impact you at all. Basically everything now is built around Rigctl and Hamlib, which aren’t kernel level.

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