Messages

586

General Radio Discussion / Re: 49 MHz Range Testing Part 15 Experimentation

« on: October 21, 2019, 1714 UTC »

Military (Magnavox) PRC-68A or B are good 49MHz radios if you can find them. Last pair I had went to eBay a decade ago. They put out about 1 watt on fresh batteries.

Czech Army Military RF-10 radio sets are all over eBay for about $100-$150.

The other surprisingly impressive 49MHz radios are the old style baby monitor base stations. Some of those could be tuned up to a half watt or so and with an outdoor antenna, could be received well over a mile away with a Realistic talkie.

The old style baby monitors are still in use around me (at least to some degree).  One of them appears to be either putting out more than the legal amount of power or is just in a really good location/running a really good antenna.  It does about 1/3 of a mile or so on 49.830 MHz. 

I'm taking a look at the RF-10 manpack radio sets on eBay now.  Pretty decent specs, reminds of me of the PRC-8/9/10 series.  1 watt TX power 44.000 MHz to 53.975 MHz.  49.850 MHz/49.875 MHz lol

587

FM Free Radio / Re: 107.7 FM Virginia House Radio - Richmond VA 5 October 2019

« on: October 16, 2019, 1533 UTC »

Tuned in at 1126 local time to hear several seconds of dead air followed by full ID - Virginia House Radio Richmond Virginny at 1127 local.  SIO 444 to SIO 555.

588

10/11 meters / Re: 11 meters is active 2140 UTC 9 October 2019

« on: October 14, 2019, 2214 UTC »

I haven’t heard nearly as much activity on 27.455 MHz USB as I heard in years past.  It’s still active for sure.  When the 26.705 MHz / 26.715 MHz guys are booming in and the other 26 MHz freeband frequencies are busy with Spanish speaking stations that’s generally a sign 27.455 USB will be busy. 

The Caribbean stations on 26.705 AM / 26.715 AM sometimes use 27.455 USB or 26.555 LSB for 11 meter SSB. 

589

FM Free Radio / Re: 107.7 FM Virginia House Radio - Richmond VA 5 October 2019

« on: October 11, 2019, 1621 UTC »

SIO 555 signal near the center of downtown (a couple blocks away from the State Capitol) with more old time country music at 1215 local time.  I heard the usual prayers yesterday around 1615-1625 local time....the preacher specifically mentioned “ The Virginia House Radio “ at one point - audio could have been live, could hear churchgoers in background at points. 

590

Equipment / Re: USB Pirate Station, audio bandwidth

« on: October 10, 2019, 2251 UTC »

There's a huge amount of variation between stations as far as mode and bandwidth (and transmitter).  For SSB / USB stations, the usual 2.4 kHz - 2.7 kHz or so is pretty common.  Other US pirates have high end transmitters and do 5 kHz or even 10+ kHz wide SSB signals. 

There are still plenty of American shortwave pirate broadcasters that use good ol' AM. 

591

General Radio Discussion / Re: 49 MHz Range Testing Part 15 Experimentation

« on: October 10, 2019, 2245 UTC »

I have a land mobile license (in addition to a ham license and a GMRS license)...it would simply be a question of adding frequencies to the license, which is very simple.  There are plenty of available channels in the 30.580 MHz to 31.980 MHz and 35.020 to 35.980 MHz ranges...plus a few more if you include the 27.430 MHz, 27.450 MHz, 27.470 MHz, 27.490 MHz and 27.510 MHz/27.530 MHz (low power) frequencies and 29.710 MHz, 29.730 MHz, 29.750 MHz, 29.770 MHz and 29.790 MHz land mobile frequencies available for mobile use. 

A lot of the low split radios are on the market (those that cover the 33 MHz fire frequencies) for sure, same with the middle split (36-42 MHz for Motorola gear if I remember correctly), seems like the lower and upper splits (29-37 MHz or thereabouts and 42-50 MHz) are more available on the secondhand market.  Lots of options.

The 39 inch telescopic whip seems to be the way to go.  It was simple enough to do an antenna swap - I'll pull the radios apart again and see about adding a counterpoise. 


Update:

I did some more testing with the telescopic whip equipped Maxon PC-50 (I now have three of them). This time I  used a different known 49 MHz signal (this one on 49.860 MHz / 49.865 MHz - I think it’s probably on 49.862 MHz or 49.8625 MHz - my scanner only does 5 kHz steps from 17 MHz to 108 MHz and the Maxon PC-50 is channelized).  I’ll say 49.86 MHz (aka Channel C).

Anyway, simply replacing the rubber duck with the whip seems to increase receive range around 1.5x what it was with the rubber duck.  It’s now the same as the Pro-96 scanner connected to a 1/2 wave VHF high band antenna (not the best antenna setup I know). 

Since I have three PC-50s I will connect one of them to an outdoor wire antenna with counterpoise and then I’ll be able to do a side by side comparison of the telescopic whip and the stock rubber duck as far as receive performance goes.

I remember reading about directional wire antennas for tactical VHF FM use (30-76 MHz), including rhombic and other interesting designs for longer range with your handy PRC-25 or PRC-77 radio.  It’s in the field manual I have around here somewhere. 


Of course, the next logical step aside from secondhand low band gear on 49 MHz is a pair of PRC-77s on 49.850 MHz 

As I type that I’m reading about the Alinco DJ-V17L HT - it’s a “50 MHz” HT but apparently covers 36 MHz to 59 MHz transmit and receive.

592

Other / Re: RU chatters 3 MHz band 2205 UTC 18 Sep 2019

« on: October 10, 2019, 1936 UTC »

I've heard these guys on several Russian based SDRs (KiwiSDRs).  They're very active from 2 MHz to 3.5 or 4 MHz or so, the 2.5 MHz or 2.6 MHz to 3.3 MHz area seems to be the busiest though.

Here's a log from December 2018:

3053 kHz - Russian or Ukrainian OMs chatting, very good signals, one of the transmitters is on 3053.1 kHz, another one 3053.5
3073 kHz - S9+10db very good signal, 10-15 kHz wide AM, two ops, one on 3073.2 kHz, the other on 3073.4 kHz
3086 kHz - distorted audio, but strong signals, several stations chatting, one is on 3088 kHz, another on 3085 kHz
3100 kHz - more strong audio, with the usual frequency variation and wide AM signals
3113 kHz - very busy, more CB-like chatter and some dead carriers too, one on 3113.4 kHz
3120 kHz - another busy frequency, with lots of variation in frequency, one guy was down on 3117 kHz
3131 kHz - 3132 kHz vs. 3130 kHz, two replies to one transmission, you can see one of them swing up in freq. when the mic is keyed
3144 kHz or 3145 kHz - more of the same, 2-4 MHz Russian AM traffic...I wonder if these ops are using surplus military gear
3156 kHz - VERY strong (S9+20db) signal 3156.9 kHz at 2213 UTC (0013 local time) QRM from 3160 kHz
3160 kHz - weak carrier with some modulation, getting obliterated by the 3156 kHz / 3157 kHz crowd
3185 kHz - carrier on 3185.1 kHz, good signal with strong modulation, reminds me of 27025 AM when the band is busy

https://www.hfunderground.com/board/index.php/topic,48712.0.html

Apparently its either fishing trawlers using older-generation AM voice gear, freebanders/outbanders using old military gear, or some combination of the two.  The AM signals are generally pretty wide, and there's often a good kHz or so in difference as far as carrier frequencies go for a given QSO.  Both of those would indicate that they're using older radios with analog tuning.  I've heard them many times since on the various Russian SDRs, but I haven't logged them. 

It's like CB, they're almost always there! 

Messing around with a Russian remote receiver this afternoon, particularly the 11 meter band (which is quiet) and the 2-4 MHz border region between MF and HF, several posts here and elsewhere on the Internet have indicated to the use of so-called village radios in certain parts of Russia.  So, as always fascinated by bootleg two-way communications on weird bands, I decided to do some more monitoring.  No, I don't speak Russian.  Most of these transmissions, especially the ones in AM mode, are off-frequency.  Indications are that many of these folks are using surplus Russian military radios.

Logs, starting at 1600 UTC September 5th, 2017 (1900 Moscow time)


2880 kHz USB - Russian language
2900 kHz USB - Russian language, right on frequency, chatter similar to the 3 MHz AM signals
2915 kHz AM - Russian language
2920 kHz USB - Russian language, S5 to S7 signals nice audio
2995 kHz AM - Russian language, with QRM from 3000 kHz traffic
3000 kHz AM - Russian language, nearly nonstop traffic
3025 kHz AM - Russian language, several OMs talking, very strong (S9+ with powerful modulation)
3055 kHz AM - Russian language, weaker than 3025 AM, peaking at S4-S5, very chatty
3065 kHz AM - Russian language, all radios off-frequency
3080 kHz AM - Russian language, OM chatting very rapidly, strong AM signals S7 to S9+30db
3090 kHz AM - Russian language, OMs and YLs talking, most stations are off-frequency (3089 kHz, 3091 kHz, etc)
3105 kHz AM - Russian language, some with minor overmodulation, S9 to S9+30db very strong
3110 kHz AM - Russian language, lots of QRM due to signals squeezed together around 3 MHz
3115 kHz AM - Russian language, causing serious QRM to 3120 kHz AM and vise-versa (two QSOs going at once)
3120 kHz AM - Russian language, radio checks, very powerful AM signals here (strongest one S9+20db)
3125 kHz AM - Russian language, weak, getting killed by 3120 kHz
3145 kHz AM - Russian language, one station on 3144 kHz talking to another on 3147 kHz
3150 kHz AM - Russian language, different QSO from 3145 kHz, lots of QRM
3160 kHz AM - Russian language - signal strength weaker than most other logs
3170 kHz USB - Russian language, with QRM from 3175 kHz AM
3175 kHz AM - Russian language, several mentions of "microphona" and "microphone"
3200 kHz AM - Russian language
3210 kHz AM - Russian language, several OMs talking with strong signals
3215 kHz AM - Russian language, much weaker than strong signals on 3120 kHz
3225 kHz USB - Russian language
3255 kHz USB - Russian language
3320 kHz AM - Russian language, S4-S5 with lots of fading
3325 kHz USB - Russian language
3350 kHz USB - Russian language, with heavy QRM from CW signal on 3351 kHz
3355 kHz AM - Russian language
Modify message
« Last Edit: September 05, 2017, 1639 UTC by R4002 »

https://www.hfunderground.com/board/index.php/topic,37172.msg139123.html#msg139123

593

General Radio Discussion / Re: 49 MHz Range Testing Part 15 Experimentation

« on: October 10, 2019, 1712 UTC »

Well, I went ahead and swapped out one of the rubber duck antennas with a 39 inch telescopic whip antenna from eBay.  Preliminary testing indicates that it hears one of the nearby 49 MHz carriers (a baby monitor/open mic on 49.830 MHz) considerably better than the factory rubber duck.  Seems to double range at which I can receive that signal.  I don't know exactly where the transmitter is located because it can be heard over a relatively large area compared to other 49 MHz carriers I've used as "test beacons".   

For whatever that's worth.  I need to do some more testing with two Maxon PC-50 49 MHz walkie talkies using telescopic whips or one "base station" using an external antenna and another handheld PC-50 49 MHz radio with a telescopic whip since I have a reference test for base station with external antenna and another handheld 49 MHz radio with stock rubber duck antenna. 

I used to have a pair of RadioShack TRC-92 (I believe that was the model) 100mw single-channel CB HTs (100mw input power apparently, so about 50mw output power maybe?) with telescopic whips and crystals for 27.125 MHz aka CB channel 14.  The best range I got out of those was about 1/3 of a mile maybe a little more.  Then the first RadioShack FRS HTs hit the market and even the little entry-level FRS HTs on FRS channel 1 blew the TRC-92s out of the water.  Plus, no telescopic whip to worry about. 

If I can get similar range with these Maxon PC-50s I'll call it a success.  Of course a pair of Motorola MT1000 or HT1000 lowband HTs would work a lot better as far as range goes but I don't want lots of range.  A pair of full-power 40 channel CB handhelds with good antennas and decent VHF HTs (again with good antennas) gives me that range. 

Sometimes more coverage is a bad thing...in an emergency situation where somebody a mile away has a scanner/intercept setup they'll hear you if you're using a Baofeng or FRS or whatever VHF/UHF or CB handhelds to talk to somebody 500 feet away but they probably wouldn't hear you if you're using 49 MHz Part 15 radios.  Low probability of intercept.

I know that 49 MHz has almost no DX possibilities, and as far as Part 15 goes...22m or even 11m might be better options for DX but I also think it has an interesting niche use.  Maybe. 

594

10/11 meters / 11 meters is active 2140 UTC 9 October 2019

« on: October 09, 2019, 2142 UTC »

In-band channels are relatively quiet, but 26.705 MHz and 26.715 MHz are both quite busy with Spanish language chatter.  Busier than channel 6 (27.025 MHz) and the other usual legal 40 AM DX channels. 

Noted 26.725 MHz, 26.605 MHz, 26.585 MHz and several other low channels active with Spanish language traffic in AM mode. 

595

FM Free Radio / Re: 107.7 FM Virginia House Radio - Richmond VA 5 October 2019

« on: October 09, 2019, 1543 UTC »

Virginia House Radio Richmond Virginny with SIO 555 Downtown Richmond VA this morning (just shy of 0700 local time) and SIO 444 around 1130-1140 local time.  107.7 MHz FM.

They either adjusted their transmitter or changed it out - they’re not quieting 107.9 FM anymore - this morning I could hear another station clearly on both adjacent frequencies 107.5 MHz and 107.9 MHz without a problem. 

596

General Radio Discussion / Re: 49 MHz Range Testing Part 15 Experimentation

« on: October 05, 2019, 2111 UTC »

Those 43 MHz transceivers are apparently quite popular in Ukraine and Russia and elsewhere.  Used in ways similar to CB/11 meters.  They can be easily modified to do 25 watts output and cover 42.3000 MHz to 45.0875 MHz in 12.5 kHz steps.  Like 11m, its popular with taxis, car services, farmers and the like. 

At some point in the future I'll build a proper quarter wave wire antenna with counterpoise for 49 MHz.  Further scanning of the 49.820-49.900 MHz band has yielded more random FM carriers and open mics on various frequencies.  49.860 MHz, 49.865 MHz, 49.850 MHz, 49.830 MHz are all used in at least one spot near my house/office.  The more I research 49 MHz devices the more I realize the "band plan" is more like guidelines.  Lots of baby monitors use offset channels but also use 20 kHz bandwidth narrow FM - aka "25 kHz" (instead of the usual 11 kHz bandwidth aka "12.5 kHz") - same as lowband land mobile gear.

597

Peskies / Re: Scottish Peskies? 5000 USB 1815 UTC 18 Sept 2019

« on: October 05, 2019, 2106 UTC »

Nice catch - I've heard the usual suspects (Latin Americans speaking Spanish or Portuguese) on 5000 kHz USB before, and 5555 kHz / 5555.5 kHz, of course.  Always in USB.  North Sea oil workers sounds about right, or fishing fleets.  No engine noise in the background, I presume?

598

FM Free Radio / 107.7 FM Virginia House Radio - Richmond VA 5 October 2019

« on: October 05, 2019, 1402 UTC »

Virginia House Radio is back on 107.7 MHz FM in Richmond.  Hearing them with their usual fare in southside Richmond at 1000 local time. 

Good signal further away from downtown then I usually am.  Mixing in with DX QRM from the 107.7 WTOP translator/repeater.  Virginia House Radio is generally winning though. 

599

General Radio Discussion / Re: 49 MHz Range Testing Part 15 Experimentation

« on: September 29, 2019, 2118 UTC »

I’ve browsed through the Yahoo group and the UK guys on transmission1.  Seems like the Maxon PC-50 and Radio Shack 5 channel HTs were sold in the UK and well.  Seems like they weren’t very popular over there though. 

I’m thinking about either swapping the antenna connector for SMA as recommended, or putting a (long) telescopic whip in.  The TRC-512 radios would be much easier to do an antenna upgrade on.I was also able to find the TRC-512 service manual online. 

Given the significant range increase the antenna upgrade experiments produced I am hopeful that I can bring these radios to the 1/4 or so mile range I want.  I don’t want further range for the reasons SIGMA mentioned - super low power means lower probability of intercept (unless the people doing the intercepting are *very* close). 

I’ve thought about grabbing a couple MT1000s or similar Motorola lowband HTs, include the 49 MHz freqs, 6 meter stuff, the 47.420 MHz Red Cross frequency and some others.  Several utility companies in my area use 48 MHz and 49 MHz frequencies (49.580 MHz and below)...and the state Department of Transportation operates an extensive network on 45 MHz/47 MHz, with dozens and dozens of repeaters and lots of simplex use.

I’m sure there are clear frequencies in the 43/44 MHz region but there are several heavy construction contractors using those bands...and I’m not going to use the power company’s lowband frequencies for obvious reasons...

For now I’ll continue to experiment with short range/low probability of intercept purpose stuff on the 49.820 - 49.900 MHz band...49.875 being my primary frequency for now.

600

General Radio Discussion / 49 MHz Range Testing Part 15 Experimentation

« on: September 29, 2019, 1508 UTC »

I picked up a pair of Maxon PC-50 5 channel 49MHz band FM transceivers (they’re actually made by Midland apparently).  These radios are very similar to the Radio Shack TRC-512 and TRC-503 5-channel FM walkie talkies - same channel plan, same circuit board, etc.  The Maxon radios have removable antennas (!!) and, of course, they’re rubber ducks.

I did some basic range testing with the stock antennas and got about 90-100 meters away before the signal started dropping out.  I replaced the rubber duck on one with a 50-foot piece of wire and the range went up to 400 meters (1300 feet, around 1/4 of a mile) before the signal started dropping in and out.  This is in a heavily built up area too.  I used 49.875 MHz as it appears to be the less-used of the 49 MHz frequencies.  The Maxon and RS radios use a standardized channeling plan,

Channel A - 49.830 MHz
Channel B - 49.845 MHz
Channel C - 49.860 MHz
Channel D - 49.875 MHz
Channel E - 49.890 MHz

But my research indicates there is no official channel plan, only the band limits per Part 15: 49.820 MHz - 49.900 MHz.  Commercial/consumer equipment is limited to 10,000 microvolts per meter at 3 meters.  Baby monitors use random channel plans, often with 2 channels - 49.850 MHz and 49.870 MHz are popular pairs, as are 49.835 MHz and 49.865 MHz.  Yes, they are still making regular 49 MHz FM baby monitors today, most of them are 2 or 3 channel units...again with arbitrary channel plans (49.830 MHz, 49.850 MHz, 49.870 MHz seems to be pretty common too).

I’ve driven around with my scanner and have noticed three different open mics/baby monitors within a mile radius of my house on 49 MHz.  Two of them are on 49.830 MHz and the other is on 49.860 MHz (it sounds just as strong on 49.865 MHz, however...maybe it’s closer to 49.8625 MHz?).  The 49.860 signal is strongest in the downtown central business district away from residences and doesn’t have background noise and people talking like baby monitors do.  It’s not a birdie, multiple radios hear it....and it has the range you’d expect from a 49 MHz monitor transmitter...

One of the 49.830 MHz ones carries a pretty impressive distance, and this is with a scanner and an antenna tuned for 150 MHz.  Side by side comparisons between the Maxon 49 MHz walkie talkies and the scanner show that these little HTs have excellent sensitivity.

I plan on replacing the stock rubber ducks with telescopic whips and maybe getting a pair of RadioShack TRC-512 49 MHz radios, since they come with telescopic whips that could easily be upgraded.

The rules also state that while consumer gear is limited to the 10,000 microvolts/meter at 3 meters...hobby or home built equipment can transmit up to 100mw (measured at antenna terminals at the highest level of modulation) on any frequency within the 49.82-49.90 MHz band using any modulation type as long as it stays within the band.  Certainly a beacon opportunity there. 

Anyway, I see equipment on this band as serving a niche communications need.  FRS radios, MURS, and other VHF/UHF bands (even handheld CB radios) carry a lot further than these 49 MHz rigs do.  Cheap intra-squad radios for militia types maybe?