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Ham College 73

31 January 2021 | by George W5JDX | Leave a Comment (1)

Ham College episode 73 is now available for download.

Extra Class Exam Questions – Part 11.
E2E Operating methods: operating HF digital modes.
1:07:26

George Thomas, W5JDX, is co-host of AmateurLogic.TV, an original amateur radio video program hosted by George Thomas (W5JDX), Tommy Martin (N5ZNO), Peter Berrett (VK3PB), and Emile Diodene (KE5QKR). Contact him at [email protected].

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What Cows Think About 146.52 MHz

31 January 2021 | by Bob KØNR | Leave a Comment (1)

I see a lot of cows standing around in Colorado ranch land, and I often wonder what they are thinking. As a result, I’ve been experimenting with a series of graphics that show cows standing out in the field thinking great thoughts. Surprisingly, they are often thinking about ham radio topics. Who knew? I’ve posted these on Twitter (@K0NR) which usually generates some responses.

Recently, the cows were thinking about the 2m FM calling frequency.

Some of my international followers pointed out the 2m FM calling frequency is not 146.52 MHz in their country. Sometimes it is difficult to localize VHF content, so sorry about that.

EA3IEK commented that the calling frequency should also be the listening frequency. (This is the crux of the problem with calling frequencies on 2m FM…what is the best ratio of calling and listening?) So I quickly modified the photo.

Then I could not resist posting this one, inspired by Joey on the Friends television show. Moo. It’s just a cow’s opinion.

73 Bob K0NR

The post What Cows Think About 146.52 MHz appeared first on The KØNR Radio Site.

Bob Witte, KØNR, is a regular contributor to AmateurRadio.com and writes from Colorado, USA. Contact him at [email protected].

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ICQ Podcast Episode 343 – QSO Today Expo

31 January 2021 | by Colin M6BOY | Leave a Comment (0)

In this episode, Martin M1MRB is joined by Dan Romanchik KB6NU and Edmund Spicer M0MNG to discuss the latest Amateur / Ham Radio news. Colin M6BOY rounds up the news in brief and in this episode’s features is the QSO Show Expo.

ICQ AMATEUR/HAM RADIO PODCAST DONORS

We would like to thank our monthly and annual subscription donors for keeping the podcast advert free. To donate, please visit - http://www.icqpodcast.com/donate

- FCC - Radio Users Reminded Not to Use Radios in Crimes - 3,500 German Radio Interference Complaints in 2020 - JARL Wants to Increase Youngsters Amateur Radio Experience Opportunities - Sweden's Oldest Radio Ham on TV - City Antenna Law Upturned By FCC Ruling - Distance Learning Course for Full Exam - Intrepid-DX Group Invites Nominations for Intrepid Spirit Award

Colin Butler, M6BOY, is the host of the ICQ Podcast, a weekly radio show about Amateur Radio. Contact him at [email protected].

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Do you remember your first?

28 January 2021 | by Mike VE9KK | Leave a Comment (18)

I was doing some cleaning around the house the other day and came across a QSL card of the very first contact I made. It was June 6th, 1989 and I was pounding out CQ with my Bencher BY-1 Iambic paddle. I had a script all made up with a step by step CW QSO contact information. As I very well remember things did not go as planned. I now know I just was experiencing what any new green CW op would experience. I was listening to the code that was being sent and writing it down on paper but then I missed a letter and started to concentrate on the missed letter. This meant I missed even more code and was lost in no time. I had to do I mental reset and carry on. At some points, I fell into the bad habit of counting dits and dahs and not hearing the rhythm again it was panic setting in. When it came time to send I wanted to for some reason send just a bit faster than I was receiving well that did not work out too well when I was receiving and the code was coming back at me just a bit faster! While on the subject of sending I did find myself messing up letters and having to send words again. Then frustration set in which made it worse, but I did complete the QSO. As stressful as it may have seemed I was thrilled and could not wait for my next contact.

At that time my station setup was the Icom IC-745 it was second hand but I loved it and had served me for many years. My antenna was the Crushcraft R4 vertical antenna which for my location was the best solution. I did not own the house I was living in so a tower and beam were out of the question. Also, the lot was small so no room for ground radial. The R4 answered my needs as it did not need ground radials and had a very small footprint. As stated earlier I had the Bencher BY-1 key.

Can any of you remember your first contact and the gear you were using at the time?

Mike Weir, VE9KK, is a regular contributor to AmateurRadio.com and writes from New Brunswick, Canada. Contact him at [email protected].

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LHS Episode #389: Jailbird Jamboree

25 January 2021 | by Russ K5TUX | Leave a Comment (1)

Welcome to Episode 389 of Linux in the Ham Shack. In this episode, the hosts discuss illegal activity on the air, the purpose of amateur radio, a remote head unit for the Icom IC-7100, Linux on the Apple M1 chip, a new frontier for Red Hat Enterprise Linux, ethical open-source licenses and much more. Thank you for tuning in and have a great week!

73 de The LHS Crew

Russ Woodman, K5TUX, co-hosts the Linux in the Ham Shack podcast which is available for download in both MP3 and OGG audio format. Contact him at [email protected].

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AN/GRC-9 aka “Angry Nine”

24 January 2021 | by Richard AA4OO | Leave a Comment (12)

AN/GRC-9 - Long lived military comms

My lovely (and radioactive) RT/77-GRC/9

I don't recall where I first read about the Angry Nine, but it captured my imagination. I read everything I could find about them and decided it would be great fun to operate such an antique on the ham bands. There is no logical reason to desire such a QRP radio. The low power output on CW is indeed, 5 watts and high power is a pileup busting 15 watts. The AM transmission are 1 watt and 7 watts respectively. That's almost QRPp for AM mode.

I'd had some experience restoring old tube equipment; my Heathkit HW-101, Knightkits VFO and Hallicrafters keyer, and I figured I'd take the next plunge and learn to use a receiver-transmitter combination and see how mobile high-voltage power worked from Vibrators and Dynamotors.

These radios seemed to have been more plentiful in the surplus market 10 - 20 years ago. Now you'll occasionally see one come up on eBay or other sites, but often times they are in very rough shape or the they are foreign language versions. I bid on a few auctions over the past couple of years and the bidding always exceeded my threshold for what I thought it was worth. The one above was part of an auction from an individual who had actually trained on these units prior to deploying to Vietnam. Later in life he became interested in finding one and spent time in military surplus warehouses going through pallets of equipment to find one in good shape. This particular unit is made up of a Lewt manufactured transmitter and a Telefunken receiver. The original owner preferred the receiver characteristics of the Telefunken over the Lewt manufactured model, so he paired the two.

Many of these old units are radioactive, due to the radium paint used on the front panels to make the lettering glow in the dark. This particular unit is off the lower scale on the Geiger counter and must be handled with care. Basically, I have to be careful to not touch my face with my hands after operating the unit and wash my hands thoroughly. Radium emits Alpha particles, which are not especially strong but the resultant radioactive dust from the front panel shouldn't be breathed or ingested.

Hot receiver, in more ways than one

The AN/GRC-9 is a set of components primarily comprised of the RT-77/GRC-9 receiver-transmitter, capable of operating between 2-12 MHz in CW, MCW and AM modes. MCW is a modulated form of CW that can be received by radios that do not have a BFO (i.e. a normal AM receiver).

It is a mid to late 1940's design and was first documented field use in the Korean War, and was in active use through the Vietnam War and continued to be maintained in US military warehouses until 1974. It was in use by other nations long after, most notably the Dutch military.

Out of the case, tracing a low B+ power problem

Close up of the bottom of the receiver board

Transmitter

Power on the move

Designed to be used in the field, both vehicle mounted and carried by mobile infantry; there were a number of ways to supply power to the unit. There were a few different Vibrator/Dynamotor units, that could operate from common DC voltages of the time (6v, 12v, 24v) as well as a hand cranked, field portable generator.

Keep in mind that the state of the art at the time of its design used vacuum tube technology and in the case of the RT/77-GRC/9 it required the following voltages:

Transmitter Plates -- 475 - 580 v @ 100ma
Transmitter Filaments -- 6.5 - 6.6 v@ 2 amps
Receiver Plates -- 105 - 120 v @ 45ma
Receiver Filaments -- 1.35 - 1.5 v @ 500ma
Keying Relay -- 6.0 - 6.9 v @ 575ma

That's a tall order for mobile and portable power supplies but designers in the 1940's were quite clever in packing power supply units. I managed to obtain both the hand cranked GN-58 generator with the base chassis and seat for portable operations, and a DY-88 for fixed / mobile operations.

DY-88 mobile power supply

DY-88 set to 12v powered by Amateur 12v supply

Vibrator power supply for low B+

Power filtering

I supply the DY-88 from either an RV battery or an amateur 12v power supply. When in Standby the DY-88 draws less than 1 amp, but placing the radio in Send mode switches on the Dynamotor which draws 12 amps @12v, without key-down and up to 14 amps on high-output key-down. It will drain an RV battery pretty quickly at that rate if the radio is left in Send mode, and works an amateur power supply pretty hard as well. So don't expect to operate remote off a battery alone for too long if your having lengthy QSOs. An added benefit of the DY-88 is that when the enclosed Dynamotor is running you'll have a nice extra 85 dB of generator noise to accompany your listening pleasure.

GN-58 portable field hand-cranked power supply

Generator head in carry bag

NOS Shiny

Deployed

The GN-58 is a tough workout since it has to be cranked by hand at 60 rpm continuously. Obviously, you need a partner unless you can figure out how to crank it with your feet while sending CW. You will also want that partner to help you carry the GN-58, and the accompanying accessory bag for the chassis and seat. IT'S HEAVY. I haven't weighed everything, but according to the manual that came with the set, the radio / generator / accessories including antennas comes out around 120 lbs.

If you have a BC-48 battery hooked up then your human power supply can pause cranking while your receiving. I have a BC-48 battery enclosure that has been gutted of the original, long-dead material and replaced with 10x 9v batteries in series for the low B+ and two D-Cell batteries in parallel for the receiver filament supply.

Accessories

Bag of goodies

The radio itself has a carry bag, as well as a bag for the GN-58 legs and seat, the vertical antenna, and miscellaneous.

There's another bag (shown above) for carrying power supply cables, keys, hand mic, long wire and doublet antennas, external speaker, torture device headphones, torture device in-ear phones, as well as a box of spare tubes for the radio.

If you're traveling in a squad sized group, then many hands make light work, otherwise you're going to be making a lot of trips hauling your QRP rig up the hill.

Headphones

These Western Electric headphones clamp tightly over your ears sealing out QRM and squeezing your head like a vice. After 10 minutes I was confessing to sins I'd never committed.

In order to use the headphones the RT/77 receiver must be removed from the case and an impedance switch on the back, changed from 4000 to 250 using a screwdriver. The ham I bought my set from had constructed a CW audio filter along with an impedance switch on an outboard box, that allowed the use of the headphones without switching the impedance on the receiver unit.

Homebuilt CW filter with impedance switch

Speaker

The external speaker is a rugged, high impedance device (4k Ohms), that after all these years can still output audio at high volumes without distortion. It has a built in thumbscrew clamp that allows it to be attached to vertical or horizontal objects.

Alternately, the thumbscrew can be used in combination with the vice-like headphones to extract information from a prisoner.

Antennas

The AN/GRC-9 comes with 3 antenna systems; a multiple section, whip vertical for quick field setup and mobile use, a long wire that can be quickly deployed in a fixed station as a sloper, and a doublet for best reception, transmission in a fixed location.

For testing purposes I have my radio hooked up to my 80m Windom, which it tunes very nicely on 80m, 60m, 40m and 10m bands.

When the weather warms a bit I will be taking the radio out for some portable use and I'll try it out with the antennas that are part of the AN/GRC-9 set.

Spares

As a military radio, it was expected that repairs should be performed in the field when possible. The radio shipped with spare tubes for the receiver-transmitter, as well as spare tubes and vibrators for the DY-88 power supply.

More to come

In the few days I've had the AN/GRC-9 the only problems I've encountered have been related to the old DY-88 power supply. Old vibrators cans are generally seized up, as was the case with mine. Eventually mine became un-stuck after repeated applications of power but there are some methods to restore truly frozen ones using AC current and light bulbs (see Notes section below).

I've made about half a dozen contacts on the ham bands, including a 40m contact to a station in TX which is kinda DX for my locale. I've received nice signal reports. I've specifically asked stations about my "chirp" during QSOs and they've reported it as "not bad" and "charming". When operating from the VFO (master oscillator) rather than a crystal, the GRC-9 will "chirp". It was considered an acceptable design trade-off at the time. I've listened to the transmitter from a remote WebSDR station to hear the chirp for myself, and I agree that it isn't extreme and lends some character to the station. The unit does drift about 200 Hz during a QSO which I also think is quite acceptable for it's age. It's possible that if I spent more time in Send mode prior to a QSO to allow the transmitter tubes to warm up the drift might be lessened, but keeping the radio in Send mode puts quite a load on the power supply (both the 12v supplying the DY-88 and the human cranking the GN-58).

The RT-77 Telefunken receiver doesn't offer much in terms of selectivity and on a crowded band there's a lot of stations to contend with in the passband. The outboard CW filter deals with this nicely, but it is so narrow that when shifting from Send to Standby, the resulting frequency shift often throws the station I'm receiving out of the filter's passband, so that's a bit tricky.

The receiver's tuning knob also is very coarse, in that fine adjustments are made by breathing on the knob. However it has zero backlash, which is amazing in a piece of equipment this old. The markings on the receiver are in 50 kHz intervals so the only way to really figure out where you are is to look at RBN for your spot.

50 kHz spacing when reading the frequency on the receiver
Note the 7.2 is 7.200 MHz in the 40m band

Images

Enjoy the pictures of the AN/GRC-9

Notes

Instructions for restoring a vibrator to operation

VB-1 and VB-7 are interchangable. I think I recall reading somewhere that VB-7 is a "lightweight" version of VB-1 but I won't swear to that.

The base is 4-pin, and the pin numbers are counted as on a vacuum tube with the same base. I wish I could post an image here without uploading it somewhere but if it's possible I've not figured out how to do it. The pins count clockwise from 1 to 4 looking at the bottom of the vibrator or the wiring side of the socket. The two large pins are 4 and 1 and the two small ones are 2 and 3.

There are two basic types of vibrators, called Series and Shunt. The Series type has a contact in series with the coil. VB-1, 7 and 16 are all Series types. I'll skip the Shunt type for now.

Pin 1 is common. Pin 4 is coil. Pin 2 is the NO (Normally Open) switching contact and Pin 3 is NC (Normally Closed). To test a VB-1/7, use an ohmmeter to check continuity from 1 to 4. If the reading is infinity, the coil could be open but this seldom happens. The problem is probably the vibrator contact. If the reading is a few ohms, connect +6 VDC to Pin 4 and -6 VDC to Pin 1. The vibrator should run. If it doesn't, most likely the contact is welded. About the only solution is to open up the vibrator, unstick the contact and try to burnish the burn marks out of the contact.

If the vibrator does run, go to the end of this screed and do the final test.

If the reading is infinity, here's how to use the two or three lamps to (usually) fix the vibrator. SAFETY NOTE: bear in mind you are dealing with either 120 or 220 VAC. If you jury rig the hookup, do all of your connections and disconnections with the "rig" not connected to the AC line. In other words, don't touch anything except the plug on the line cord or (if you go to that much trouble) the ON-OFF switch when the line cord is plugged in.

Connect the hot side of the AC line cord to one side of both lamps. Connect the ground side of the AC line cord to Pin 1 of the vibrator (or socket if you use one). Connect the other side of one of the lamps to Pin 4 and the other lamp to Pins 3 and 2. If you splurge and use three lamps, connect the "cold" side of the second and third lamps to Pins 2 and 3 respectively.

Check all the wiring and when satisfied all is OK, plug in the line cord. Probably nothing will happen immediately. Within a few minutes to a few hours lamp 1 should begin flickering and you should hear the vibrator hum. Run the test until the second lamp begins to flicker or until both the 2nd and 3rd lamps flicker.

If you are only using two lamps, when the 2nd lamp begins to flicker, wait 1 or 2 minutes then remove power (unplug the line cord). Connect the 2nd lamp only to Pin 2 and plug in the line cord. If the 2nd lamp flickers, remove power, move the 2nd lamp connection to Pin 3 and apply power. In either case (with the 2nd lamp now connected to pin 2 or 3 only), let the test run until the 2nd lamp again flickers.

For a final test, connect one lamp to Pin 2 and one to Pin 3. Connect 6 VDC to Pins 4 and 1. With the vibrator vibrating apply power to the two lamps. They should flicker alternately. Note that for this test, either use a 6 volt battery or a 6 VDC supply with both outputs not grounded. I wouldn't try to use the battery in the Jeep just in case you mis-identify which side of the line cord is grounded and which is hot.

Although a vibrator that is going to be fixed by this procedure will usually begin to work after say no more than half an hour, I have seen it take several hours. So if I have one that didn't start working fairly quickly, I'll let the test run up to about 8 hours max (or overnight) before giving up.

Robert

Gunner

USN Retired

MVPA 9480

Richard Carpenter, AA4OO, is a regular contributor to AmateurRadio.com and writes from North Carolina, USA. Contact him at [email protected].

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Snow stopped Transmission.

24 January 2021 | by Steve G1KQH | Leave a Comment (4)

This Sunday morning we have had a good dumping of snow over the Midlands area..

Around 12:00 GMT as I write this, my VHF/UHF array of antennas strapped to the side of the house are well plastered with the white stuff.

Outside Temperature is Zero Centigrade.

Steve, G1KQH, is a regular contributor to AmateurRadio.com and writes from England. Contact him at [email protected].

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