Radio Virgin: the First QSO

My first QSO (and, yeah, it was with Morse code) was petrifying and…

What’s your story of your first QSO?

73 de NW7US


Visit, subscribe: NW7US Radio Communications and Propagation YouTube Channel

LHS Episode #220: Polysyllabic

Welcome to Episode 220 of Linux in the Ham Shack. In this episode, we tackle such monumental topics as weather spotting, the ARRL Teacher's Institute open enrollment, AlaskIT.co, the EU and its stupid rules, the Open Container Initiative, HF packet, Echolink, big words and much more. Thanks for listening. Please donate to our GoFundMe campaign if you can. If you can't, please share, Share, SHARE!

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].

ICOM IC7300

Probably the best commercial radio available to radio amateurs currently is the IC7300. However, its price is still set by market forces: it could still be profitable at a much lower selling price.

Whether prices drop depends on many factors, but there is no doubt that the price is what it is largely because people are still prepared to buy at this price. If the dealers can still make a killing why would they reduce prices? Also, currently there is no real competition.

See https://icomuk.co.uk/IC-7300/Amateur_Radio_Ham_Base_Stations


Roger Lapthorn, G3XBM, is a regular contributor to AmateurRadio.com and writes from Cambridge, England.

Regulated voltage for Regenerative receiver project

Mr. Regula-tor

Building a regenerative tube receiver seems to have been a rite of passage for all hams of yesteryear.  Although I built one from a kit (4-States QRP) as my first electronics project a couple years ago I thought I'd go for the real deal and build a vacuum tube regen receiver.

I'm building a design based around the 6SN7 tube. While I'm collecting parts and still locating a suitable chassis I decided to build a regulated power supply from the parts I have.  Anyone familiar with electronics could probably whip this together in no time, but being the electronics newbie that I am, it is a slow process.

I'm using a transformer from a 1950's Heathkit VTVM V-7 that I parted out. It supplies the 6.3V filament voltage from one set of windings (yellow wires)  those tested good. But the HV was an unknown as it was only half wave rectified when the transformer was used in the meter.  That meter's rectifier and power cap had gone bad so I didn't know what condition the HV side of the transformer.

Breadboarded using a full wave rectifier created with 4 diodes, buffered by a 22uF electrolytic and a 10k resistor, I saw 189 volts, with no-load out of the high voltage side of the transformer. The amount of current the transformer could provide was still an unknown. I tested temporarily with a 2.5kOhm high wattage resistor and saw 56ma of current provided with a voltage sag down to 130V but the core of the transistor started heating up.  Within half an hour it was over 120F so I discontinued that load test.

Fortunately, the regen circuit uses a ridiculously small amount of current for B+; about 4 to 5mA. Although I will likely change the audio side of the tube to deliver enough current for a speaker rather than the high impedance headphones in the current design, which may potentially double that to 10ma.  For the first incarnation I'll stick with high-impedance headphones.

The regen power supply requirements called for [email protected] and 90V@4mA B+.  The B+ voltage  was based on using 10x 9V batteries and it stated that voltage wasn't critical but shouldn't fall much below 90V, going 12% above 90V should be OK.

Generally batteries are used with regenerative receivers because they are so sensitive to power supply noise, but I wanted to give the power supply a shot first and if it proves too noisy I can fall back to battery power for the B+ and just use the filament voltage provided by this transformer.

Since I have a OB2 voltage regulation tube I want to use. The OB2 regulates at 108V so that's what I'm going with.  An OB3 would regulate at 90V, but I don't have one of those.


OB2 in action... Glow baby, Glow!

Calculating the resistor drop

A voltage regulating tube like a OB2 ionizes gas to maintain the voltage at the tube's specification.  In the case of an OB2 it tries to maintain voltage at 108V.  It requires a starting voltage higher than what it will regulate to, but ultimately can only dissipate so much current as it drops voltage.  So, a resistor must be put in series ahead of the VR tube to limit the current it will have to dissipate.  The resistor must be able to handle the current flowing through it, so that must be calculated as well.  

The calculation for the dropping resistor resistance is:
Rdrop = (Vs - Vreg) / (Ireg + Isupply)
So, in my case:
Voltage supply (Vs) = 189V
voltage regulation (Vreg) = 108V
regulator current (Ireg) the OB2 requires 5mA to do its job = 5mA
supply current (Isupply) the actual current required by the 6SN7 up to ~ 5mA

So, (189V - 108V) / (0.005A + 0.005A)  comes out to a resistor value of  10,100 ohms.  10k is the closest standard size resistor and at 108V it should be able to dissipate 1.166 watts.  So I'll need a 10k 2-watt resistor.

Parts is parts

Running the regulated power supply with a 10k Rdrop resistor for a few hours showed the transformer stabilize at 92F degrees at 70F amb.  I was using a separate 27k 2-watt resistor to simulate the ~4mA load that the receiver will draw at 108V. 

As you can see on the newly restored, trusty Heathkit VTVM; the voltage was holding steady around 108V.  With that little current, the OB2 is not visibly glowing but with the lights out the violet colored ionization is visible.



Summary

I'm going to order a larger filter capacitor.  The only one I had to test with was 22uF 360V and I'd like to use higher capacitance value of 47uF with a more appropriate voltage rating of 250V.  I will also be adding 0.01uF caps at the input and output of the filter capacitor and I may add a 0.01uF across the OB2 pins 1/7 to further attenuate any RF noise.   

With the current values I'm seeing 50mA ripple on my regulated voltage.

A bit over 50mA ripple

After I get the new capacitor and get the 0.01uF caps in play to filter out noise, I'll hook it up to the oscilloscope to check for ripple.  I'll update the post at that time.


That's all for now....

So lower your power the old fashioned way, using a voltage regulator tube.

72/73
Richard, AA4OO

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

Weekly Propagation Summary – 2018 Apr 09 16:10 UTC

Weekly Propagation Summary (2018 Apr 09 16:10 UTC)

Here is this week’s space weather and geophysical report, issued 2018 Apr 09 0536 UTC.

Highlights of Solar and Geomagnetic Activity 02 – 08 April 2018

Solar activity was at very low levels throughout the period with only a few low level B-class flare observed on 03 Apr from Region 2703 (S08, L=193, class/area Axx/010 on 31 Mar). No Earth-directed coronal mass ejections were observed.

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit reached high levels on 02-04 Apr and at moderate levels on 05-08 Apr. The largest flux of the period was 2,150 pfu observed at 02/1915 UTC.

Geomagnetic field activity was mostly quiet with unsettled periods observed on 05 Apr. Solar wind speed began the period slightly enhanced near 470 km/s with total field around 4-5 nT. Solar wind speed declined to near 320 km/s by 04 April before increasing briefly to near 450 km/s by late on 05 Apr. Total field increased to a maximum of 9 nT at 05/2130 UTC. By 07 Apr, solar wind speed had decreased to 330-380 km/s while the total field decreased to 5 nT or less.

Forecast of Solar and Geomagnetic Activity 09 April – 05 May 2018

Solar activity is expected to be at very low levels throughout the forecast period.

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is expected to reach high levels on 12-30 Apr due to recurrent coronal hole high speed stream (CH HSS) influence.

Geomagnetic field activity is expected to be at unsettled to active levels on 10-16 Apr and again from 19-23 Apr with G1 (minor) storm levels likely on 10-11 Apr due to recurrent CH HSS effects.

Don’t forget to visit our live space weather and radio propagation web site, at: http://SunSpotWatch.com/

Live Aurora mapping is at http://aurora.sunspotwatch.com/

If you are on Twitter, please follow these two users: 1. https://Twitter.com/NW7US 2. https://Twitter.com/hfradiospacewx

Check out the stunning view of our Sun in action, as seen during the last five years with the Solar Dynamics Observatory (SDO): https://www.youtube.com/watch?v=zXN-MdoGM9g

= = = = =

BOOK SALE: Space Weather and Sun Science – get these from Amazon, and help us stay online!

NOTICE: When you buy this (or any item after starting with this link), you are helping us keep our SunSpotWatch.com and other resources “on the air” (up and running!). In other words, you are helping the entire community. So, check out this book:

Here is the link to Amazon: http://g.nw7us.us/fbssw-aSWSC

We’re on Facebook: http://NW7US.us/swhfr


Visit, subscribe: NW7US Radio Communications and Propagation YouTube Channel

LHS Episode #219: The Weekender VII

Welcome to another incredible (and we mean "in-cred-ible") edition of The Weekender. In this episode, we talk about some upcoming QSO parties for various US states, some special event stations coming up, SSTV from the ISS, NixOS, upcoming Linux and Open Source conferences, a Lowland Scotch whisky, really good ham sandwiches and drinking pine trees. All that and a lot more. Thanks for listening!

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].

630m – Winter One

Although Canadian amateurs have had the 630m band for a few years now, the arrival of U.S. amateurs on the band last fall has been a game changer in terms of activity ... it's almost like starting fresh once again, hence the "Winter One" title!


The steady arrival of new stations on the band was exciting to see and the increase in activity made nightly band-checking mandatory in order to keep up with the new arrivals. Not totally unexpected, a high percentage of the new stations were located in the eastern part of the country where ham populations are higher, giving even more incentive to watch propagation trends for those 'special' nights to put some of the new arrivals in the log.

Over the winter DX season I worked 37 'new' U.S. stations in 23 different states. Of these 23 states, 11 were on CW while 12 were on JT9. Many of the JT9 contacts could have been made on CW at the time, had that been the operating mode chosen.


Hopefully the band will see an increase in CW activity next year as activity continues to grow. It is certainly much easier to get a capable CW signal on the air than a digital one and that is what many decided to do to get a quick start, while going the transverter route was the method chosen by most.

After being active all winter, the biggest surprise for me about 630m was just how little actual power is needed to exchange coast-to-coast signals, especially when using the weak-signal digital JT9 QSO mode.

Almost every new station that I worked was running less than 100 watts of total per output (TPO). A large number of these stations were in the 20 watt TPO range which I really found astounding, considering the relatively poor efficiencies of typical backyard antenna systems on this band. Propagation, always the great equalizer, was certainly playing a major role at times and watching conditions change from night to night was an education in itself.

K9MRI - 22W / 72' vertical wire / 140' tophat (72' x -140')

K9FD/KH6 - 100W / 70' x 70' inverted-L

K0KE (CW) - 75W / 70' x 50' inverted-L

WA9CGZ - 100W / base-loaded 160m inverted-L

N1BUG - 20W / inverted-L

KC3OL - 15W / base-loaded 'T'

K8TV - 3W eirp / 55' x 150' 'T'

K9KFR - 20W / 80' wire vertical

KA7OEI (CW) - 25W / 200' circular loop at 30'

K5DOG - 16W / 275' vertical loop

KC4SIT - 60W / inverted-L
As on most bands, allowable power is limited, but on LF and MF, the limits are stated in EIRP and not TPO. Hams are limited to 5W EIRP on 630m which may not sound like much but a large number of the stations worked this winter were worked while I was running around 2-3W EIRP which often seems to be plenty when using JT9.

Although Canada's west coast is now well-represented on 630m, it would be really great to see some interest and station building from provinces to the east ... VE6, VE5, VE4 ... The fast-approaching warmer weather should provide the ideal opportunity to get any needed antenna work squared away before the next DX season begins along with its anti-antenna building winter weather!

If you are one of many amateurs that may have been contemplating some 630m work but were discouraged about antenna sizes or having to generate gobs of power, hopefully the above information will encourage you to get on the band and join the fun.

You can find more information that may be helpful in your quest via the 630m links on the right side of my blog page or by clicking here.

Steve McDonald, VE7SL, is a regular contributor to AmateurRadio.com and writes from British Columbia, Canada. Contact him at [email protected].

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