AmateurRadio.com

For those of you following this summer's regenerative receiver building adventure, I am pleased to say that all testing has now been completed. My earlier doubts about receiver-performance have now been totally resolved.

I've also published a new page on my website which contains more pictures and details of all phases of the project. The page also has a recording of the 40m CW band, made a few evenings ago, which really best demonstrates how the receiver is working.

In the meantime, much consideration has been given to the next project work ... it will be a return to my earlier lightwave experiments. During the recent visit here by Toby (VE7CNF) and Mark (VA7MM), both expressed interest in building some lightwave equipment (in fact ... 'parts' have been ordered!) to try some direct LOS work as well as to try some QRSS clear-air scatter / cloudbounce work. It's really exciting to see some new interest in this fascinating mode as the field for experimentation in both transmitting and receiving systems is quite vast.

My first task will be to build a 4" optical tube receiver or another boxed Fresnel-lens type for portable operation, here on Mayne Island, to see if I can scatter a signal to the other side of the island and detect it while operating in the field. There are a couple of nearly 600' peaks on Mayne which should provide a good shielding effect for testing ... maybe too good. Time will tell.

courtesy: http://en-ph.topographic-map.com/

It's been a few years since I have been active on 2m meteor scatter during the Perseids meteor shower. The year's largest shower peaks tomorrow night, although the peak is sufficiently broad to provide activity over several days leading up to and after the night of August 12/13.

Nowadays, using FSK441 WSJT software, a lot of good fun can be had most non-shower mornings on meteor scatter, just using random meteors. My experience when using the same software during an actual shower has been disappointing, as often the signals are too strong or too long for the software which is looking for shorter, weaker signals. During a large shower such as the Perseids, where typical burns can be quite lengthy, my own experience has given better results with good old SSB or fast CW.

I clearly recall my first-ever meteor scatter QSO, made during the May Aquarids,  back in the early 70's. I had arranged a sked with Ken, W7JRG, in Montana. I had grown up reading about Ken's VHF exploits in both QST and CQ as a teenager and was excited about the possibility of finally possibly working him. My station was homebuilt, using a 6360 transverter driven from my Heath HW-100, and feeding a homebrew 5894 amplifier with 1/4" copper tube plate lines. The amplifier produced just a shade over 100W output. My antenna, also homebrew, was a 24-foot 13 element Yagi ... probably not the best for meteor scatter although it worked well enough for me to ragchew every night with stations in Portland, Oregon on SSB.

A few minutes before our sked, I decided to make one final check of my system. Our sked was to be on SSB, using 15 second sequences. I keyed down at full-power and did a final tweaking of plate tuning and antenna loading, and unkeyed, back to receive mode after about 30 seconds of tuning up. My receiver immediately sprung to life with a very loud SSB signal, slightly off-tune. Thinking it was my local buddy, VE7BLF, calling me before the sked, I was surprised to hear a different voice ... it was Ken in Montana at S9++ ..."I've been holding my breath waiting for you to unkey there Steve ... thought you would never finish!"



Needless to say I was just as surprised as he was. We talked back and forth for about another 60 seconds before the burn finally dissipated and signals were gone. What a great introduction to meteor scatter, with the QSO completed before the sked even started! Ken later told me that of all of the meteor contacts he had made, it was one of his best ... I guess we just hit it right.

Of all the showers, I always found that the December Geminids was the best, even better than the August Perseids, at least for the North-South path. Having said that, my longest meteor contact was made during the Perseids, with Arliss W7XU in South Dakota ... just a shade over 1300 miles while running just 40W SSB to a 9el Yagi.




Good luck if you are doing some meteor scatter tomorrow or even if you are just watching the shower visually ... conditions should be ideal, if the skies are clear, as the very new moon's sliver does not rise until near dawn.

Monday was spent finishing the coil winding for my present bench project, a 3-tube regenerative receiver. The receiver first appeared in the January '33 QST article, "Rationalizing The Autodyne", by George Grammer. I tried to stay true to the original design, both physically and electrically, as much as possible. Where period components were not available, they were manufactured. Several capacitor are 're-stuffed' cases and some resistors have been physically altered to resemble era-appropriate styles. The one deviation I made from the original circuit was to remove the B+ (200VDC) from the headphones by going to impedance-coupled audio, which blocks DC from the headphone circuit. After finishing the coils and doing a quick re-check of the wiring, I held my breath and applied the power.






Much to my surprise and delight, the receiver worked immediately. It took me some time to find the correct control settings and combinations that seemed best but eventually its operation became familiar. Here are a couple of short recordings, crudely made via connecting the computer across the high-impedance headphones, as I tuned across a somewhat noisy 40m band in the evening.







Now although the receiver appears to be working, I'm not 100% convinced that it is working as well as it should. It's difficult to know exactly how it should perform when at its best as it really can't be compared to any of our modern-day receiving systems. Just what did 'good performance' sound like in 1933?

I have some reservations about one of my tubes. It's a '78' from my junk-box stash and has a large red '?' inked across the glass envelope. I may order some NOS '78's or even some more modern '6D6's, to see how they perform. On the plus side, the oscillator seems very stable and there is absolutely no 'hand-effect' on tuning, a common problem with many regens. Peaking up the RF stage tuning causes no pulling of the oscillator but the '78', although a hot-performer in 1933, provides plenty of tube noise as well, if the gain is set too high. I think the main advantage of having the tuned RF stage is to add RF selectivity and eliminate any bleed-through from some of the blowtorch shortwave signals just up the band. Tuning seems best when its gain is set between fifty and seventy-five percent of maximum. The large drum dial, in combination with the small bandspread capacitor, spreads 40m across most of the dial and makes for easy tuning although there is a small amount of backlash.

Another thing I noticed is that it seems to be very receptive to spurious computer birdies, with the laptop sitting just a foot away. Perhaps its unshielded top and bottom are the cause of this as I don't hear any of the signals on my main station receiver.

Comparing it to the two-tube regen in my Paraset, the Paraset sounds much quieter and generally sounds more sensitive ... but it uses more modern tubes, '6SK7's, first introduced in 1938, five years after the '78'. The selectivity seems as good, if not better, than the Paraset, which I consider an excellent performer. The Paraset also sounds just as good as my National SW-3, which was produced in the early 30's ... so the new regen is likely not as quiet nor as sensitive as the SW-3, probably the best simple regen of its day.

Perhaps some newer tubes will make a difference in performance and maybe my expectations are too high. In any event,  the closing paragraph of Grammer's article may be more telling that I originally thought:

"The set as it stands is not perfect, of course; nothing ever is."

Following the eggcitement of last week I am been taking it a bit easier this weekend preparing for some portable operation in Scotland.

I have made a linked dipole inspired by the ones sold by SOTAbeams, it is a simple inverted vee supported by a 9 meter fishing pole the wire elements are made of sections which are joined together depending on the band required.  I have made a two band version, 20m/40m and it tuned nicely using the analyser. 

As a backup I have also revisited the "Magitenna" which disappointed last time I tried to used it. Firstly I replaced the original wire which was too heavy for the low power I run and is very prone to kinking.


While doing this I discovered that the terminal post on "the special matching unit" was simply turning when I tried to tighten the wing nut. This pointed to a broken or at best poor internal connection and I was forced to open up plastic box to make a repair, sadly "forced" was the operative word.

One of the four screws was inexplicably super-glued in place and being cack-handed I soon ruined the head trying to remove it and had to drill it out. Once the screws were removed I then found the lid too was glued in place at several points and had to prise the lid off trying to minimise any damage in the process.

Given that nearly all other ham equipment I own is designed to be serviceable, including rigs worth several hundred pounds I found this annoying and unnecessary for a simple antenna, especially as the ethos is for amateurs to experiment and modify things. It certainly wasn't glued for weatherproofing as it would be have sealed all round, it could only have been to stop it being opened. I could understand this if it were protecting some patented, copyright design but it wasn't, behold the magic within the "special matching unit" nothing but a simple un-un which I suspected already. 



Anyway I was able to tighten up the simple screw and bolt and ironically I used some epoxy resin on the screw head to try to stop it coming loose again. Hopefully this loose terminal was the reason for the poor performance last time.

I am looking forward to having another go from operating in Scotland this year with some more experience I hope to improve on last years efforts

While tinkering in the shack I kept the FT857 on and tuned around looking to give points away for the VHF Field Day and made a number of decent DX contacts using just 30W

Following the eggcitement of last week I am been taking it a bit easier this weekend preparing for some portable operation in Scotland.

I have made a linked dipole inspired by the ones sold by SOTAbeams, it is a simple inverted vee supported by a 9 meter fishing pole the wire elements are made of sections which are joined together depending on the band required.  I have made a two band version, 20m/40m and it tuned nicely using the analyser. 

As a backup I have also revisited the "Magitenna" which disappointed last time I tried to used it. Firstly I replaced the original wire which was too heavy for the low power I run and is very prone to kinking.


While doing this I discovered that the terminal post on "the special matching unit" was simply turning when I tried to tighten the wing nut. This pointed to a broken or at best poor internal connection and I was forced to open up plastic box to make a repair, sadly "forced" was the operative word.

One of the four screws was inexplicably super-glued in place and being cack-handed I soon ruined the head trying to remove it and had to drill it out. Once the screws were removed I then found the lid too was glued in place at several points and had to prise the lid off trying to minimise any damage in the process.

Given that nearly all other ham equipment I own is designed to be serviceable, including rigs worth several hundred pounds I found this annoying and unnecessary for a simple antenna, especially as the ethos is for amateurs to experiment and modify things. It certainly wasn't glued for weatherproofing as it would be have sealed all round, it could only have been to stop it being opened. I could understand this if it were protecting some patented, copyright design but it wasn't, behold the magic within the "special matching unit" nothing but a simple un-un which I suspected already. 



Anyway I was able to tighten up the simple screw and bolt and ironically I used some epoxy resin on the screw head to try to stop it coming loose again. Hopefully this loose terminal was the reason for the poor performance last time.

I am looking forward to having another go from operating in Scotland this year with some more experience I hope to improve on last years efforts

While tinkering in the shack I kept the FT857 on and tuned around looking to give points away for the VHF Field Day and made a number of decent DX contacts using just 30W

Work has begun on a new "summer project" (as well as re-shingling the woodshed and garden shed roofs) ... a 3-tube audiodyne receiver.





This one appeared in the January 1933 addition of QST (Rationalizing the Audiodyne by George Grammer) and then in subsequent Handbooks for a few years. It's the type of building I like to do, with lots of pre-planning before breaking out the tools, measuring all components carefully and refurbishing some of the 85+ year old parts.

courtesy: arrl.org

This particular receiver has lots of metalworking involved as it uses two shielded compartments to keep the detector and RF stage from seeing each other. As well, it uses a set of ganged tuning capacitors to have the RF stage track the oscillator. The coils are wound to produce a lot of ham-band bandspread on the big drum dial... hot stuff in '33.


So far, I've completed all of the shielding and drilling of critical holes ... all measured three or four times before taking the plunge. The only chassis available (Hammond or Bud) is about 1/2" smaller in width and depth, making everything just a little snugger, but still maintaining proportions.


I have no idea how it will perform but so far it's been a fun project. If it works well, even better yet ... but handily, it's given me a good excuse to avoid more important things, like the two roof projects!

Sadly, I fear that my Tri-Tet-Ten has likely seen the last of its glory days of European 10m DX. It has been sitting, forlornly, on it's operating shelf beside my main station, for a few years now and has always been ready to spring into action whenever the winter F2 on 10m rolled-in. Although I anticipate more 10m F2 this coming fall, I don't think we'll get any barn-burner European openings as I have seen in the past. Conditions really need to be very good for the 6L6's 4 1/2 watts of 10m output to make it over the pole but over the past four winters, the one-lunger has worked over 100 Europeans on 10m F2.

Not being quite ready to throw in the towel on one of my favorite ever projects, over the past two nights I have sparked-up the tritet on 20m, which has been like the good old days in the evening ... strong signals over the pole peaking around 2130 local time.

As it did on 10m, the tritet did not disappoint! My first CQ (crystal controlled on 14031 kHz) was a pounced upon by two Europeans, eager to work a VE7. Over the two evenings, contacts were enjoyed with the following stations:

OE5FBL  Haid, Austria
RV3LK   Smolensk, Russia
UA2FT   Polessk, Russia
RA2FAC   Kaliningrad, Russia
RA1OD   Kotlas, Russia
R3RR   Tambov, Russia
DL1SXB   Schwerin, Germany
UR5LCZ   Pivdenne, Ukraine
MD0CCE   Ramsey, Isle of Man
OK1KTI   Huntirov, Czech Republic
IK1XPP   Crescentino, Italy

All of the stations were worked on my crystal frequency (a very old 40m xtal doubling to 20m) of 14031 kHz and answered my CQ. At just under 10 watts output, the average signal report received was 579.

Interestingly, two stations gave me 'T' reports of less than 9 to (incorrectly) describe the slight chirp on the oscillator. In the RST system, anything less than a 'T9' should actually describe the degree of undesired modulation (usually A.C. ripple) and not chirp. The proper way of indicating chirp is to append the report with a 'C'. Since chirp is rarely heard on the airwaves anymore, it's understandable that some might not properly understand the 'T' part of 'RST'.

So it looks as though the Tri-Tet-Ten has earned the right to stay on the side operating shelf a bit longer ... but I'm not renaming it the 'Tri-Tet-Twenty' just yet!