Space Spanner Success Story

I picked up this Knight Space Spanner several years ago in non-working condition. I have an entire shack full of non-working project radios. Actually, more than I have working radios. It’s a simple tube regenerative AM receiver with a selectable band for broadcast or shortwave. Think of Knight radio as the do it yourself branch of Allied Radio back in the day. They produced a wide array of radio kits for the consumer market. This model was produced from 1956-1964. It’s not great as far as receivers go. Even back in the day there were much better offerings available, but I’m guessing this was aimed more at the general radio listener than hams.

The regen is a funny beast with a history that goes way back to the early 1900’s. Tuning in a station is a balancing act between volume, regeneration, antenna coupling, and dial setting. Any mis-adjustment of any combination of these switches results in useless noise or screaming oscillations. The screaming oscillations are the worst! It might be wise to offer up a solid state electrical device as a sacrifice or recite ancient incantations prior to resurrecting one of these demons. But when proper tuned, a station does sound surprisingly nice. I’ve found it quite pleasant to listen to local oldies radio on the AM broadcast dial.

What it lacks in features it makes up in simplicity. Not a lot going on inside this small box. The schematic is simple to follow and the circuit is all point to point wiring. I’m sure it would’ve been an entry level project when new. Back then you had to be tough, though. There’s no transformer isolated HV power supply. All the tubes are lit in a series string straight across the wall line voltage. Insert the non-polarized plug in the socket backwards and you’ll get AC voltage on the chassis. I guess folks were just supposed to know better than to do that more than once! What I’ll refer to as a self-correcting error.

I’m preparing to rebuild a Hallicrafters SX-28 this year. That’s way above my current skill level and I need more practice. This Space Spanner seemed like the ideal candidate. It already didn’t work so I figured I couldn’t make it any more broken! I had to go at it in small spurts due to my busy work schedule. Overall, it’s been quite rewarding to make it play again.

Crusty old parts removed from under the chassis

It didn’t have any tubes so I started with ordering them from the web. Tried it out, but no love. I then removed the aged electrolytics. There were only three, and plenty of room to work. I also found a suspect ceracap. I don’t know anything about them, but replaced anyway. There’s a cap straight across the neutral to ground. I believe these are called a “death cap”. That was replaced with a proper XY AC-rated safety cap. Powered it up slow on a variac, hooked up an antenna, no smoke, and…no love! Not really even much noise.

View under chassis before surgery
New caps don’t take up nearly as much space

Well, it took me a long time to get back to the radio again. This time I printed off the schematic and started tracing it line by line. I finally came across a mis-wired ceramic cap. I did nothing more than move it from one point on the terminal tie strip to the spot right next to it. This time it worked straight away! How awesome a feeling to bring it back from the dead! I wonder if it ever worked, or who mis-wired it. I also found an extra wire tack soldered that was removed during the repairs. I wonder what it was for. Repairing old radios is often a mystery.

This little ceramic cap from tube socket pin 7 to terminal tie strip is the culprit. Should’ve been landed on the first tie point.

I always seem to learn something new after each repair. Each case is unique and I rarely turn up a unicorn that work perfectly straight away, have never been touched by human hands since construction. I guess I’m about up to 1960’s skill level. With any luck I’ll progress to the 21st century by the time I retire! Maybe not, old radios have more soul than modern stuff. I’m glad to keep another piece of history from the landfill.

Categories: Uncategorized | Tags: , , | 1 Comment


Hello again.  I felt like it was time to update the radio deals.  Some stuff has sold, some has finally gotten cleaned up.  I’ll try to keep adding as I go.  I don’t have pics for everything as there’s still a lot in my shack back home in Indiana.  I’m going to add some cool vintage gear I’ve never had time to fully troubleshoot and repair.  Nonetheless, I’d still like to move it at a discount if there are some enterprising radio techs out there that need a project.  I’m hoping to make some local deals to avoid the high shipping costs.  Looking for buyers back home in the Indianapolis area or near my new QTH of Campbellsville, KY.  I’m not really sure how far this website reaches.

All the usual caveats of buying used gear apply.  You can see it before you buy and anything is worth what someone is willing to pay…so I may flex on the price to make a deal.  It just depends on the item and whether I’ve got it fully cleaned and tested.  If nothing else, enjoy checking out some stuff!


ETO Alpha 99 legal limit linear amplifier.  Tear down and clean up has finally begun.  $2000



Yaesu FTdx-560 all tube transceiver with matching mic and FV-401 ext VFO.  Early ’70s vintage.  Semi-working.  Ask me for details!  $200


Yaesu FRdx-400 all tube receiver with matching speaker.  Early ’70s vintage.  Receive is dead.  Last used during 2018 AM QSO party.  $100

This is a stock photo for reference


That’s all for now.  Hope you see something interesting.  Best way to contact me is by email (I’m good on  Sales benefit the wife of an SK who was my elmer…I have no personal stake in any of this.  Thanks for taking the time to look.  73 de n9iz

Categories: Activities, Amateur Radio, News | Tags: , , | Leave a comment


As mentioned in the preceding post…I have a lot of radio gear to sell.  This is the first installment with just basic pics and description.  I’m hoping to make some local deals to avoid the high shipping costs.  Looking for buyers back home in the Indianapolis area or near my new QTH of Campbellsville, KY.

All the usual caveats of buying used gear apply.  You can see it before you buy and anything is worth what someone is willing to pay…so I may flex on the price to make a deal.  It just depends on the item and whether I’ve got it fully cleaned and tested.  If nothing else, enjoy checking out some stuff!


Yaesu MMB-60 quick release bracket for many older Yaesu radios 10 dollars



Sounds Sweet communications speaker (no longer in production) 40 dollars



ETO Alpha 99 legal limit linear amplifier (not yet fully cleaned and tested) 2000 dollars



Icom V8000 high power 2m FM transceiver (not yet fully cleaned/tested) 100 dollars

no pic yet


Yaesu VX-170 2m FM HT plus all accessories (battery dead, TX only only on low power) 50 dollars



That’s all for now.  Hope you see something interesting.  The best way to contact me is by email (I’m good on  These sales benefit the wife of an SK who was my elmer…I have no personal stake in any of this.  Thanks for taking the time to look.  73 de n9iz

Categories: Activities, Amateur Radio, News | Tags: , | Leave a comment


The shack is in a state of flux again. It’s just about reached the maximum carrying capacity dictated by the fixed volume of my 8X16 mini barn/radio shack. This seems to happen once or twice a year. Every time I clean it up and get rid of the excess it seems to fill back up with new acquisitions. It’s like there’s a constant mass that must be maintained.

Been away from posting anything for awhile. Work was just too busy and other competing responsibilities vying for my time. Lately, I’ve been living away from home in Kentucky. I left my old job where I’ve been off and on since 1999. Getting mostly settled into the new routine now. Fortunately, I have a rental house down there and a spare room. I’ve turned the rental into a radio gear annex to free up some space back home. Nice to have a spare bedroom and a small table for a work bench.

I have an ever-growing list of items to offer up for sale. I’ve completely dismantled the station of my elmer, Steve W9RO, who is now an SK. His son wanted some of the station but there’s still a lot to sell for his wife. It’s fun to play with some of the stuff and dig through it all. Gives me something to do while I’m away from home! Ultimately, it all must go. A lot of the items are listed on Free Classified Ads. I’ve had pretty good success using them over the years. The shipping is killer on the heavier items, though. I’m going to experiment with just posting pics and descriptions here on my blog page. Maybe some of my friend or local hams will see something they like and we can make a deal. Hopefully, I can also make some connections with the hams down at my new QTH. Going to see if I can get the items listed on their weekly swap net.

Stay tuned for more. Hope to get back into the hobby again. Still lots of fun stuff to do and try. I’ve already make more HF contacts in the last couple months than I’ve had in the last few years. Hoping this jump starts me again and I can make some new friends down here in KY. 73 for now!

Categories: Activities, Amateur Radio | Tags: , | Leave a comment


I’ve been doing a bit of AM operating of late.  This vintage mode if fun to operate and sounds great when the band conditions aren’t too noisy.  I’ve also been repairing and tinkering with some old transmitters as mentioned in other posts.  One of the highest pursuits of the AM op is to achieve great audio.  Many will go to great lengths to buy studio rack gear with pre-amps, compressors, limiters, and EQ.  Top off all this hamsexy rack gear with a big old boom mic!

The other part of the equation is to properly adjust the audio modulation.  It’s not as simple as watching the ALC meter like on SSB (although it does help).  A first step is to look at the RF waveform on an oscilloscope.  You want to verify that the wave isn’t flat topping.  A modulation monitor can be used to view the modulation percentage.  Combine these two together and you get the AMM-SD1 by Radio Engineering Associates.  This slick device connects into the feedline and runs in software on the computer.  It’s pretty much real-time display shows the RF waveform and the negative and positive modulation percentage peaks.

Seemed like this might be a worthwhile investment for the shack…like I even need an excuse to by cool shack gear!  So far it’s confirmed that my AM audio is clean with positive peaks over 120% and negative peaks right at 100%.  Right about where it needs to be.  I’ve also used it to detect that the Ranger II I’m working on is in need of further inspection.  The positive peaks only hit about 40% before the stopping point when negative peaks hit 100%.  I never would have found that without the monitor unless trying to make a contact and some OM tells me my signal is crap.

This monitor has already proven to be an asset to my radio operation.  I just wanted to share it with my followers and encourage people to give AM a try if you like a little more than UR 59 OM, QRZ.  There are frequent AM operating events throughout the year, so there’s no excuse not to lay down some carrier and chat it up.

Categories: Activities, Amateur Radio, Projects, Uncategorized | Tags: , , , , , , | Leave a comment


I’ve been taking a bit of a break on the Viking II project I mentioned in the last post.  Multiple projects always seem to make their way into the shack and cause me distraction.  I had an offer come up I couldn’t refuse, and so, had to make room on the bench.  My friend Ward K8FD has four Johnson Viking Rangers in his collection.  Two are the original model Ranger and the other two are Range II models.  He wants to have the best one of each model repaired and keep it for himself.  I get to keep the other two for my collection as payment for making all the appropriate repairs.  Sounded like a good deal to me.  Fortunately, Ward already purchased a couple nice capacitor repair kits and some missing hardware from Nationwide Radio and Equipment Sales.

The new parts are quite a bit smaller than the original parts so it wasn’t too much trouble fitting them into the chassis.  Several of the old caps were pretty crusty and would certainly would be an issue if they hadn’t already failed.  I didn’t want to take any chances so I went straight to making repairs instead of giving an initial test.  Along the way, I also tested the tubes and found a couple bad and wrong spec.  I was able to do a swap-a-roo since there were four transmitters in the shack!

Repairs have been pretty straight forward so far.  Considering it didn’t work at all when I started, making even a little power is success.  Power output stays around 25-30 watts AM and CW.  I’ve found it to be pretty easy to tune up compared to other tube rigs I’ve tried.  It also seems to be pretty forgiving and tolerant of my slow tune-up, which is nice…I have smoked components before from persistent mis-tuned conditions.

This is actually a 160-6m transmitter which is kinda cool for such an old rig.  I suspect most people really only operate them on 80 and 40m if running AM.  Maybe other bands on CW I suppose.  The dial reads within about 12 kHz which isn’t too bad.  Looking forward to installing it back into the cabinet and giving it a try on the air.

Categories: Activities, Amateur Radio, Projects | Tags: , , , , , , | Leave a comment


IMAG1621The first stage of fixing up this old transmitter is disassembly.  When Johnson built their gear they certainly didn’t spare the fasteners.  This thing is held together by a ton of slotted head screws.  Took forever to remove them all.  Fortunately, the cabinet came apart really easy.  The hardest part was removing the front


face.  Once I had all the pieces separated I got busy with a bottle of Formula 409 cleaner and paper towels.  This works pretty well on most stuff.  I also used a tooth brush to really scrub the parts that had a course exterior finish.  It didn’t work miracles, but for a transmitter nearing 70 yrs old it’s not too bad.

IMAG1643I now have access to the chassis of the beast.  I’m impressed with the overall design, construction, layout, and quality.  You can really tell these were built to last.  The top side will definitely need some scrubbing, but I don’t see rust or corrosion.  Of specific interest is the ganged, gear-driven variable inductor/capacitor tuning unit.  Not only is it exceedingly grungy, but it’s not operating correctly.  I believe this is the only item of concern up top.

IMAG1644                                  IMAG1645

The bottom of the chassis also looks as expected.  A little dusty and some spider webs, but pretty clean.  Fortunately, no surprises down there.  I will have many electrolytic and waxy caps that will need replaced.  Since I don’t own a leakage tester I’ll just have to assume they’re all suspect at this age.  The worst thing is to let electronics just sit.  Even very old components will continue to perform for decades if they’re just used regularly.  IMAG1618I’ll also have to do some checks on the resistors as they’ve probably drifted, too.  Some components are more critical than others depending on the particular circuit.  This will just take some time to research the usual suspects and start ordering.


Fortunately, Johnson made a lot of these transmitters.  I’d like to purchase a manual reprint but was able to easily find a PDF on the BAMA website.  I’ve found them to be very helpful for everything except Heathkit (because of copyright licensing).  I’ve had good luck purchasing reprints from Manualman and others.

IMAG1620Here’s a pic of this big honkin’ oil filled cap.  No reason to include it except it’s cool.  Just another example of the quality put into these rigs.  Hoping to get the chassis all cleaned up and the roller inductor functional again.  That will complete the first phase of the project.  I think the next part will be more fun.  I like working with components better than cleaning stuff up.  Stay tuned.

Categories: Activities, Amateur Radio, Projects, Viking II | Tags: , , , , , , | 1 Comment



Most hams who know me, know that I love to tinker and work on projects.  Sometimes they even work out in the end.  So begins this one.  I’m an avid follower of the Soldersmoke podcast and website.  Bill Meara N2CQR and Pete Juliano N6QW host a monthly podcast all about QRP and radio homebrew.  Their inspiration has given me the courage to begin and successfully complete several projects.  The Michigan Mighty Mite is a good example.  One of their homebrew heroes is Ashhar Farhan VU2ESE who invented the BITX transceiver 14 years ago.  Last year they reported that he’s selling the board fully constructed and tested.  All you need to do is find a suitable enclosure and attach the peripherals.  At the $45 price point it’s hard to beat as a development platform.  The basic radio can be upgraded to stabilize the analog VFO or even improved by adding a DDS or PLL VFO quite easily.  Low pass output filters can be added to take it from a 40m monobander to all band operation.  I couldn’t resist!

IMAG1638With the circuit fully complete, this amounted to a one day project to get the basic assembly done.  I found a suitable Christmas tin for a cabinet.  The majority of my time was spent laying out and marking holes for the board standoffs and all the jacks and pots to be connected.  It’s not exceedingly elegant but I IMAG1639was able to accomplish it all with a hand drill, pliars, and a couple wrenches.  I chose the metal enclosure because I thought It might provide good shielding.  Eventually I’ll probably add a small fan and punch some holes for ventilation.  There should also be enough room to add an Arduino, DDS or PLL board, and cool LCD display.  I think it would make a perfect radio for portable operation with a battery and 40m dipole at the park.


I wanted to include a couple shots of the innards.  Everything came included with the kit, including the wiring pigtails to attach to the board headers.  Pretty straight forward assembly.  The HF Signals webpage has all the technical info, assembly

IMAG1641instructions, reference materials, and purchase info.  The product is sourced and shipped out of India and constructed by a local women’s collective that helps provide skills and jobs.  They typically arrive in less than a month.  Not bad turn around time.  Easy ordering with Paypal.

So here it is with a couple knobs out of the junk drawer.  I trialed it on the bench and it plays great, minus the drift.  Even that settles down after about 15 minutes.  Crisp, clear analog audio…but you have to ride the AF gain what for having no AGC.  I bet you could probably hack that into the circuit pretty easy, too.  I could generally hear just about anything I could copy on the Flex-5000, so that says something about the sensitivity.  This was a fun and functional one day project with only minimal soldering required.  Looking forward to doing some more hacking on this one!  Will try to produce a companion post with a little video production for everyone playing along at home.  73 all.


Categories: Activities, Amateur Radio, Projects | Tags: , , , , , | Leave a comment


It appears as though I haven’t made a post in over a year.  Time flies when you’re having fun…or extremely busy.  It’s time to start a new project.  In doing so, it might be fun to document the progress here in cyberspace (does anyone even still say that).  It’s a good way to keep track of what’s been done, and also share with friends.  Often times it might also be a topic of interest to many others outside your local chums.  My posts on the ARD 230 project sure generated a lot of feedback from other owners.  I received inquiries from hams as far as Spain and Germany!  Strap in for the ride…here it begins.

IMAG1421I got energized to try something new after participation in the AM Rally early this spring.  I’ve always been interested in vintage radio and the roots of our hobby.  While CW holds the crown as oldest mode, AM isn’t too far behind.  Many modern and vintage radios will operate AM, but I get a kick out of using vintage gear to operate a vintage mode.  My lash-up for the event was a Heathkit DX-60A transmitter with the matching HG-10 VFO and Astatic D-104 mic.  Classic 60’s and good for about 55W PEP.  The receIMAG1354iver was a Yaesu FRdx-400.  Early 70’s production, and it did pretty well for me, too.  I didn’t yet have a dowkey relay so all the switching was done manually.  Let me tell you, that’s a lot of work just to complete an exchange!  My time was limited, and I made only one contact but I think the hook was set.  Time to finally breath new life into this old gear that’s been sitting around cluttering up my shack.

TeJohnson-logo-1n years ago I purchased a Johnson Viking II transmitter from a good friend and elmer Joel, K2LYC (now SK).  I also came home with several other vintage pieces from his extensive collection, but that will become the subject matter of many future posts.  The intent was to setup an AM station (Studio B) to accompany my then-modern Icom IC-756 station (Studio A).  Somehow a decade passed away and, sadly, so did Joel.  I guess I feel like I owe it to him to get this stuff playing again.  So, it begins with the transmitter.  I’m going to start there because usually they’re simpler.  I’ve also had pretty good success fixing others.  Fortunately, there’s loads of info available at my fingertips.  This is the intro so I’m not going too deep.  My plan is to remove the chassis from the cabinet for overall cleaning and inspection.  I’ll replace any faulty components and perform only the mods that are proven and considered best practice.  No total restoration needed.  I’m sure every scratch and scrape tells a story.  It’ll never be a mint specimen, just an honest workhorse.  Eventually it’ll pair with my Collins 75A-3 (which will probably be the next project).  But you see I’m already ahead of myself.  Next post will start getting into the real heart of the job.  73!IMAG1621

Categories: Activities, Amateur Radio, Projects, Viking II | Tags: , , , , , , , | Leave a comment



After Flex Radio’s newest Signature series software defined radios hit the market there’s been a steady decline in value and interest in their original Flex series radios (Flex-5000, 3000, 1500).  The only one still marketed is the Flex-1500, and only time will tell how much longer it will last.  Flex now refers to these radios as their “legacy” series of radios and unfortunately has ceased developing software for them as well.  To the best of my knowledge the Flex-1000 was their first radio and is considered first generation SDR technology as it required a soundcard interface with the computer.


In spite of the excellent performance of the newest generation of SDRs on the market there still remains a dedicated core group of Flexers using their “legacy” radios.  Recently I’ve found a bit of good news for those who haven’t yet jumped ship to the current offerings available from Apache Labs or Flex Radio.  Darrin Kohn KE9NS has been developing an independent version of PowerSDR Ver. 2.7.2.  He has an entire page on his website devoted to his Flex-5000A and all items relevant to its operation.  I’ve heard rumor of one other ham doing a bit of software development, but Darrin’s is the best I’ve seen so far.  His improvements have been well done and easy to implement.  The upgrade is as easy as downloading the PowerSDR.exe zip file from his webpage and extracting it.  Rename the PowerSDR.exe file that currently resides on your local machine to something like PowerSDRbak.  You’ll also need to rename the config file as well since the latest version also upgrades the config file.  Drop this new file in the same folder where your current files reside.  It loads up without issues.  Darrin does recommend exporting the database just in case, but I haven’t experienced any issues.  The new file doesn’t change anything in the database.  He has the instructions on his Flex webpage as well.


This also makes all these older Flex radios on the market more of a value.  Current prices are very low compared to their original purchase price.  Mine was purchased in 2010 with a $100 “Dayton Discount” for $3100 which included the wide range antenna tuner, but without the second receiver.  I could probably buy one better than mine for half that now.  And performance is still on par with just about any current model offered by the mainstream manufactures.  Sherwood Engineering still ranks the Flex-5000A in the top ten based on receiver performance.


So far Flex Radio has been willing to work with independent developers like Darrin.  Their source code is available, but requires an email request.  In a recent correspondence with Tim Ellison W4TME, Customer Experience Manager of Flex, he directly told me that they encourage independent development of PowerSDR and see it as the primary reason many hams get involved in the hobby.  I sincerely hope that’s the case as they haven’t been apologetic in saying that they are done with developing the software and compare it to the depreciation of PCs as folks upgrade every few years when they get old.  In reality, the reason I purchased an SDR in the first place was the hope that as times change, so would the software.  Meaning that my radio wouldn’t be defined like the traditional knob and button rigs, but always evolving.  Now I sometimes wonder if we’re just one MS Windows OS away from failure.  At any rate, my station is running great on a Win 10 machine with one of Darrin’s custom versions so far.


The developers at HPSDR are doing a great job with their version of PowerSDR as well.  It’s actually based on older source code, but they have been able to implement some great features.  Two of which are CESSB and PureSignal active pre-distortion.  The CESSB cleans up the audio on the mic side of the rig and actually results in higher average power output.  PureSignal cleans up the output side generating a signal with much lower IMD and harmonic suppression.  Hopefully some of the features can be shared between these two.  For now I’m glad that there are hams like Darrin who continue to develop PowerSDR for legacy Flex radios such as my Flex-5000A.  He’s currently up to Ver. 2.7.2 R12.


Categories: Amateur Radio, Computers/Software | Tags: , , , , , , , | 2 Comments

Blog at