Frequently Asked Questions - about vintage tube-type ham radio and communications equipment

Keywords: vintage radio, ham radio, vacuum tubes, boatanchors, FAQ

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Created and maintained by Nick England K4NYW.
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BE CAREFUL - Boatanchors are heavy and contain lethal voltages !!

What are Boatanchors?

Big....Heavy....Old....Fun !

"Boatanchor" is a fond term for vintage tube-type ham radio and communications gear. Manufacturers like Hallicrafters, Hammarlund, National, Johnson, RME, Heath, Collins, etc.made this gear through the mid 1960's. Also included is tube-type military radio gear, homebrew gear, station accessories like microphones and keys, and test equipment of that period.

Why Boatanchors ?

by John Brewer WB5OAU

Some may question the desire for 80 pound receivers and 100 pound transmitters, both with filaments sitting there getting hot and wasting power in this day of microprocessor based, mega-memoried miniaturized transceivers! Although modern radios are extremely good at what they are designed to do, they are about as interesting to operate as a toaster oven. They have no soul.

Additionally, many find a zen-like feeling in taking an old, misused ratty old radio and carefully restoring it back to health. Like cars of the era, boatanchor radios were made to be worked on, modified, and tinkered with. Many think of it as Real Radio in this era where fixing a transceiver is accomplished by boxing it up to send to the manufacturer for a custom VLSI chip replacement. Indeed, a warm soldering iron is almost a requirement for operating a vintage station.

Others claim that boatanchors SOUND better than their silicon descendents, and this is generally true. The audio from a Hammarlund or National receiver, or a Johnson transmitter can sound much better than the 300mW audio coming out of the 2" speaker in the typical transceiver.

Watching the flicker of 807 modulators in a Viking I as you speak into a D104 mic, is certainly more stirring on a winter night than considering hole and electron flow.

If truth be known, much, if not all of the above, although true, are merely justification for the insatiable hunt for more and more of these old boxes, simply because they are just too NEAT to have and operate!

How can I read articles?

Most any web browser will also allow you to read newsgroups. Use that function to read the newsgroup where people post discussion, info, wanted, and for-sale articles. should work OK

What is the newsgroup for?

The polite discussion of boatanchor related topics:

Who is welcome on the newsgroup?

What is newsgroup NOT for ?

Where can I find out more about Boatanchors?


This site is a member of the Boatanchors WebRing.
To browse visit Here.

Where can I find Boatanchors on the air ? - click here for a list of nets

How can I practice Safe Boatanchoring ?

This is a genuine concern! Boatanchors have Real Voltage present in them! Lethal voltages!
You will find that capacitors really DO store charge! None of this wimpy 12 volt stuff!

Get back in the habit of discharging any capacitors that are lurking under the hood. Keep one hand in your pocket when working on a hot radio. Be REAL careful and THINK THINK THINK before twiddling with a boatanchor that must be powered up and worked on.

It is SO easy to get used to working on solid state equipment and not worrying about Real Voltages... don't do this!

BE CAREFUL - Boatanchors are heavy and contain lethal voltages !!

Also, many older radios are not fused... receivers are good examples of these. I generally replace the line cord (they usually need it anyway) and either put an in-line fuseholder, or some of the Heath-type fused plugs in the radio. Better still, replace the 2-wire plugs with a more modern 3 wire plug. Barring that, ensure that you strap every cabinet with healthy sized cable to a common station ground. This will prevent you from becoming the cable between two pieces of gear at different cabinet potentials.

Fires are nice to have burning on winter evenings but not when they are on top of your operating desk.

Speaking of operating desks, you will become good at carpentry if you spend much time as a boatanchor operator. You will quickly discover that the table you used to operate your tranceiver is way too small, and waaayyyy too wimpy to support a growing boatanchor station!

How do I restore a Boatanchor ?

by John Brewer WB5OAU

This subject could easily fill many pages.
There is a lot of really good info from Hank Van Cleef in the FAQ:

Below are just some common topics.
The newsgroup is a good place to ask about other issues. Remember the radio that stares at you from your bench is old. There are not many around. Take that into consideration as you proceed through the process. If you erase the dial marking on your receiver by cleaning it with Windex, you likely will not find another at Radio Shack. Take your time and enjoy. The journey to a working boatanchor, like life, is the _point_ not a process. You will say less nasty words if you take your time.

Some general restoration tips:

"Rethinking Re-capping" from Dave AB5S, a very experienced vintage military equipment restorer -

Concerning the restoration of historically-significant radios: my views and goals have evolved over the years.  My goal- personal fulfillment from answering the challenge of these sets aside- is to give the radios the best chance to be preserved beyond my time as their temporary care-taker.  To do so, I believe the radios must play, and should do so with the minimum disturbance of the original assembly possible.
There was a time when I would say "replace every electrolytic and every paper and every Micamold" as a matter of course.  I no longer do that.  Been working on a set of three RAX receivers that have been awaiting their turn in my barn and storage, for at least 12-15 years.  All have been playing 12-24 hours now without failure.  One needed no cap replacements at all.  The second needed one and the third needed two.  I changed no resistors. Did repair some bad trimmer caps in two receivers, but not counting them for this post; different issue.  To find those that actually need to be changed requires a reliable schematic, a good meter, a variable B+ supply, patience and a finger tip.
In a tube type receiver such as the TCS, SCR-274N, or RAX, there are several paths that B+ travels to ground.  Most of them go through tubes.  When the tubes have no filament voltage, the tube plate or screen pin is a "dead end;" an open circuit.  No current should flow through the tube's plate or screen circuits. But there are usually other paths- like screen-voltage dividers- that provide a path for some current flow.
If you spend some time with the schematic, you can trace all the B+ distribution busses, looking for paths to ground.  For instance- in the -274N receiver, two 7000-Ohm resistors are connected between B+ and ground as a screen-voltage divider. With the tube filaments off, the receiver out of the rack and with no local control box installed, the only path for B+ to ground is through those two resistors, unless there are leaky bypass caps. So, with no filament voltage, if we connect our variable V+ supply and increase to 100V, we should observe no more than  100/14,000= 7 milliamps of current flowing.  If we have more, we have leaky capacitors somewhere.
So how do we find the leaky cap(s)?  Did this test on one of the RAX receivers.  After allowing "reforming" time for the electrolytic caps (and no filament voltage), at 100V on the buss, it was drawing 20mA.  100V was dropping somewhere and at 20mA, the leak was turning that current into 2 Watts of heat.  That doesn't sound like much, but it builds-up quickly.  After a few minutes, a finger-tip on one of the .05 uFd screen bypass caps felt the heat and the ZM-11 proved it was the villain.  After replacing that cap, the current on the B+ buss dropped to 6 mA; just 2 mA above that expected and close enough to operate.  Left the 100V on the buss for four hours and no increase in the current.  That's not a promise no other cap will fail- they are 70 years old.  But if the goal is to do the least possible and given I'll be running these at reduced B+, the risk of damage is small and acceptable.  If one can't "feel the heat," a study of the B+ distribution on the schematic will reveal places one can lift a wire or part to isolate the branch with the bad actor.
In many radios (not in RAX but in others), there are coupling caps that go to grids which can be leaky.  Apply B+ with no filament voltage as before.  Measure the grid of the tube fed by the capacitor coupling.  If you have a positive voltage on that grid with no filament voltage, change the coupling cap.  NOTE: Use a VOM for this, not a VTVM.  The very-high input impedance of the VTVM may be "spoofed" by an electro-static charge on the grid side of the capacitor plate.  A good VOM will load it just enough to give you a "real" reading.  Exception:  Leaky cathode bypasses, especially the one at the Audio PA, need to be checked individually, since there's no current path to find them without filament voltage.  Quick check:  Calculate the current that should flow through the cathode resistor if you put +10V on the tube cathode.  i.e. if the cathode resistor is 330 Ohms and you connect +10V to ground to the cathode, you should see 30 mA of current flow.  If (after a reasonable "reform" time) it's pulling more than 30 mA, your cathode bypass is leaking.
But what about OPEN bypass or coupling caps?  With the danger of frying things from bad bypasses and coupling caps past, one can power the set and check performance.  If you have open bypasses or coupling caps, *the circuits will tell you.* Oscillation in IF amps or Converters usually equals open bypasses.  A screwdriver touched at tube bases will often change the "motorboating" and tell you which stage is oscillating, or use a scope.  If the oscillation changes with tuning, the Mixer/Converter stage is oscillating (this happened with one of the RAX receivers- open cathode bypass on the Converter).  If the audio is distorted, look for open bypasses in the 1st Audio and Audio PA.  If you have no gain through a stage, check any coupling caps that might be involved.   But we shouldn't assume in these cases that capacitors are the culprit; resistance and voltage chart checks are your friends.  For instance- I've revived three TCS receivers lately and I find wonky resistors to be an even bigger problem than capacitors.
With these techniques, I have three RAX receivers on the bench playing nicely for hours.  I've changed three capacitors, no resistors and one tube.  

It is a poor job that doesn't require at least one new tool !
Wrenches for knurled nuts - 
GC Electronics 9358 (1/2") and 9359 (5/8") 

Here is some older info -

Helpful Hole-filling Info from Ken Ketner

JB WELD works wonders with just about any kind of ding or unwanted hole
in cabinets.  I have filled 1/2 inch holes in the grilled cabinet tops
on Heathkits, Hallis, etc.  You will have to repaint. Here is my

Clean up the hole down to bare metal, and be sure you have smoothed any
ragged edges. Inside, place scotch tape or similar clear tape to cover
the hole on the inside. From the outside, carefully work in sufficient
JB WELD to overlap the hole edges and leave a bit of a crown on the top.
A crown on the bottom side is good too. Be sure that you have a crown on
the top side as the stuff starts to set. Placing a desk lamp down on the
JB WELD helps it to cure solidly. Once it is really well set - about 24
hours, peel off the inside tape, carefully sand both sides down to flush
with the metal to get a good paintable surface free of scratches. This
can be achieved by going through the grits as you sand down the crowns.
I was able to re-drill the screen grill holes in my patched cabinet
using an X-axto knife to start the holes in the JB, then drilling slowly
with a pinvise (a little hand drill).

These patches take paint well. I have also had some of these JB repaired
cabinets powder coated (see
). Powder coating involves baking the finish at 400 F. The patched
powder coated cabinets came out flawless.

Ken Ketner

Restoration Info on the WWW

Commercial restoration & repair: (also see ads in Electric Radio Magazine)

Where can I get a manual ? - Click here for a large list of sources

Aren't tubes and parts impossible to find ?

Nope - there are lots of tube dealers attending hamfests and antique radio swap meets, and selling via mail order. Besides, there are lots of 50 year old tubes out there working just fine.

Fortunately, hams are notorious packrats and parts suprisingly abound, for old gear, particularly at hamfests (and in the boxes under the table as mentioned earlier). Word of mouth once again will work wonders at getting tubes, high voltage caps, and the like shoved in your direction. Beware that this is an addiction, and boatanchor radios, parts, and periodicals will soon overrun all available space. Trust me.

Where can I get tubes & parts ? - Click here for a large list of sources

What type of Boatanchor should I get?

by John Brewer WB5OAU

This is a question that has as many answers as there are individuals. Generally, as a "starter" boatanchor, 50's vintage gear is probably the best way to go. Radios in this era are quite desirable, but often times won't require extensive surgery to get repaired and on the air. A radio from a well-known manufacturer is also a good choice... for receivers, look for Collins, Hammarlund, Hallicrafters, and National are all good radios. In the transmitter space, Collins, E.F. Johnson, and Heathkit (with certain reservations) will do well.

Transmitters with plate modulated AM are the more desirable units. Prices will generally reflect this.

Good "starter" transmitters include, but are not limited to:

"starter" receivers include:

By "starter" radio, I do not mean to indicate the cheapest! Most of these radios would also be on the "best" list. I selected these as they _are_ some of the best, and when one is starting anything, it is good to get the BEST stuff available, rather than getting junk and getting discouraged with it. There will be enough to learn (or remember!) without having to compensate for marginal equipment (was that 'Peak the plate and dip the grid, or the other way around??')! Any radio from this list will do the job for some time, and make operating a pleasure.

What do they cost ?

It all depends on condition, collectibility, rarity, how desparate you are, etc. Look at old postings on via DejaNews. Also take a look at Bry's Boneyard Price Guide to see what typical asking prices are. Good Luck!

Where can I find Boatanchors for sale? - Click here for a list of sources

The best way to find a boatanchor is to let other hams in your area know you are interested in them. Often times I have been given a boatanchor, because the former owner has relegated it to the garage or basement. This is also the cheapest method.

When attending a hamfest, ask some of the sellers if they have any vintage gear for sale. Often times sellers won't bring such stuff, as it is HEAVY and is perceived as not being sellable. Look under the tables, and in the back of the sellers displays for them! While you are under the tables rummage thru the boxes of parts found under there for parts that will come in handy restoring your new-old treasure. Tubes, high voltage caps, vintage microphones and connectors may be found lurking here!

If you are in a hurry (and have money) ads in Electric Radio magazine, the Ham Trader Yellow Sheets, or your local packet BBS are good places to look. Expect to pay more through these outlets. Also expect to become an expert in UPS shipping rules. Boatanchors are heavy, and often the cost of shipping one can exceed the cost of the entire unit.


by John Brewer WB5OAU

Don't look as boatanchors as an investment. Get a really grimy specimen and clean and fix it, and coax it back to life. Turn it on with the rest of the room lights turned off. As it warms up look into the insides and see the orange glow from the filaments and the purple fire from the 866's. Watch the giant S-meter come to life, and the dials emit that soft light, framed by your carefully cleaned and waxed cabinet. Rotate the knobs that are of sufficient size and layout to permit easy, flywheel smooth adjustment.

Maybe tune to the BBC on your NC-183.... watch the S-meter climb as the full audio comes out from the 6 watt output stage as you crank back the RF gain. Fiddle with a few more knobs (boatanchor operation does not need to be a passive experience) to get it set just the way you want it.

Then you'll know why boatanchors are such pleasent things to own. Like mine, your transceiver may become a very expensive frequency counter and RF generator used to align the 'Real Radios'.

Credits -

The original boatanchors e-mail list was created by Jim Lockwood KM6NK, and is currently managed by Jack Hill W4KH -- its high signal-to-noise ratio is a fine example of good use of the Internet.

Rick Stealey K2XT got the newsgroup created as an official newsgroup.

The first version of this FAQ was put together by John Brewer WB5OAU/4 for the original boatanchors e-mail list.
Other info has been gathered from various sources by Michael Crestohl W1RC and Nick England K4NYW.

Nick England K4NYW created and maintains this FAQ site.

A big Thank You to all who have contributed !

Please send contributions and corrections to

Disclaimer - While we believe this info is reasonably correct, all responsibility for use of this info is yours, not ours.

BE CAREFUL - Boatanchors are heavy and contain lethal voltages !!