Newbie Vintage Guy Needing Help!

[AB5OR]

Let me preface this by saying, I am a young fellow (33, not too young), and at a recent hamfest, the vintage bug bit, though I didn't buy anything.  I have since acquired a Viking Challenger, a Viking 1 converted to a 2, and I am in the process of getting a receiver. I want to restore a Valiant at some point, might just collect them all!  Anyhow, my father ran a two way radio shop for years, and has good solid RF knowledge base as well as tube knowledge.  I am going to rely on him and his test equipment quite a bit to help me.   I understand the basics, and my primary interest (other than AM ragchewing and CW) is to LEARN how these things really work.   I admire how they were made, and I love the heat and glow of tubes (real radio).

Having said all that, I can't figure out something.    On modern transceivers, I have a built in tuner to feed my 160 meter inverted L that works on every band but 30.   I can always switch antennas, but I am wondering how to correctly tune to these boatanchors.

Normally, radios today have a 50 ohm RF port, and you simply hit the tune button.   Obviously that's not the case with boatanchors. 
So, my question is, what do I need?   Some kind of external tuner I suppose, vintage or modern.   What would you do?   I understand the need for TR switches or relays, but the tuner is where I get confused.

And, in so doing, how does the tuner affect how you properly tune the radio?

I know this is a newbie question, but that's what I am....

73, and thanks in advance.   - Joe AB5OR

[W1AEX]

Hi Joe,

It will be necessary to add a piece of equipment that is absent from many modern-equipped stations. That would be a nice 50 ohm dummy load that can be switched in so that you can accomplish the tune-up sequence for your vintage gear. Once it's tuned up at the frequency you wish to use, assuming you have a resonant antenna, switch over to your antenna and if the frequency is clear, transmit and touch up the tank circuit plate and loading caps so that your plate current is correct, and you should be good to go.

If you are going to use your inverted L and a tuner, drop the transmitter grid drive to produce a 10 - 15 watt carrier, and adjust for best match, then bring the grid drive back up to spec, touch up the plate and loading caps in the rig's final, and you should be good to go.

Nice choice of gear you have started to pile up there!

73,

Rob W1AEX

[AB5OR]

Well, thanks for the information.   That makes sense.    Another really newbie question...  I know you zero beat the transmitter with the receiver.  If you are using a TR switch, I am guessing there is still enough drive there to hear the carrier on the RX side, correct? 

[k4kyv]

You don't HAVE to have a 50-ohm link anywhere between the transmitter and antenna, unless you are using one of those modern rigs designed to operate into this load impedance with little leeway.  The pi-network in most "vintage" ham rigs will work into a wide range of load impedances, as low as 30 ohms and as high as several hundred ohms.

The outboard tuning unit you will need depends entirely on the antenna you will be using.  If it is a coax-fed dipole, the rig will likely work just fine without any kind of tuner.  If you are running open wire balanced line, I would  recommend a balanced tuner, something like a Johnson Matchbox, or a home-brew link-coupled tuner.  Circuits can be found in many editions of the Handbook.

If the SWR of the coax fed dipole becomes excessive at certain frequencies and the rig will not load properly, an unbalanced "transmatch" will work. It will cancel out the reactance and present a usable load impedance to the transmitter, allowing the rig to load up normally, but of course, will not affect the actual SWR on the coax.  But if the SWR is less than about 3:1, don't worry about.  Hams these days have unnecessarily become obsessed with SWR.

If you are running balanced tuned feeders, avoid one of  the bogus tuners that prevail on the market these days, which run an unbalanced T- or L- network into a balun, which feeds the balanced line.  Baluns are OK when they work into a proper non-reactive load, but extremely poor performers when working into a random load resistance with significant reactance. The balun coil may run hot, and if it uses a ferrite core, the core may even be driven into saturation enough to become non-linear at the operating frequency, resulting in a wide signal and radiated harmonics.

[Todd, KA1KAQ]

Don is dead on with the tuning info, Joe. A tuner is most helpful when using one aerial for multiple bands, or for something like a dipole cut for one end of the band vs the middle. I've run coax-fed half wave dipole for decades and had virtually no problem tuning them straight off the back of the rig.

The older rigs are certainly more 'hands on' which, for me, is a big part of the fun. Peaking and dipping are terms you'll come to understand and be able to perform in your sleep. And best of all - you can actually repair the older gear without having to send it back to the manufacturer. Vacuum tubes and transformers are much easier to service than the current SMT stuff.

My advice would be to throw up something simple like a 40m dipole for experimenting when you first put the old gear on the air. This will allow you to get familiar with the general tuning and operations of the rig before adding a tuner or balanced feeders to the mix. Of course, if you're already familiar with the latter, then simply add the dummy load step mentioned by Rob to tune the rig, then adjust or touch up the tuner afterward. Be careful about going back to re-tune the transmitter once it's set up or you'll end up going back and forth chasing your tail.

[KA3ZLR]

HI,

Before you plug anything in make sure you have a good ground to all cases
Definite First thing to do.

73
Jack
KA3ZLR

[KA2DZT]

Only one newbie question per thread is allowed

Try to start out with one or two bands  75M and 40M are the best to start with.  A simple dipole cut to the correct freq. and fed with coax is the easiest to get up.  You will not need a tuner with the resonant antennas.  Also, you don't need any baluns, just connect your dipole directly to the coax and then connect it to the rig.

A dummy load is good to have but if you don't,  just tune up on the air when the freq is clear.  Or, if Don is on, you can tune up on his freq.  Don won't mind.  You won't be able to strap him anyway.

As always, solid advice,

Fred

[KA3ZLR]

Light-bulbs make a quick Dummy load in a Pinch.


73
Jack
KA3ZLR

[iw5ci]

I use this approach to join a QSO:

I tune the receiver on a guy that is trasmitting (this does not assure that you are tuned with all the other guys as many of them have old gear with some drift but is a good starting point ).
Then i switch to the dummy load and i sync the tx over the RX frequency with the spot mode. Then i tuneup the tx on the dummy load and at last i return to the risonant antenna and start my qso.

If you are a newbie , sometimes the qso has already ended before you have finished the process 

if i want to make a call on the net frequency, after tuneup, i use a nixie vintage digital counter to set my tx frequency and then i tune the receiver on that frequency with the "spot" of the TX.

If you don't want to buy a digital counter, you need a receiver with a resolution of 1 KHZ and the provision of a calibrator.

A good choice is a Collins 390 or , if you like a receiver matching the style of your TX, for example a National NC-303 with the crystal calibrator.

[WQ9E]

As others have stated, many vintage rigs have very wide range matching capability-sort of like having a built in tuner except it isn't autotune like the modern SS boxes

My novice rig in 1975 was a Viking Valiant and I used it on 80, 40, and 15 with a coax fed 40 meter inverted V attached to the eaves of a two story house.  On 15 meters the Valiant easily matched the antenna and my first CQ was answered by VQ9MI.  80 meters was a bit tougher and it was hard to get the Valiant to load while still staying within the 75 watt novice power limit of the day.  I should have fed the Vee as a top loaded T on 80 but I didn't know that as a novice and it radiated well enough to check into the Mississippi Slow Net during the late afternoons on 80 meter CW.

My Hy Gain Hy Tower is fed as an inverted L for 160 meter use.  I cut the horizontal section a little long so that it has inductive reactance and feed it through a capacitor (made of RG-11 coax) to cancel the inductive reactance.  This allows directly feeding it with 50 ohm coax with a very good match and no tuner is needed.  I have a switch that allows selecting 5 different coax capacitors to provide a proper match across the 160 meter range.  I do use a home built reversible L tuner with my vintage gear in the house radio room to load my 80 meter horizontal loop on all bands.  A nice property of the L network is that it provides a low pass filter action which is useful in taming the harmonic radiation that can be a problem with a lot of vintage gear.  I don't use a tuner in the "contest shack" since the triband  quad and Hy Tower provide a proper match without one.

I don't have my original novice Valiant anymore but a Valiant was the first vintage rig I bought in 1994 (when I was 34) when I started operating AM and using vintage gear.  It remains my sentimental favorite and over the years another Valiant has joined the herd and two Valiant II transmitters await cosmetic restoration.

[KM1H]

I use a Viking I and II CDC and they seem to load into anything. As a kid I ran a Vik I into a 40M dipole fed with 72 Ohm twin lead from 80-10M until I built better antennas.

Agree about the NC-300, hard to beat for looks, stability, and access for replacing paper/electrolytic caps and resistors. The Vik I or II will also require a major recap and likely audio mods once you get it working well as built. Never owned a Challenger, had but didnt care for a Valiant.

Carl

[k4kyv]

A dummy load is good to have but if you don't,  just tune up on the air when the freq is clear.  Or, if Don is on, you can tune up on his freq.  Don won't mind.  You won't be able to strap him anyway.

50Ω, converts to 450Ω by removing the straps.  12 ea. 600Ω glo-bars. Don't know the exact power rating, but each one is 1" diameter, 18" long, hollow in the middle. Will handle the BC1-T full strap for unlimited time.

[K5UJ]

here's the one I made from a parted out WGN DL, four 200 ohmers--with a fan it seems to do okay @ 300 w. and audio.

[KM1H]

Ive got the DL that came with the BC-1T but figure it gets fairly inductive on 80 and up

Also have several monster 600 Ohm Carborundums from military antennas that were built for GW1 but never shipped. Maybe 3" diameter and 24" long.

[k4kyv]

I think the Gates resistors are wirewound.  Mine didn't have the DL in it.  Either removed but more likely never there (I couldn't see any trace of impressions around the holes in the frame from previously removed mounting screws). Those "non-inductive" WWs tend to become reactive at higher frequencies.

My DL uses three banks each of four of the 600Ω resistors in parallel, to give 150Ω per bank. With the straps in place, they are all in parallel to give 50Ω.  With the straps removed, the banks of four are in series, to give 450Ω.  I haven't checked out the reactance at 450Ω, but it wouldn't surprise me to find some reactance on 40m, since the total  length of the series string is 4' 6", not an insignificant fraction of a wavelength at 40m.

[W4AAB]

I am going to have to find some of those resistors. Mine has the Gates DL, but the owner wants it back before I can get the BC1-T moved to the house(hopefully next week).

[WBear2GCR]

One thing to note with the Johnson Viking line, it is a very bad idea to key up with NO LOAD - there is a certain wafer switch under the chassis that is NOT rated to handle the juice when there is no load. It will fry up...

Also, when the rig is not resonated and/or there is no load the plate meter will likely pin... scary the first time that happens. Of course I may not be correct that all Vikers will do that, mine sure does but it was modified... and they are not my mods... (stock meter though).

Anyhow you are on a nice quest... the rigs are very nice, albeit heavy.

Keep ur HANDS OUT of them unless you are sure of what you are doing.
The voltages and currents available COULD KILL YOU in some instances.

                  _-_-WBear2GCR

PS. learn about the "Chernobyl resistor" in the VFO box...

[AB5OR]

Thanks fellas for really great advice.  I am probably going to start a website on our projects.   You guys are a wealth of knowledge.   I'll let you know how it's going. my dad is restoring two Atwater Kents right now too.   Can't wait to see where it goes.   

[KM1H]

Ive a few A-K's here also and have more wood cased consumer radios than ham stuff. Most are AC models from about 1927 and later, Im not that interested in battery sets from before that. I like the window rattling sound of 2 and 4 tube audio amps in the consoles into multiple speakers.

Carl

[Rob K2CU]

Welcome Joe!

You have come to the right place to ask your questions. This group will probably supply you with many alternates to solving each problem you encounter. I strongly urge you to keep us informed of your activities. We all learn something from the questions and answers that fly on this website.

From your initial remarks, You appear to have an inverted L cut to 160 and have been using a modern solid state rig with a built in tuner. Besides an external antenna tuner/matchbox and dummy load, I don't recall if anyone has suggested getting a good VSWR meter. I am guessing that you feed that antenna trough a coax line. IN your setup with the rig with the built in tuner, the VSWR meter will be of little use. The standing waves on the coax line will be there whether you have a tuner of not. The tuner, or transmatch will present a correct load to the transmitter. Many antenna tuner/transmatch units have a built in VSWR meter to assist in the adjustment process. Some will also include a bypass switch so that you can connect to the antenna without the tuner circuit. The tuner I use also includes a 200W dummy load, selectable by the same switch that switches in/out the tuner circuit.

Virtually all hollow state (Vacuum tube) transmitters employ the PI output matching network. It provides the means to match the high impedance (generally over 1K) plate impedance to the 50 ohms or so coax antenna feedline. As previously stated, they can match to somewhere between 30 and several hundred ohms. Not mentioned is that they can deal with a certain amount of reactance in the load as well. When we talk about a 50 OHm load, it is implied that it is a purely resistive load. All loads have some measure of reactance, The antenna is purely resistive only at the resonant frequency. And, it may well not even be 50 ohms at that point. So, when you bring that load down into your shack through some oddball length of 50 OHm coax, you will have some complex impedance, a mix of resistive and reactive components. The beauty of the PI output network is that the loading capacitor on the antenna output side will combine with the reactive component on the coax line as part of the matching process. As long as the antenna reactance is not too large, you may actually tune it out, so to speak. The series inductance and plate tuning capacitor will then be used to match the plate to the load. Note that a VSWR meter in the line at the transmitter will still show the presence of standing waves on the line. The only real problem with this setup is that the RF voltages on the loading capacitor might exceed the breakdown rating with possible arcing occurring. Most loading capacitors are low voltage breadslicers like are used in B'cast receivers. Another potential problem is that with a fixed inductance for the band you are on, the match may be less than desired and the dip in plate current not sufficient resulting more losses, especially in the plate with the possibility of excessive dissipation in the tube's plate. The fixed inductance is due to compromise, mostly to $ave co$t. Some big amplifiers have used a roller inductor at this point.

So, the common practice that evolved is to use an external matching device between the antenna and transmitter. I have four in my shack, only one in actual service. Two do not cover the 160 meter band. With tuners in common place, the evolution of "fixed" output impedance transmitters occurred. And 50 OHms became the defacto standard. In hindsight, 75 Ohms would have been a better choice in my opinion. Even before solid state rigs "fixed" at 50 ohms came about, Some tube transmitters had dropped the adjustable loading cap for switched in fixed values. I use to have an HT-44 that was designed that way. Only had a plate tuning cap to adjust.

So, to sum it up, a tube type transmitter, such as your Viking, on the antenna side of your TR relay, you would have an antenna switch to allow you to select either a dummy load or connection to a VSWR meter to tuner/transmatch to antenna.
The ARRL handbooks have soem good suggestions for station layout/connection schemes.

As to your second question about the spot function, the usual thing is that the spot function powers up the VFO and some driver/multiplier stages. It does not power the final or switch the TR relay, which often is used to mute the receiver. There is usually enough RF leaking from the transmitter to be heard in the receiver and allow zeroing to the received signal. Some transmitters even have a spot level control. In roundtable situations, especially in AM, you zero to someone and then don't play with it unless you get comments about being off frequency.

It would be great if you can get your dad into ham radio too.

Enjoy1

[AB5OR]

Wow Rob,

That was a great post!    I will definitely be updating and asking...   My dad is actually a ham too.   N5VGK.   He just got his extra this year, as he never learned CW, though he is learning now.   We both got back into radio this past year, after being away for a bit of time.   I know the no code licensing has been controversial, but there is no way I can say that hasn't been good for radio.  It's put a lot of guys like my father on the air on HF.   He never learned code before because he literally didn't have time trying to run a business.   But, he's finding he loves HF, and has an interest in CW now.   I've been a CW fellow since the beginning at age 13.    So, having said all that, I really appreciate the response.    Given the pi network, I have another question.   I would really like to operate 80 CW, 3.885 AM, 40 meters, and 20 meters on the vintage gear, at least in theory.   It sounds like I might get by just fine with an 80 meter dipole for all of those bands, especially if I had an external match.   Correct?

[k4kyv]

Virtually all hollow state (Vacuum tube) transmitters employ the PI output matching network. It provides the means to match the high impedance (generally over 1K) plate impedance to the 50 ohms or so coax antenna feedline. As previously stated, they can match to somewhere between 30 and several hundred ohms. Not mentioned is that they can deal with a certain amount of reactance in the load as well. When we talk about a 50 OHm load, it is implied that it is a purely resistive load. All loads have some measure of reactance, The antenna is purely resistive only at the resonant frequency. And, it may well not even be 50 ohms at that point. So, when you bring that load down into your shack through some oddball length of 50 OHm coax, you will have some complex impedance, a mix of resistive and reactive components. The beauty of the PI output network is that the loading capacitor on the antenna output side will combine with the reactive component on the coax line as part of the matching process. As long as the antenna reactance is not too large, you may actually tune it out, so to speak. The series inductance and plate tuning capacitor will then be used to match the plate to the load...

Tubes deliver their output at an impedance of several thousand ohms, so a matching network is necessary to transform the plate impedance of the PA tubes to the load, which is usually low, between a few hundred ohms and <50 ohms. The PI-network or link coupled tank circuit are both excellent configurations to perform this matching function.  OTOH, solid state finals work directly into a low impedance, normally within an order of magnitude of 50 ohms. Therefore, the matching network can be eliminated, replaced by a broadband untuned rf transformer designed to work into a 50Ω non-reactive load. Problem is, most ham antennas do not present a perfect 50Ω load to the transmitter, so an external matching unit is necessary to allow the solid state final to work into an acceptable load, which is usually 50Ω ± a few ohms, close to nonreactive.

Even if the antenna does present a perfect 50Ω non-reactive load to the transmitter, the broadband RF transformer does not offer any rf selectivity, so higher order distortion products and harmonics may be present in the output. To assure a clean signal, the external antenna tuning unit is still necessary.

In other words, with the older tube type equipment, the tank circuit was built in, included in the cost of the rig. To-day, the tank circuit which is still practically as necessary as ever, now comes in the form of an external antenna tuning unit, an outboard unit that cost$ extra.

[MikeKE0ZUinkcmo]

You might keep an eye out on ebay for one of these old mil surplus loads.  I got this one for 45 bucks to the door.   Bird was VERY helpful identifying this unit and sending data for the nearest current product.

[KA3ZLR]

Don,

I didn't quote your piece it's just to big but I agree with what you say man, I like
when the Newbies are being Sold the idea a G5Rv Is a Good antenna. yeah and yer gona
Need That Tuna to get matched up and keep those SWR's down..LOL...they're being
sold for 45 bux a piece what a money maker...

No Grace just Space man..


73
Jack
KA3ZLR