Dave's Homemade Radios - Frequently Asked Questions

General and Personal Questions

Q: Why are you doing this?

A: By this, I assume you mean this site? This is my get rich quick scheme. It is also my ego builder. But mostly because I have always liked sharing information with others. This is known as mrknowitallism in the shrink trade. The more you buy from me, the richer I become. The more you say nice things about my radios, the bigger the ego gets. Since 1996 I have used the internet for my own pleasures. Many people have put up sites that have helped me a lot. This is my chance to give back a little.

Q: Your pages look great. What software do you use to make them?

A: Thank you, cousin Bob! To write the HTML code I use Macromedia's Homesite. I also use CSS Style Sheets and a good program for that is Top Style. Both of these programs require manual coding. I use PhotoImpact from ULEAD. This came with my scanner and it works great for formatting my pictures and making my schematic drawings. The banners and some of the backgrounds are made with Banner Maker Pro.

Q: Where do you get your ideas?

A: Some of them are my original ideas, or ones that I hadn't seen before. Many ideas I find from the internet or some of my many friends that I have met because of my web pages. I am grateful for all the ideas that I have stolen.

Q: Your loops look fantastic. How come they aren't for sale?

A: Thanks again cousin Bob. Some how I feel you are going to hit me up for a few dollars the next time you see me. Anyway, the loops are for sale! Shipping them is a major problem. They are very light but due to the large package they require, UPS gets the 30 pound shipping rate. While I don't blame them, it adds a lot to you getting one of my creations. The main problem is finding a suitable package to put the loop in. I take pride in my packaging. I want everything that I have built to arrive safely. Finding a large enough box is not easy. Pick up sales are welcome.

Q: Where do you get those old time parts?

A: I buy from people selling on eBay and at hamfests, mostly. There are also some speciality stores selling the old time items. Sometimes it takes me months to find the right part. Sometimes it is also very costly.

Q: Where are you located?

A: I am located near Corning, New York, USA. I am about 250 miles (325 km) west of New York City.

Q: How and when did you get interested in radio?

A: I first became interested in radio and electronics at around 5 years old. My father, before becoming an accountant was a radio repairman. I learned from watching my father fix radios. Later he got his ham radio license and that interested me too. I built my first crystal set when I was 8 years old.

Q: Are you an engineer?

A: No, I am not an engineer. I might be best described as a technician. My projects probably show that. Not a lot of theory and math on my pages, mainly a how to make your own style is used here. There are plenty of people out there that know the theory better than I. Therefore I let them tell you how all this works.

Q: Do you offer kits?

A: Sorry, no I don't. Some of my projects are built with parts that aren't made any longer and are in short supply. If you would like a kit, try Peebles Originals. Mike Peebles designs these kits and you are nearly guaranteed of success. If you see a part in one of my projects that you would like, e-mail me and ask if I have any more. Sometimes I have a few of this or that but not enough to put in my web store.

Q: Have you ever gotten knocked on your ass by one of your radios?

A: Not recently. In my old age, I have become much more careful about where I put my hands. In earlier times it happened a lot. I have become a lot more careful now. If this is a worry to you or if you are accident prone, you should only do transistor radios, or tube radios with a 22.5 volt B+.

Some of the projects that I have are authentic old time circuits. Safety wasn't a major issue back then. Some of my projects have the B+ running through the headphones. I have never heard of anyone getting hurt with this arrangement but it could happen. So if you are using a non battery high voltage circuit, you may want to put in a transformer to keep yourself isolated from the voltages.

Q: What do I do if there is an error on my pages?

A: Let me know. I am especially interested in finding out if a link I made to one of my own pages is bad. My site is very active and sometimes complicated. If I add a page, I sometimes have to change a dozen internal links. Sometimes I miss a couple of them. Spelling errors or word usage errors aren't of a big concern to me. This is a radios page, not a grammar page. However if you tell me about it, I won't byte your head off.

Q: When you designed your web site, what was most important?

A: I designed this site to look good but be easy for the user. None of my pages are more than two levels down from my main radios page. My pages were designed for use with a minimum of 800x600 pixels. This is the minimum video setting of the XP operating system and I thought it to be a good place to start.

The pictures are sized so that my dial up surfers don't have to wait forever for my pages to load. I balanced this with having worthwhile quality pictures.

I don't do anything real fancy on my pages, so that all browsers are comfy with the code. I use a small amount of java script, mainly at the bottom to show you when the page was last updated.

I kept the blinking objects down to a minimum. I don't need to distract you. My web host delivers the pages quickly enough, so you only have to wait for your ISP and not the web server. Basically, while this is a slight ego trip for me, the main purpose is to offer what I know to you in the best way possible.

Q: What size colander do you wear, Dave?

A: The large size.

Q: You are obviously intelligent, but wearing a colander on your head?

A: When I want to have spaghetti for dinner, I can always remember where I put my colander. YOU tell me where I should wear it.

Q: Why don't you date your radios?

A: If I dated my radios, my girlfriend would really get mad at me. She supports me now, so I can hardly afford that. BTW, date my radios? What kind of a weirdo are you anyway??

Crystal Radio Questions

Q: What is the furthest station you have heard on your sets?

A: The furthest is CMKA in St Germa, Cuba. That measures 2410 km from my location. They run 150kw. My crystal radio logs may be seen here.

Q: Which coil makes the best coil?

A: You have several to choose from. Cylinder, rook, spider and toroidal to mention a few. Toroidal coils are nice for their small shape and not requiring a lot of wire. Cylinder coils are ok if the windings are spaced. Otherwise they are at the bottom of the performance heap. Rook coils are nice but they may not hold up real well with the glue. My favorite are spider coils. I have a spider coil web page that might be helpful. I use which coil will fit the package I intend on using. Also the looks are important.

Q: Are there differences in variable capacitor qualities?

A: There sure are. Many of the variable capacitors out there, even the ones that I sell are just run of the mill types. They are fine for building crystal sets for the casual builder. The best capacitors are ones that have ceramic insulators instead of phenolic. Even better are capacitors with silver plated plates and high quality wipers. Of course these are going to cost a lot more. They are highly recommended if you are going to use the large litz wire for coils. That way the capacitor doesn't kill the Q that you paid so much to get with the litz.

Q: Are sound powered headphones really necessary?

A: They really aren't for the casual builder but if you want to hear the weak dx stations, sound powered headphones are required. I used a crystal earphone and a set with smaller litz and regular capacitors and I heard a lot of stations. But I heard more with larger litz, better capacitors and sound powered headphones.

Tube Radio Questions

Q: What does hand capacitance mean?

A: Hand capacitance refers to the unwanted tuning of a radio when you move your hand near the set. I have even noticed this effect in high performance crystal sets. To eliminate this bothersome occurrence, it might be necessary to move the tuning capacitor back further and use an insulated shaft coupler to keep the metal away from your hands. Also, installing a grounded piece of metal behind the front panel helps. Look at my three tube all wave radio as an example.

Q: My radio doesn't regenerate. What's wrong?

A: Problems with regeneration can be caused by having the two coils out of phase. For regeneration to occur, the two coils (main and the tickler) have to be in phase. Try switching the wires to one of the coils.
If the regeneration only occurs at the high end of the band, try increasing the number of turns on the tickler coil. Some of the older tubes have a lot of problems sometimes amplifying. There are other reasons that your set might not regenerate. Check your wiring and circuit accuracy.

Q: What are the best tubes to use?

A: It depends on the radio you want to build. If you want something that looks real old time, you can use a #30 or an 01A type tube. If you want to build a tube set without regard to the tube shape, I would highly recommend a 1T4 or 1S4 type. They are cheap and really work quite well.

Parts Questions

Q: Where are the connections on those single gang air variable capacitors?

A: There are 4 solder terminals on those capacitors. All those terminals are the same connections. You need only to use one of those terminals. The other connection is made to the frame of the capacitor. This can be done with a solder lug attached with a short screw to the bottom of the capacitor.

Q: Why are the Bogen transformer taps labeled in watts, rather than in ohms and why do the transformers have a voltage rating?

A: Yes, this way of describing transformers and their taps is quite unusual. I learned about this over 30 years ago when I started selling items for public address (pa) systems.

I think it is best to think about the fact that the people that install these systems are not anything close to an engineer. Even the people that design a system aren't either. This means that some way had to be found to simplify the design and installation of a pa system.

A speaker system is matched when the load matches the device driving the load (the amplifier). In multi speaker systems, it is desirable to have some speakers louder than others. This is accomplished with the taps on the transformers (looks like 3 db power levels for each step).

If you have a 20 watt amplifier, you should have 20 watts worth of load. This means you could have 4 speakers and transformers with the taps set at 5 watts. Or you could have 8 speakers tapped at 2.5 watts. Or you could have 8 speakers tapped at 5, 5, 2.5, 2.5, 1.25, 1.25, 1.25, 1.25 watts . The power adds up to 20 watts. This is pretty easy. Just think how hard it would be to calculate the impedances?

The systems (amplifiers and transformers) are rated in volts. I believe that this is some number picked to approximate the peak (or may be the rms) voltages on the line. The common voltage ratings are 25, 70 and 140 volts. 25 volt systems don't have any special wiring regulations but the higher voltages do. Some have to be put in metal electrical conduit pipes. Of course the higher the voltages, the higher the impedances. The lines can be thinner or they can be longer or both.

I can tell you that it didn't make sense to me for a long time because I was thinking in engineering terms. I did find a paper written by a pa system manufacturer that explained it all.

Q: What the heck is Garolite?

A: Garolite is classed as a plastic and is an excellent electrical insulator. It's rf properties are unknown however. The do make a nice looking old time front panel for my radios. The material is easy to work with too. I have only ruined garolite by bad measuring and not material failure.