PW 160M AM Mobile - 1960's style

[W1GFH]

Ran across this scan of a 1963 Popular Electronics article describing a 10-watt, 4 tube 160M mobile AM transmitter:

http://smg.photobucket.com/albums/v652/ranickel/Top%20Band%20Goes%20Mobile/

The difference between this and most other fanciful magazine projects is that this particular rig was apparently very popular in the pre-FM repeater days. According to W9LBB on the Glowbugs list:

Back in the 1960s when dinosaurs ruled the earth and I was WA9QMB in Chicago, the 160 mobile crowd around Chicago swore by these little rigs. We used to hang on 1810 KHz with 'em. One 6AQ5 is the final amp. One is a modulator. The third is a crystal oscillator. There should be a 12AX7 or 12AT7 in there someplace too as a mike amp and audio driver. The design was good for 10 or 12 watts out of AM. PA plate tank was a Pi network, and usually the oscillator tank was a slug tuned coil that was parallel tuned with a small variable cap sometimes; if not, there was a fixed cap across it. They're usually wired for 12 VDC on the filaments (guys with older cars wired for 6 VDC). Plate voltage was usually derived from surplus dynamotors, and was in the 250 - 350 VDC range, depending on what Joe down at Arrow Electronics on Surplus Row had on the shelf that week. These rigs, into a decent mobile antenna, usually gave you solid communications for 15 or 20 miles to other mobiles.

Fascinating.

[W5EFR]

I think this is a cool little project.

Might be a good AM Home-brew beginners circuit.

[K1MVP]

I think this is a cool little project.

Might be a good AM Home-brew beginners circuit.

Could be a nice PW project,--except that 160(in my experience) has never been a good band
for qrp and "compromise" type antenna`s IMO.
                                                73, K1MVP

[Carl WA1KPD]

except that 160(in my experience) has never been a good band
for qrp and "compromise" type antenna`s IMO.
                                                73, K1MVP

I run a 6V6 plate modulated by a 6F6. I have a screen resistor I toggle in on the final that will drop the output to 1/3 pf a watt. I have had good qsos without revealing the power level. Granted I would not run it on a summer evening during a contest, but the band will surprise you.

I have also worked 40 miles away daytime with a mobile set up on 160

[K1MVP]

except that 160(in my experience) has never been a good band
for qrp and "compromise" type antenna`s IMO.
                                                73, K1MVP

I run a 6V6 plate modulated by a 6F6. I have a screen resistor I toggle in on the final that will drop the output to 1/3 pf a watt. I have had good qsos without revealing the power level. Granted I would not run it on a summer evening during a contest, but the band will surprise you.

I have also worked 40 miles away daytime with a mobile set up on 160

Great,if you can do it,--but I am used to running qrp on 40 and 20,--and even 80 meters.--I tried
160 last year using my FT-101e with a homebrew trap antenna for 75 and 160, and while I got
out ok on 75,--160 was a "pain" as far as signal strength(guys had trouble hearing 30 watts on 160).

Another problem,--I had was I just could not get the height and the antenna was very "narrowbanded".
I made up my mind after that that I would need some "serious power",-- 200 watts plus AND the the
antenna would have to be much higher than only 30 feet.

                                                    73, K1MVP
                                               

[Steve - WB3HUZ]

Ya gotta remember, those guys using these PW mobile rigs back in the day were covering ranges around town, 10-20 miles or so. This was all groundwave propagation where the vertical antennas worked best. Signal strength probably wasn't a big problem.

Plus hams were smarter back then, so they could copy weaker signals.

[W5EFR]

I run a 6V6 plate modulated by a 6F6. I have a screen resistor I toggle in on the final that will drop the output to 1/3 pf a watt. I have had good qsos without revealing the power level. Granted I would not run it on a summer evening during a contest, but the band will surprise you.

I have also worked 40 miles away daytime with a mobile set up on 160

Sounds like a cool rig...

Any Photos?

[Todd, KA1KAQ]

Plus hams were smarter back then, so they could copy weaker signals.

Which is probably a lot closer to the truth than we'd care to admit in today's 'New Age' amateur radio world.

[Carl WA1KPD]

Here you go.
The goal was to build it using stuff from the junk box that might not otherwise be used.

[Carl WA1KPD]

Plus hams were smarter back then, so they could copy weaker signals.

Which is probably a lot closer to the truth than we'd care to admit in today's 'New Age' amateur radio world.

What a bunch o' buzzards. Same thing they said about us in the 60s Todd.

I can hear it now

"CQ CQ CQ from KA1KAQ No lids, no kids, no post 06 tickets need respond."

[Todd, KA1KAQ]

Here you go.
The goal was to build it using stuff from the junk box that might not otherwise be used.

This rig shows a clear common sense approach to hombrewing. The green pilot light proves that the person who built this knew what he was doing. Green = go, Red = stop.

"CQ CQ CQ from KA1KAQ No lids, no kids, no post 06 tickets need respond."

But we want to get more kids involved, so we'd have to change that part in favor of something even more catchy, like... "No out-of-area vanity calls...". Would be especially fun on CW!

[flintstone mop]

I'll echo the comments about 160M. I have had surprises from ops in their shack using 20 Watts, but low power and a mobeel antenna might be stretching it a bit. There was an operator who had a very respectable mobile signal with a 500 watt linear and a very long antenna on his tractor trailer. The name and call aren't in my short memory banks at this time.

Fred

[K1MVP]

Plus hams were smarter back then, so they could copy weaker signals.

Which is probably a lot closer to the truth than we'd care to admit in today's 'New Age' amateur radio world.

Todd,
Hams might have not been "smarter",--but they were more willing IMO, to work at pulling a weaker
signal out "of the mud".
Seems like nowadays if a guy is not 40 to 60 db over S9 then some guys just do not want to bother
with the "medium" or QRP ham.

Have built many medium and qrp rigs, both tube es solid state(you have seen some of them Todd),
and have had a lot of fun running half watt rigs,--one watt rigs,5 watts, etc on 40 es 80 cw.

As far as 160,--my latest project on the table IS NOT a qrp rig,--its a homebrew 813 linear
to give me a bit of "horsepower" on that band.

                                                          73, Rene, MVP

P.S,--got to get back to finishing my homebrew 40 meter qrp tranceiver(cw,--no less)
 

[WU2D]

This is my 160M widowmaker. It is powered by an AC full wave doubler right off the line and the tubes are series string heaters. It puts out about 2 Watts. It was hard to make contacts but I made a few. Pete WA1VZR used to hear me in Maine (when he lived up there).

This thing was written up in ER a long time ago. It had a 12AU6 PTO, a 50C5 Final and 12AX7 Speech and a 50C5 true Heising modulator. The silver thing is an old choke from an ARC-5 screen modulator.


Mike WU2D

[K1MVP]

WU2D,
Nice,--that looks like a neat little rig to feed a small homebrew amplifier,--tube or solid state.

                                        73, K1MVP

[W1GFH]

UD, nice construction. What's the chromium rig seen in ur avatar? Give us a closer look.

[W5EFR]

Cool Rigs!

Hey Mike, I have that article on the Widow Maker...

I haven't got brave enough to build it! LOL

Have any problems with 60Hz hum in the audio?

[WU2D]

Hi Guys,

Simple rigs are fun to build, but when you are done, they still are kind of PW for all of that work. The rig in my avatar is a classic 6AG7-6L6 CW rig which has a type 80 rectifier and a VR-150 regulator. It is rock solid and has a nice tone - about 8 Watts out.
I also included the schematic from the September 1997 ER for the Widowmaker 50C5. The power supply was a full wave doubler originally, but I eventually converted it to a half wave doubler so I could have a ground reference on B-.

Actually there was no real hum problem.

Mike WU2D

[W5EFR]

So what do you think is a good minimum wattage output to build for on.. 75M?

I don't have the real estate for 160M antennas..

[WU2D]

Frank GFZ says that anything less than 4 KW into a lazy H at 200 feet is questionable...

Actually, I used to use a GRC-9 on 75M with 8 Watts out but it only worked when the band was favorable for short hop propagation around New England. Weekend mornings and afternoons are good times for low power. 7PM to 10PM is not!

My guess is that 2 to 10 Watts of AM would be fine for local 100 - 300 mile stuff. As usual, only good antennas need apply.

Mike WU2D