Pre 1950s aerial impedance and feeder setting up

[Malcolm T]

Before the advent of the handheld antenna analyzer MFJ VNA etc just how did the military and commercial aerial erectors of the pre 1950s set up HF aerial systems and achieve the correct feed line impedance's and feed points with open transmission lines suspended from poles or wooden towers.
I can only think of a smith chart being part of their tool kit, what else did they have ?.

[Terry_VK5TM]

They had transmitters that weren't particularly fussy about the impedance of the transmission line/aerial because they had tuning/loading circuits in them.

Also they were valve gear and not so quickly damaged as the soon to arrive transistor stuff.

A look through the ARRL QST magazine of the 50's will show what was around at that time https://worldradiohistory.com/QST.htm

[Radio Wrangler]

You might miss articles in any single copy of QST, so you may be better looking in a 1950's ARRL handbook where you'll find the theory and the better constructional stuff collected together.

David

[Malcolm T]

Yes thanks for the replies

[Cruisin Marine]

They would probably have used an RF Thermcouple Ammeter and base insights on the readings around that and work out the efficiency of the antenna etc.

They would also have an impedance bridge if they were lucky.

Old ARRL yearbooks are the place to investigate, they are a superb read anyway.

[G3PIJpeter]

Some idea of the SWR on a balanced feeder could be gained from a 'Twin Lamp' indicator - see QST October 1947 pp. 22-23 at
https://worldradiohistory.com/Archiv...ST-1947-10.pdf
I suppose that physically larger versions could be made for wider-spaced lines such as the then-ubiquitous 600-ohm ladder line.
- Peter

[Malcolm T]

Thanks for the link Peter , yes i have seen reference to this some time ago but cannot remember where.
I also seem to remember reference to the riggers using binoculars to read RF meters at the top of the aerials as power was applied, or if the aerials were set up much lower to ground and then hoisted up ?.

[G3PIJpeter]

Originally Posted by Malcolm T

I also seem to remember reference to the riggers using binoculars to read RF meters at the top of the aerials as power was applied ...

When I first started transmitting with G3PIJ, I was completely ignorent of SWR. It was not in the RAE syllabus. Coax from the Top Band transmitter fed a parallel tuned circuit with a tapped coil and variable capacitor, to which a 50-foot wire and a water pipe were attached. ATU coil taps and VC were twiddled, together with the tune and load controls on the transmitter, until the field strength meter on the window sill showed maximum burn. I think that's how most of us did it in 1961.
- Peter

[MIKEG4IIA]

Yep! Tune for "maximum smoke"

[G6Tanuki]

A neon bulb from the antenna-terminal to ground as a voltage-indicator, and a flashlight-bulb [or car sidelight bulb] in series with the end-fed antenna as a current indicator... twiddle your Pi-tank capacitors to get the brightest glow!

There were also thermocouple RF ammeters - I have a US-made "Westinghouse" one. Seems it was spoecified for the US Navy with their designation CAT-22035

Calibrated to 15 Amps!