I just bought a Hallicrafters S85 on eBay with a tuning eye installed. Other than taking up the space that could be utilized for an S meter, are there any other downsides to this alteration ?

Why not leave the "EYE" and add your New/old "S" meter ?
I can't deceide whether to add a "EYE" or "S" meter to one
of my S-38's NO room for both..
Does anyone know where to install the "EYES" wiring I guess that would
depend on the tube number ??
I Love reading these Forums better than T.V. Thanks All....Freddbro...

I cant envision any purpose for an eye tube in any "communications" radio and especially ones with barn door broad tuning.
The few higher end models that used them in the mid 30's quickly went to an S meter after about a year....the useless fad was quickly over.

Carl

Dear Carl, I bought a SX-41 someone had added an "EYE" to it and it looks
real Si-Fi Retro... Maybe I should add an "S" meter instead and be conventional?
I'm going to try to attach a meter I bought, not sure what it is? But it "Fits"
into the 50's 60's Nuclear Bomb Age... Same Era as the Hali. S-38
Can anyone identify the meter?? "S" "TUNING" "VU" ???
Please Advise and Thank You All..... freddbro..

I kind of enjoy that green eye winking at me from my halli sx-11.

I have several radios with tuning eyes. I love them.
As far as communications receivers go, I'll have to go with Carl.
We might very well have the meters calibrated to the 50 uv for S9 signals and that in itself
can come in quite handy for providing accurate signal reports.
Tuning eyes, on the other hand, provide a "maximum" signal strength and can come in quite handy for tuning a broadcast signal and they are pretty 30's and 40's retro.
One thing not covered is using them as a modulation indicator.

I have plans to put one together for my AM transmitter. Calibration is a snap and the winking eye can identify hum as well as max modulation. Heck, you could even have a bank of them to show different audio frequencies while modulating.
The circuit is so simple and easy to build it could be considered an afternoon job.

Now.....where can I find escutcheons for the eye that aren't made of plastic.
Pete

Dear Pete, I have gotten some sice "Escutucheons" on vintage test equipment also tubes
with wires included. Would you post the "Afternoon Project" for "Eye" tube modulation
project you mentioned ?? Thanks, Freddbro

CAN ANYONE IDENTIFY THE ATTACHED METER PHOTO ??? freddbro

The attached pic looks like something one might find on a Geiger counter or radiation meter/indicator.

A tuning eye looks very nice on some of the early receivers. I think the National NC-100X is one of the best looking early receivers and it wouldn't look as nice with a meter (and believe me I know because one of my two NC-100X receivers has an S meter that was installed in place of the eye). The RCA ACR-111 and ACR-175 with their panels balanced by a real eye on one side and a fake on the other are also nice appearing receivers. When I bought my ACR-111 the fake eye had been replaced by a meter but it will get a repaired front panel and new fake eye during restoration.

The NC-100X manual includes instructions and a chart to measure signal strength based upon RF gain setting and tuning eye closure. Not exactly convenient but it is an interesting section. Of course National was a great believer in charts with the NC-100X (and the HRO series prior to the 50) since you had to use a chart to figure out the frequency.

S meter calibration is about as trustworthy as your typical 60's era used car salesman Different manufacturers used different standards for input level for "S-9" and once set the level required for S-9 will vary across bands and even within band based upon changes in front end tracking and oscillator injection level. Multiple conversion receivers with broadband tuned first IF sections will generally have significant gain variation across the IF bandpass unless they are very carefully aligned.

The db over 9 calibration tracks the output from the signal generator pretty closely for my SX-88 but many of my other receivers have S meter readings that are either highly compressed or highly expanded once the S-9 level is exceeded. They are handy for peaking the preselector and providing relative reports of signal strength.

Rodger WQ9E

Gotta disagree Rodger. I use an early NC-101X with the eye often and its really only useful on CW where you dont give out anything over a 599 anyway so its easy to fudge. But on AM the other guy wants a report or you get into a roundtable or the Antenna 1 vs Antenna 2 issue.

OTOH since the HQ-129X only goes to S-9 I sometimes PO a few with a stingy report.

And with the 1935 HRO the best I can go is R-5 which throws many off balance.

Its all a game and relative anyway, an accurate S meter on vintage gear is about as scarce as an honest mpg report.

Carl

My 101X is the later S meter version, I have it paired with a Lysco 600. I rarely use the 100X with a transmitter but I get your point about the convenience of an S meter.

I had forgotten about the "only goes to S-9" on my HQ-129X, I often talk to one station on 75 who always want to know how many db over S-9 the meter indicates. I am going to have to use the 129X soon just to throw him off. My Stancor 20P is on the way so maybe Tuesday or Wednesday I will pair it with the HQ-129X and give out some disappointing signal reports.

You could put a scale around the 101X eye tube and give one of the new appliance operator a signal report in degrees of closure-that should create an interesting discussion. Then ask him to wait a moment while you pull out your slide rule to convert degrees to R units.

Rodger WQ9E