Hi, all! This is my first post on any sort of A/V forum - I never really had a reason to join one before, not having a new or complicated enough setup to be worth mentioning.

And I still don't have one, but I've actually run into a different reason to post. I'm sure you'll get a chuckle out of it, and wonder what the heck someone in 2009 is doing farting around with electronics this old. Anyway, here goes. Please bear with my obvious inexperience - as a kid, I only knew just enough about this stuff to get by, but now I'm in a position where I may have to learn a little more!

I picked up a 25-year-old Panasonic Electrotune at a garage sale this weekend. These are the inputs it has:

http://www.easyscreens.info/gallery/20090616/5.jpg

The coax cable leading out of "VHF 75Ω" was hacked off long ago, leaving me with the screw-terminals as my only inputs. To those, I've attached a matching transformer that ends in a coax connector, which is then cabled to the antenna-out on my VCR (and its built-in RF modulator). The VCR, when powered up, is supposed to display a solid blue screen and the number of the channel to which it's currently set. This was tested on another TV.

The switch under the VCR's antenna-out is set to channel 3. The TV has these channel selector buttons:

http://www.easyscreens.info/gallery/20090616/7.jpg

And this tuning panel:

http://www.easyscreens.info/gallery/20090616/6.jpg

I've selected channel 3, and set it to use low-band VHF in the tuning panel. The problem: no matter how much I twirl the tuning control knob, I can't pick up the VCR's signal. Just static. The tuner itself doesn't seem to be broken - when I disconnect the matching transformer, I'm able to receive over the VHF band (a Christian broadcast, and some sort of service station that loops instructions on how to get set up for digital).

I'd hugely appreciate any ideas you have on what I might be missing. Should I care, for instance, about that "FOR 300Ω INSERT VHF PLUG" bit next to the inputs?

The balun (transformer) should be fine.

Double check:
Antenna properly connected (and working). Test directly to TV first.
Set TV to channel 3 (if you have a channel 3 in your area, use channel 4).

Now, what OTA channels are available in your area? As described for "tuning" channels for the "pre-set" buttons, 2-6 are VHF-low, 7-13 are VHF-High.

Note: when turning the tuning knob, go very slowly. The channel will "tune" and "de-tune" quickly if impatient.

As for the "insert VHF plug". It looks like those black thingy's near the 300 Ohm screw terminals may pull out. Perhaps that needs to be plugged into the "Plug"?

Looks like your VHF screw terminals are ok since channels come in. I'd make sure the 75-300 ohm adapter is passing signal, maybe test it on another tv (or reverse-connect to test if other tv doesn't have screws.) Once verified working, then:

- make sure AFT is OFF, tune VERY slowly as Ratman suggested & also try surrounding tuning knobs, some may not respond correctly due to age.
- try both 3 & 4 on VCR's output.

I can't help but wonder whether he needs to "insert VHF Plug" which shorts the outer and inner of the female 75 ohm jack?

On an old old tv i had, that plug was used to bypass the 75 ohm post & enable the screw terminals for VHF, but this tv may be different so yes, I'd try that too. If you can't find plug just short it w/ piece of wire or foil, shouldn't hurt anything.

On an old old tv i had, that plug was used to bypass the 75 ohm post & enable the screw terminals for VHF, but this tv may be different so yes, I'd try that too. If you can't find plug just short it w/ piece of wire or foil, shouldn't hurt anything.

Do you know what kind of connector that would be called? I imagine it was really commonplace at some point so I'd think that, even today, it wouldn't be too hard to find a proper terminator for it.

Thank you all for your suggestions - I will be trying all of them tonight.

Sorry, I don't remember, it's been a while, but I'd try steps above first w/o it. I don't think you need it though since the VHF screw terminals are working (channels ok w/ antenna). Weak link in signal path is the 75-300 adapter, sometimes connection's broken from coax body to 2 wire. I'd test that to make sure signal's getting through. If still fail after that then just short plug out w/ foil to test. Good luck...

Update:

Well, even after shorting with a "VHF Plug" (I bought a female F-connector, it fit the hole well enough), I still wasn't able to get anything over the antenna inputs except antenna signals. Nothing over the 75-100 transformer.

So, I just stripped the end of the hacked-off 75Ω cable and attached a new female F-connector, and successfully received over that. Maybe the transformer was defective, but it's moot now!

(The center of the screen seems to have some sort of discoloration - nothing too bad, though.)

Maybe that discoloration will disappear with use, after the degauss operates a few times. Make sure no magnets, speakers near the TV.

I have a 1988 Panasonic 25" TV with the same type of antenna inputs. The 75 ohm stub that was hacked off is the signal line that goes to the VHF tuner! To receive VHF via cable, you hooked the cable to the 75 ohm stub. To use a 300 ohm antenna, you plugged the stub into the socket, because the 300 ohm VHF screw terminals go to a 300/75 ohm balun behind the input panel, and the output of the balun is that 75 ohm socket. Without the 75 ohm stub intact, you have no input to the VHF portion of the tuner.

That 75 ohm stub was rather flimsy on these models, but it is vital to receiving either VHF or cable reception on this TV's!