Doug Smith W9WI wrote:
Andrew VK3BFA wrote:
The easiest way is to gt a hard rubbish vcr, (most have been dumped
because of tape transport faults) use the av inputs, and output on a
UHF channel - the modern ones have tunable UHF output.

Not in the States. VCR modulators here output on VHF channels 3 or 4.
(60-66 or 66-72MHz)

If the OP can find a foreign UHF modulator, it should work with US
signals, with two possible issues:

- The sound-video separation is different. This means the sound will be
on the wrong frequency for an American TV. If the OP doesn't care about
sound then this isn't a problem!

- TV channel frequencies are different in different countries. Most
Australian channels don't coincide with American channels. (if a
modulator tunes Australian channels 30-37, the only channel in that
range that corresponds to an American channel is 32, which is American
channel 28)

Are European/Australian VCR modulators continuously tunable? Or can
they only be set to discrete channels?

http://www.73.com/a/0019.shtml offers a "block converter". (among
dozens of other items! It's about 3/4 down the page on the left-hand
side, stock #AE047) It's a broadband frequency converter that will
convert a US channel 3 RF signal up to US channel 37.
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com

Hi Doug,
thats interesting - us in OZ had the same VHF output system years ago,
but when we got UHF broadcasting, all the VCR's went to UHF output.
Most (if not all) are tunable over a narrow range,(via a trimmer cap on
the rear panel) some of the more exotic ones (even from dumpster
diving) have user settable(sp) output with the actual RF frequency on
screen - makes a crude UHF sig gen.

The advantage of the UHF output over the older VHF only is no
co-channel QRM from the strong Ch3 signal to local on air channels.
Agree with the different standards - nowadays, this is not an issue as
even the el cheapo VCR's are multi-standard. Saves having to
manufacture for different markets, and the new chipsets for this are
dirt cheap. Most new ones have an integrated tuner/if/video conversion
"can" - unfortunately, bus controlled so difficult to experiment with
unless you are comfortable with microprocessors. I aint - firmly rooted
in the analog domain!

73 de VK3BFA Andrew