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Mar 05, 2006, 05:11 PM

High band vs. Low band Rx


I've recently come across the subject terminology and am confused by it. I'm
hoping that someone in the group can explain the meaning and significance of
high band vs. low band as it relates to receivers. Does it also relate to
transmitters? If one of my current radio systems operates on channel 40 and
I want to buy a receiver that I can put in another plane to operate with
that transmitter, do I have to buy a high band receiver and then equip it
with a crystal for channel 40?

Harlan


Mar 05, 2006, 05:11 PM
Ed Paasch
Ed Paasch
Guest

Re: High band vs. Low band Rx


High Band versus Low Band is most commonly a distinction made while
discussing Futaba aircraft radio equipment. Futaba dual conversion
receivers are either rated as low band (channels 11 through 35) or high band
(channels 36 through 60). For whatever reason, Futaba doesn't design their
receivers to work with just any channel, they're specifically engineered for
the lower or upper half of 72mhz frequencies.

Basically, if your transmitter is on channel 11 through 35, you need to pair
it with a low band Futaba receiver along with your specific frequency
crystal. If your transmitter is on channel 36 through 60, you need to pair
it with a high band Futaba receiver along with your specific frequency
crystal.

JR, Airtronics, and Hitec all make receivers that can accept any crystal
between channel 11 to 60 on the 72Mhz frequency band.


"[email protected]" <[email protected]> wrote in message
news:[email protected]
> I've recently come across the subject terminology and am confused by it.
> I'm hoping that someone in the group can explain the meaning and
> significance of high band vs. low band as it relates to receivers. Does it
> also relate to transmitters? If one of my current radio systems operates
> on channel 40 and I want to buy a receiver that I can put in another plane
> to operate with that transmitter, do I have to buy a high band receiver
> and then equip it with a crystal for channel 40?
>
> Harlan
>



Mar 05, 2006, 05:11 PM
Martin X. Moleski, SJ
Martin X. Moleski, SJ
Guest

Re: High band vs. Low band Rx


On Sun, 5 Mar 2006 12:16:10 -0600, "[email protected]" <[email protected]> wrote
in <[email protected]>:

>I've recently come across the subject terminology and am confused by it. I'm
>hoping that someone in the group can explain the meaning and significance of
>high band vs. low band as it relates to receivers. Does it also relate to
>transmitters? If one of my current radio systems operates on channel 40 and
>I want to buy a receiver that I can put in another plane to operate with
>that transmitter, do I have to buy a high band receiver and then equip it
>with a crystal for channel 40?


So far as I know, it's an outmoded concept.

Futaba (I think) used to tell people not to change
crystals without having the RX retuned if the change
in frequency was more than plus or minus ten channels.

All of the Hitec RXs I've purchased come without a
crystal. You just buy the crystal you want and put
it in.

It is different, of course, if we're talking about
HAM band receivers and 72 MHz. You can't change
a receiver from HAM to 72 MHz, so far as I know.

Marty
Mar 05, 2006, 05:11 PM
Doug McLaren
Doug McLaren
Guest

Re: High band vs. Low band Rx


In article <[email protected]>,
Ed Paasch <[email protected]> wrote:

| High Band versus Low Band is most commonly a distinction made while
| discussing Futaba aircraft radio equipment. Futaba dual conversion
| receivers are either rated as low band (channels 11 through 35) or high band
| (channels 36 through 60). For whatever reason, Futaba doesn't design their
| receivers to work with just any channel, they're specifically engineered for
| the lower or upper half of 72mhz frequencies.
....
| JR, Airtronics, and Hitec all make receivers that can accept any crystal
| between channel 11 to 60 on the 72Mhz frequency band.

Close, but not quite.

Basically, you take your RX and tune it to a specific channel. It'll
work best at that channel, and as you get further from that channel,
performance will decrease.

JR/Airtronics/Hitec gear is tuned to channel 35 or so by default. So
it'll work best on channel 35, a little less good at 34 or 36, etc.
But even channels 11 and 60 will work reasonably well, even though
we're 25 channels away.

Futaba gear is tuned to channel 23 (low band) or channel 48 (high
band) give or take a channel or two. The advantage of doing it this
way is that as long as you keep in the correct band, you're at *most*
12 channels away from optimum rather than the maximum of 25 channels
that you could be away in the case of JR/Airtronics/Hitec. The
disadvantage is that either 1) you have to keep your RX's restricted
to the proper band crystal, or 2) you can be even more than 25
channels away from optimum. If you put a channel 60 crystal into a
low band RX, you're 37 channels away from optimum. *It will still
work*, but performance (i.e. range) will be reduced, though exactly
how much is hard to say.

With the right skills and tools, a RX can generally be tuned to any
specific channel, whether it's high band, low band or `middle' band.
(As long as you stick to the same band. You cannot simply tune a 72
MHz RX to 27 MHz, for example.) Tuning your RX to your specific
channel will give the best performance, but the gain usually isn't
that signifigant unless it was way off before.

If you buy a brand new RX, it's probably tuned to approximately
channel 23 (Futaba low band), 48 (Futaba high band) or 35
(JR/Airtronics/Hitec), no matter what crystal is actually in it.

However, if you then send it in to the factory for repair or retuning,
they'll probably tune it directly to the channel of the crystal in it,
which will give you the best performance.

Though really it rarely matters. You may get 2 miles range with a
perfectly tuned RX, or 1 mile range if it's a low band RX on channel
60. You probably can't see your plane at over 1/2 mile, so ...

(To be fair, my figures are guesses. Do your own testing.)

--
Doug McLaren, [email protected]
Meet the Girls with the Thermo-Nuclear Navels!
-- Dr. Goldfoot and the Girl Bombs (1966)
Mar 05, 2006, 05:11 PM

Re: High band vs. Low band Rx


Thanks, guys! I appreciate the comments. Most of my equipment is Futaba, so
I guess I'd better be "Heads up" about the subject.

Thanks,
Harlan


Mar 05, 2006, 09:11 PM
hed
hed
Guest

Re: High band vs. Low band Rx - Test


Please pardon the one-time test


Mar 05, 2006, 11:11 PM
Martin X. Moleski, SJ
Martin X. Moleski, SJ
Guest

Re: High band vs. Low band Rx - Test


On Sun, 5 Mar 2006 19:46:54 -0600, "hed" <[email protected]> wrote in
<[email protected] >:

>Please pardon the one-time test


Ego te absolve ...

Marty
Mar 06, 2006, 01:11 PM
Ed Paasch
Ed Paasch
Guest

Re: High band vs. Low band Rx


Thanks, Doug! I knew somebody out there would be happy to expand upon my
reply.


"Doug McLaren" <[email protected]> wrote in message
news:vWGOf.20358$n%[email protected]
> In article <[email protected]>,
> Ed Paasch <[email protected]> wrote:
>
> | High Band versus Low Band is most commonly a distinction made while
> | discussing Futaba aircraft radio equipment. Futaba dual conversion
> | receivers are either rated as low band (channels 11 through 35) or high
> band
> | (channels 36 through 60). For whatever reason, Futaba doesn't design
> their
> | receivers to work with just any channel, they're specifically engineered
> for
> | the lower or upper half of 72mhz frequencies.
> ...
> | JR, Airtronics, and Hitec all make receivers that can accept any crystal
> | between channel 11 to 60 on the 72Mhz frequency band.
>
> Close, but not quite.
>
> Basically, you take your RX and tune it to a specific channel. It'll
> work best at that channel, and as you get further from that channel,
> performance will decrease.
>
> JR/Airtronics/Hitec gear is tuned to channel 35 or so by default. So
> it'll work best on channel 35, a little less good at 34 or 36, etc.
> But even channels 11 and 60 will work reasonably well, even though
> we're 25 channels away.
>
> Futaba gear is tuned to channel 23 (low band) or channel 48 (high
> band) give or take a channel or two. The advantage of doing it this
> way is that as long as you keep in the correct band, you're at *most*
> 12 channels away from optimum rather than the maximum of 25 channels
> that you could be away in the case of JR/Airtronics/Hitec. The
> disadvantage is that either 1) you have to keep your RX's restricted
> to the proper band crystal, or 2) you can be even more than 25
> channels away from optimum. If you put a channel 60 crystal into a
> low band RX, you're 37 channels away from optimum. *It will still
> work*, but performance (i.e. range) will be reduced, though exactly
> how much is hard to say.
>
> With the right skills and tools, a RX can generally be tuned to any
> specific channel, whether it's high band, low band or `middle' band.
> (As long as you stick to the same band. You cannot simply tune a 72
> MHz RX to 27 MHz, for example.) Tuning your RX to your specific
> channel will give the best performance, but the gain usually isn't
> that signifigant unless it was way off before.
>
> If you buy a brand new RX, it's probably tuned to approximately
> channel 23 (Futaba low band), 48 (Futaba high band) or 35
> (JR/Airtronics/Hitec), no matter what crystal is actually in it.
>
> However, if you then send it in to the factory for repair or retuning,
> they'll probably tune it directly to the channel of the crystal in it,
> which will give you the best performance.
>
> Though really it rarely matters. You may get 2 miles range with a
> perfectly tuned RX, or 1 mile range if it's a low band RX on channel
> 60. You probably can't see your plane at over 1/2 mile, so ...
>
> (To be fair, my figures are guesses. Do your own testing.)
>
> --
> Doug McLaren, [email protected]
> Meet the Girls with the Thermo-Nuclear Navels!
> -- Dr. Goldfoot and the Girl Bombs (1966)





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