milto

My Feedback: (1)

Need some help on terms:

What is negative shift and positive shift?

What is considered the low/ high channels?

Will a single conversion RX work on a Futaba Conquest TX?

Where do you purchase GWS products?

Thanks for taking the time to answer my questions.

Milt

Rodney

Check out torreypinesgulls.org/Radio.htm and most of your questions will be answered.

Woodsy

First one i can help with, "- & + shift" is wether the pulses between the TX an RX goes high or low from the frequency base line. a neg shift transmitter will NOT talk to a pos shift reciever and vice verse, some TX's are shift selectable like the hitec eclipse 7 and some multiplex units, you can also get shift selectable RX's.

other than that and the Futaba Q the rest of your Q's are country specific

im_a_rcav8r

in short...

*72MHz- Low band channels 11 to 35; High band channels 36 to 60. Receiver crystal channels (11-35 or 36-60) Within Each Band Can Be Changed, and Do Not Require a retuning of the receiver. However you can not change the transmitter crystal to a new channel with out having it tuned. Even if only steping one channel. (ie from channel 51 to 52) In fact this is also dictated by the FCC. I'm sure it is in the AMA rules too.

I have never tried a single conversion RX on a Futaba Conquest TX. You should stick with a dual conversion if at all possible. It is more reliable and in my opinion a better way to go

you can get GWS producs at this link. or goto WWW.*********.ORG

Hope this helps...

Rodney

Sorry Woodsy, your answer is wrong. Hi and low shift is determined by whether the first IF stage frequency is determined by mixing a frequency 11.5 MHZ higher than the transmitted frequency or 11.5 MHZ lower than the transmitted frequency on dual conversion receivers; i.e. by the frequency of the first mixer frequency.

JohnBuckner

My Feedback: (1)

OK Milto how about we make this simple:

1. Negative shift/Positive shift is just slightly different internal modulation senario that was started by Futaba years ago in an attempt force you to buy their products. It makes absolutely no difference in performance which modulation shift the manufacturer uses. What you do need to know is: Futaba and Hitec are negative shift, JR and Airtronnics use positive shift. Tx's and Rx's that are not of the same shift are not compatable. All companys that sell aftermarket Rx's make them available in both shifts and some have rx models that are selectable to funtion with any FM Tx. Additionally most modern computer Tx's have a shift select feature to allow them to funtion with any FM Rx. Your Conquest does not have this feature.

2. The high/low band thing applies to Futaba RX's and only Futaba Rx's. This is not a regulatory thing it is because of Futabas method of center tuning their Rx's to either the upper or lower half of the band. Once agine it is Futabas attempt to force you to buy more products. With all other modern brands you can freely use any channel from top to bottom of the band.
As the guys have mentioned above in the US it is illegal for the user to change crystals in a non module/synth TX without a retuning. However you can change RX crystals all you want.

3. Yes a single conversion Rx will work with your Conquest as long as it is of the same modulation shift (positive/negative) and if your TX is a FM conquest then of course the Rx must be FM. Single, dual conversion just refers to the the filtering methods used by the manufacturer.

4. I have no idea where to buy GWS. Do a search.

John

milto

My Feedback: (1)

Hey THANKS everyone, great info and much appreciated. I have a lot to learn.
Milt

DBCherry

My Feedback: (4)

Nice, concise response John.

Milt,
As John said, a single conversion, negative shift Rx (GWS or any other) will work with your Futaba conquest Tx. However, if you fly with other flyers I'd highly recommend staying away from single conversion.

Again, as John stated, single conversion refers to the filtering of the Rx, and single conversion Rx will not filter out signals from adjacent channels. They are also more prone to getting "hit" by things like pager signals, which occupay frequencies between our RC frequencies.

If you fly alone you can try the GWS. I have had one in a Park Flyer thst I mess around with and it's been okay when I'm alone. It's an okay deal for $28 with crystal in this application. I wouldn't risk a high value plane to one though.

Hope that helps.
Dennis-

Geistware

My Feedback: (16)

Milt, Here are the basics. Futaba transmitter and receivers work on negative shift. Futaba splits their channels from 11-35 and 36-60 so it is the low channels or high channels. The rest will be a matter of preference.

SlickCE

I believe he should go to the Torrey Pines page and read the " Everything you never wanted to know about Radio's" closely, matter of fact I think I will again, because I plainly remember some section of it mentioning Radio's mixing the - shift signal with the + shift signal and that the resulting frequency transmitted will cause major problems...

JohnBuckner

My Feedback: (1)

Grant I suspect what you are talking about is 3d order intermodulation which was a distinct problem with old wideband AM Tx's and this has nothing to do with modulation shift. All Tx's will have either positive or negative shift and we are fortunate today that the manufacturers have finally realized that the consumer wants the ability to use other TX, Rx's of other 'shifts' and the ability to select one or the other for different Rx's or selectable Rx's for other Tx's without that feature.

That ability in either a Rx or Tx in no way affects the performance of either. Virtually any new computer Tx hitting the market will have to have that ability to survive in the market.

John

David Cutler

This may well be so, but my guess is the original questioner understood Woodsy's response better then yours, (although, I concede, his knowledge on the whole subject doesn't look as impressive as yours) and ended up with a better understanding about what's really going on as a result.

-David C.

SlickCE

The problem I was referring to occurs with FM Dual Conversion Receivers. You can find it by going to the Torrey Pines Gulls Radio Reference and reading the Dual conversion section of the page. It talks some about Dual Conversion + and - shifting and problems you may encounter with it.

Actually, now that I reread it, the problem would be with attempting to use FM without Dual conversion I believe.