Using a receiver with the "wrong" crystal

Joe,

I did what should probably have been done in the first place and asked Tony Stillman of Radio South if he would comment. Basically I explained to him the question of mixing low/high receivers and crystals. And asked if he or one of his techs could provide some info as to the pros and cons of doing such a thing? I further stated that many responses here claim that as long as it range checks OK there's no problem.

His response was, "Yes, that is the real test. If the range check is good, it is fine."

So there you all have it. Go forth and fly! :)

Chuck

Does this mean the older Futaba R127DF receiver doesn't use an RF stage before going to the mixer, but the new Futaba R127DF has been changed to include the RF stage? My old R127DF was bought several years before they started seperating them into high/low band.

Agreed

Alan T. Alan's Hobby, Model & RC Links

Yes I can! I still fly with Futaba FG series AM radios! My club requires That I use 3 frequency pins ( the channel I'm on and the two adjoining ones) never had a problem yet (and never will). LONG LIVE FUTABA FG AM RADIOS! Steve

Mike wrote:

Steve,

Only three pins huh?

Our club used to have a member with a really old Kraft AM transmitter. When asked what channel he was on his response was: "All of them".

Mike

If you are doing that in the US, you are breaking federal law.

That beats flying, landing, and re-tuning the reeds every time. :) Dr.1 Driver "There's a Hun in the sun!"

LOL. I guess it's a good thing I buy Hitec and Berg these days. :)

Back in those days, your set came with both transmitter and receiver crystals. Your instruction manual advised you to return the gear for retuning should you wish to change channels. Receivers weren't sold without crystals. In fact, only the transmitter tuning was critical. On most bands, Futaba just installed the proper crystal without any special tuning. On 72 MHz, they made their dual conversion receivers in high-band or low band batches and put the proper crystals in them. They still do that today. The difference is that you can now purchase a receiver without a crystal installed.

You are unlikely to have range problems when using a low band Xtal in a high band receiver or vice versa unless the current tuning of the receiver has drifted and the mismatch is large. In such cases, Futaba service can peak your receiver to a specific channel.

Jim - AMA 501383 (remove .nospam to reply)

Tim wrote:

Recently, they have started labeling them. In the past, only the factory could tell. If you purchased the receiver new, then you can be certain that it is either high band or low band by the Xtal which was originally installed. If you bought a used receiver, than all bets are off. It might be the correct band, it might have been peaked for the Xtal installed or it might have been changed to another channel without retuning.

Since most of the 72 MHz. dual conversion receivers aren't marked, what is really important is that you get a good range check. If the range check is good, then don't worry. It usually isn't a problem.

Jim - AMA 501383 (remove .nospam to reply)

ZEMSKI wrote:

No, The R127DF has always been made either high or low band. Only recently have they actually been sold that way.

Jim - AMA 501383 (remove .nospam to reply)

Actually, it means that Futaba provides a very selective RF filter before the first mixer. Hitec chooses not to. Both make fine receivers.

Jim - AMA 501383 (remove .nospam to reply)

Only very stripped down parkfly stuff doesn't use at least one RF coil to improve image rejection. I suspect older recievers don't have as high Q front ends as more modern 'hi-lo' stuff.

Or they have much better front ends.

Sounds like me in the days when I had a 3.5W 27Mhz transmitter and super regen rx'es.

NO ONE interfered with MY radio.

I could control any other superegen in the sky, and did on one occasion to retrieve someones model when it had flown beyind teh range of his OS pixie set (thnk it was that anyway. LONG time ago)

The bloody superhet chequebook modellers used to never give you time to fkly superegen, so we just built or own sets and flew on the other hill.

Of course, some of us preferred to fly LEGALLY. Sounds like the many CB'ers who were running 400W linear amplifiers. Dr.1 Driver "There's a Hun in the sun!"

True, they are good, hence the smiley above. I have two Futaba receivers that came with my two transmitters and both of them have been flawless except that time I had the little TV transmitter mounted too close. ;)

I buy Hitec and Berg receivers because they are considerably cheaper and work just as good as my Futaba receivers.

And like the CB's that blasted into the living room through the old console TV, you could pull an "Outer Limits"...we control the vertical...we control the horizontal...assuming it was at least a two channel Tx! ;)