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Old 2nd Jan 2022, 4:24 pm   #41
G6Tanuki
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Default Re: FT-480R woes

_ALLEGEDLY_ the same Mitsubishi thick-film PA block was used in some "KEY" [KDK] high-band VHF mobile radios in the 1980s/1990s - though there they were biased for Class-C FM service.

Key radios often appear in the 'three for a fiver' piles of old PMR stuff or the bring&buy at radio-rallies - might be a path worth investigating when rallies start up again in the spring??
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Old 4th Jan 2022, 11:18 pm   #42
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Default Re: FT-480R woes

Hi
I do have a Motorola 74N10 RF power module but I cannot find a scrap of data on it.
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Old 5th Jan 2022, 1:14 am   #43
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Default Re: FT-480R woes

Motorola RF power division as-was is in a bit of a mixed-up condition.

Philips spun out their semiconductor side as NXP (but retained a lot of stock)
Motorola had spun out their basic semiconductor division as ON semiconductor, and their whizzier semiconductor division as Freescale. They kept the cellphone stuff.

NXP saw an opportunity and bought the RF semiconductor arm of Freescale.

Enter the US government, who decided that NXP now owned far too much of the RF power semiconductor market - heavily used by US military and government systems. NXP were told to get rid of either the old Motorola line or the old Philips line.

They reckoned the Freescale/Motorola product line was more modern, more coherent and a better bet for the future.

So NXP sold the once-Philips RF transistor division and the plant at Nijmengen to a Chinese consortium.

NXP operate the Motorola/Freescale product line from the plant just outside Phoenix, Arizona..... Under the brand name 'NXP'

So if you want data on old Motorola parts, it's NXP now, but you may be less likely to be told 'We have nothing' if you talk to them in Phoenix, not Europe.

DAvid

Oh, the Chinese consortium owning the old Philips line, trade as 'Ampleon'
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Old 5th Jan 2022, 2:55 am   #44
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Default Re: FT-480R woes

Quote:
Originally Posted by murphyv310 View Post
Hi
I do have a Motorola 74N10 RF power module but I cannot find a scrap of data on it.
They were also made by Toshiba and yes the data is very hard to come by.

Now, the MHW806 is the same case style and more than likely the same connections so the attached datasheet might help you play with it.

There is some limited 74N09 info floating around that marks it as a 100-900MHz RF Module so the 74N10 is likely to be similar, possibly just a different power out level.
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File Type: pdf MHW806.pdf (468.8 KB, 46 views)
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Old 6th Jan 2022, 10:35 am   #45
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Default Re: FT-480R woes

Just tried to call Vincent in I-Q designs on the phone number given, not recognized, shame, he must have moved, no results with that name on internet.
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Old 8th Jan 2022, 10:14 pm   #46
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Quote:
Originally Posted by g0hze snowy View Post
Just tried to call Vincent in I-Q designs on the phone number given, not recognized, shame, he must have moved, no results with that name on internet.
Snowy
Hi.
I've popped you a PM with his email address.
Hope that helps.
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Old 12th Jan 2022, 9:18 pm   #47
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Default Re: FT-480R woes

I've been trying other methods of making up a suitable PA. I'm thinking of utilising the circuit from the FT-290R. It has 2.5 Watts and is transistorised rather than a thick film module.
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Old 13th Jan 2022, 2:28 am   #48
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Default Re: FT-480R woes

The '290 PA should do about 5W if you ditch the whip antenna and all the matching stuff associated with it.
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Old 13th Jan 2022, 11:44 am   #49
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Default Re: FT-480R woes

Extrapolating from that, the official 2m clip-on linear amplifier for the FT290R2, (the FL2025) produced ~25W from 3W in, and I think that is also a discrete circuit although it most likely uses an obsolete PA transistor.

It might be worth studying the circuit for the FL-2025 at least.

Edit: Ah, no, I'm wrong, it uses an 'M' series PA module. (M57727).
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Old 16th Jan 2022, 10:34 am   #50
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Default Re: FT-480R woes

Hi.
Yesterday I did some more experiments with the PA. I swapped over the PLL board to ensure I had sufficient drive to do a proper test (although the PLL less the 63.9151mhz crystal works to an extent the output is low) I added a 2SC1972 as an output this along with an extra drive stage gave 14 Watts of clean RF. I was rather surprised TBH. later I removed the extra drive stage and this resulted in 2.2 Watts at 145.450Mhz into a dummy load, just about where I wanted it for QRP operation. So now all I want is the 63.9151mhz crystal to complete the work, another six to seven weeks wait for it though.
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Old 22nd Jan 2022, 11:25 pm   #51
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Default Re: FT-480R woes

Hi
I decided to feed in 63.9151mhz into the crystal oscillator circuit from my Nano VNA all locked up beautifully and surprisingly accurate, no 10Hz steps of course but all well. A solid 2.2 Watts on FM and 10 Watts peak on SSB. Modulation is excellent on both modes. Will need to sort out the tone burst as it's not switching off. I'm going to build a CTCSS encoder for this one and the end result will mean it's going to be fitted in the dash of the car for mobile use. This has been a great learning curve for these radios. Just another 5 weeks and I'll have the crystal all being well.
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Old 29th Jan 2022, 12:05 am   #52
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Default Re: FT-480R woes

My home made PA stage is prone to parasitic oscillation. I'm rebuilding it with better screening, layout and ferrite beads where necessary.

In fact I have now got two FT-480R transceivers that work very well with the last one now all set up, a mammoth task but the radio is really good.
So the first one is essentially the one that needs the crystal and has the home made PA stage. David's (Radio Wrangler) and the latest one are now working 100%.
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Old 18th Feb 2022, 8:08 pm   #53
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Default Re: FT-480R woes

Hi.
Some very good news. The 63.9151 Mhz Crystal has been dispatched. Watch this space for the result.
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Old 21st Feb 2022, 11:57 pm   #54
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Default Re: FT-480R woes

Hi.
The crystal arrived today and guess what? No oscillation! Didn't get a chance to find out why. The interesting thing is the only issue previously was the leg of the old crystal was corroded right through and fell apart. I can only think that there is a new fault to investigate. Hopefully get a bit of time tomorrow.
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Old 22nd Feb 2022, 12:13 am   #55
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Default Re: FT-480R woes

Crystal oscillator circuits have to be designed around the motional inductance and case capacitance of the crystal. Being a wide-ish VXO that circuit is likely to be somewhat peculiar. To get widest pulling, you want the crystal cut to the lowest overtone number.

Traditionally, ordinaly league crystal manufacturers don't like making anything thinner than a 20MHz fundamental, which translates to a 60MHz third overtone and a 100MHz 5th. They will push it to 30MHz fundamental mode (90 3rd, 150MHz 5th) but that's about it.

Why is overtone number so important? The pulling range of a crystal in parts per million falls, inversely proportional to the SQUARE of the overtone number. So for wide pulling, where you have the budget and space, you use a fundamental VXO, and a chain of multipliers. Some precision reference xtal oscillators employ low frequency overtone quartz to use the reduction in pullability to make it less sensitive to drift in circuit values.

David
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Old 22nd Feb 2022, 3:37 pm   #56
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Default Re: FT-480R woes

Does the above mean you think the new crystal may not have been made to the correct spec?

The way to be sure, since murphyv310 has more than one of these, is to put the new crystal into another set to see if it works there, and also put an original crystal from another set into this set to see if it fixes this set's problem.
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Old 22nd Feb 2022, 3:58 pm   #57
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Default Re: FT-480R woes

Hi.
Did some checks today. Another sets crystal works OK and the new one doesn't in the other set. Fiddling with an extra cap of 47pf across the choke L10 on the emitter and it will run but off frequency. So it looks as if the crystal is the wrong spec.
I'm about to give up on this.
I've added the circuit for some thoughts.
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Old 22nd Feb 2022, 6:37 pm   #58
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Default Re: FT-480R woes

I'm not sure anyone outside of Yaesu will know the full spec of that crystal. It is a very specialised application and engineering for pullability is a bit of a black art, especially for a VHF crystal.

With an ordinary crystal there is reliance on parameters beyond the frequency stamped on the can, and even with good guesses you often need to fiddle with some values to get it to start oscillating. A few iterations may be needed to get it on the right frequency. Going for a VCXO with fairly wide pulling range is a significantly more difficult task.

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Old 23rd Feb 2022, 10:57 am   #59
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Default Re: FT-480R woes

Hi.
Vince has double checked with the factory and confirmed it is to the Yaesu spec as they have the full details. So the issue is the crystal has been fitted, soldered in and excess from the legs snipped off so essentially now a used part, the money flushed down the pan. I can make it run by changing values but it's off frequency by around 10khz just like David thought.
Oh well you live and learn. Not been a great few weeks with a few disasters.
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Old 23rd Feb 2022, 11:05 am   #60
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Default Re: FT-480R woes

Probably not much help to the OP now, but the company I used to deal with (over the years many 100's of crystals for our police and fire held-helds) always asked for the relevant part of the radio's schematic if the crystal specification wasn't 100% clear.

In doing this, I never had any problems with non working crystals.

Just my two cents worth.
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