TS850 FM power output - UK Vintage Radio Repair and Restoration Discussion Forum

Peter.N. · 12th Jun 2011, 9:23 pm

Hi folks

I have just sold my TS850 and the buyer is complaining that although SSB output is around 100 watts he is only getting 25w on FM, to be perfectly honest I didn't even know that it had FM.

Can anyone suggest why and what can be done about it.

Thanks

Peter

g4aaw pete · 12th Jun 2011, 10:02 pm

Hello Peter

Firstly, I’d be interested to know how accurately the power was measured on FM.
Secondly, the user guide spec seems a bit doubtful to me. This states:
100w max on SSB,CW & FM
40w max on AM
It seems to me that an FM transmission represents 100% duty cycle on the finals, so I’d expect it to be rated at 40w, as with AM.

Regards
Pete

Peter.N. · 13th Jun 2011, 12:16 am

Hi Pete

Well I would have thought that, 100 watts of continious carrier is going to generate a lot of heat and use a lot of power, but the manual says that's what it is supposed to be. He was apparantly testing it by tuning up on FM and then switching to SSB, presumably the power meter was showing 25 watts FM and then 100 when switched to SSB.

Peter

Sean Williams · 13th Jun 2011, 7:28 am

Hmm, a few questions....

What is the buyer using for a power meter

What sort of load is he using

Is the power supply rated to supply the full load current

Is the auto ATU in use?

It is very odd to be able to acheive full output on SSB, and then low OP, on a continuous carrier mode.

Ask him to test it in CW as well.

HTH
Sean

neon indicator · 13th Jun 2011, 10:58 am

AM is essentially 1/4 of CW power when no modulation as carrier has to sit at 1/2 voltage.

Sustained key down CW and FM power should be equal. FM doesn't need linear. It's CW with a wobble

SSB peak power can't really exceed CW/FM power, though on valve P.A. it may due to unregulated HT able to sustain speech peaks at higher power than FM or CW. SSB with a whistle or tuning tone is typically equal to CW or FM on transistor or valve PA.

Any rig using SSB mode and keying an audio tone for CW gives same max power on SSB, FM and CW. The advantage of SSB + tone for CW is less key click, often then there is an adjustable delay for TX to drop back to receive in space between dot/dash to allow "break in mode" operation.

If there is a mismatch the protection part of ALC loop will wind power back on CW key down and on FM. But if your speech peaks may be to fast for ALC / Protection circuit to detect.

On the TS850 there is a procedure where you can terminate in 100 Ohms instead of 50 Ohms and adjust the sensitivity of the protection circuit. Or Open circuit at low power. Certainly one TS850 I aligned was doing something like this on 50 Ohm dummy load! If you hold key down the power drops to FM level if this is the case, but on short dit dah you get full power as there is a time constant on the ALC and reverse SWR detector.

If it was fine before sale, then it's not misalignment but "normal" behaviour for these rigs when mis-matched. If power drops with a continuous whistle into Mic on SSB it confirms my theory (of either protection over sensitive or mismatch).

Peter.N. · 13th Jun 2011, 5:58 pm

I have never used FM so I don't know. I was just hoping that there is someone else on here that has a TS850 and can verify the FM output on their radio.

Peter

neon indicator · 14th Jun 2011, 8:34 am

It's 100W on FM.

Skywave · 14th Jun 2011, 12:22 pm

Seems to me that the appropriate reply to the buyer is quite simple.

Ask him to verify that he is getting 100W output on C.W. Then, without making any changes to his set-up - including his test & measurement equipment - ask him what power output he gets when he switches to F.M. The resultant power indication should be the same - if all is well.

Al.

Peter.N. · 15th Jun 2011, 9:47 am

Hi Al

That's what he said he was doing, 100w on side band and only 25 when switched to FM. I have now got the radio back so it will be for sale again. I wouldn't have thought that many people would have used FM, I certainly didn't.

Thanks for all you comments folks.

Peter

neon indicator · 15th Jun 2011, 2:14 pm

Only on 10m repeater or illegal CB operation I'd think!

Skywave · 15th Jun 2011, 3:35 pm

Hi Peter,

When the buyer said that the power dropped between the two modes, what meter was he using? I certainly wouldn't rely on the meter in any rig when faced with such a disparity of this magnitude. And was this with the TX connected to a 50-ohm dummy load? Whenever I'm checking kit like this, I always connect it to a 'Bird Thru-Line' wattmeter and into a 500-watt 'Bird' 50-ohm dummy load. That way, I can rely on the measurement.

Hence, I simply have to ask: can you verify that the radio will indeed produce the specified 100-W output on FM? After all, you don't want to sell it (again) and have a repeat scenario!

Al.

Skywave · 15th Jun 2011, 3:38 pm

Quote:

Originally Posted by Peter.N.

I wouldn't have thought that many people would have used FM: I certainly didn't.
Peter

There is always the possibility of using it with a transverter to produce FM on a VHF / UHF band.

Al.

Peter.N. · 15th Jun 2011, 3:55 pm

Had not thought of that, didn't think people did that sort of thing any more. Presumably you can use it on 28 mhz.

The only thing in support of his argument is that he says it delivers 40 watt on AM as specified and he has tried it on several different antennas with the same result. The FM output is not listed seperatly in the manual its just listed in the 100w output group of modes. If AM is only 40 watts I would have thought that FM would have been similar. It's now for sale again so we will see what prospective purchasers think.

Peter

Skywave · 15th Jun 2011, 4:23 pm

Quote:

Originally Posted by Peter.N.

The only thing in support of his argument is that he says it delivers 40 watt on AM as specified and he has tried it on several different antennas with the same result.
Peter

Call me a fastidious old purist if you will, but that method: using antennas for loads and presumably relying on the front panel meter to give a measure of RF output is not one that I would ascribe much value to, let alone go back to the vendor with the complaint that he has made on the basis of the measurements thus obtained. There are just too many undeterminable variables with that method.
Ask yourself this: what method would have been used in the factory, at final test, to verify the RF power output? Certainly not the method that your buyer was using.

Anyway, with regards to this particular item, it's all academic now. Good luck next time!

Al.

Sean Williams · 15th Jun 2011, 5:43 pm

Your buyer is a blooming idiot!

You cannot check RF output into an flipping antenna....

Dear oh dear.....

Sean

neon indicator · 15th Jun 2011, 8:49 pm

The AM is maybe about 40W is with "typical" audio drive. It's 25W no audio modulation at "full power" or it's not adjusted right.

CW, FM and SSB with Tone for full power will all be exactly same power unless something is wrong. FM power level is same on no audio and max audio level. SSB power level is 0 to 100W depending on drive.

I use a 100W dummy load and separate external home brew meter (calibrated on 10W, 100W and 1000W scales with a Bird meter) for test/measurement.

12th Jun 2011, 9:23 pm	#1
Peter.N. Dekatron Join Date: Jul 2008 Location: Charmouth, Dorset, UK. Posts: 3,601	TS850 FM power output Hi folks I have just sold my TS850 and the buyer is complaining that although SSB output is around 100 watts he is only getting 25w on FM, to be perfectly honest I didn't even know that it had FM. Can anyone suggest why and what can be done about it. Thanks Peter

12th Jun 2011, 10:02 pm	#2
g4aaw pete Heptode Join Date: Jan 2008 Location: Birchington Kent, UK. Posts: 596	Re: TS850 FM power output Hello Peter Firstly, I’d be interested to know how accurately the power was measured on FM. Secondly, the user guide spec seems a bit doubtful to me. This states: 100w max on SSB,CW & FM 40w max on AM It seems to me that an FM transmission represents 100% duty cycle on the finals, so I’d expect it to be rated at 40w, as with AM. Regards Pete

13th Jun 2011, 12:16 am	#3
Peter.N. Dekatron Join Date: Jul 2008 Location: Charmouth, Dorset, UK. Posts: 3,601	Re: TS850 FM power output Hi Pete Well I would have thought that, 100 watts of continious carrier is going to generate a lot of heat and use a lot of power, but the manual says that's what it is supposed to be. He was apparantly testing it by tuning up on FM and then switching to SSB, presumably the power meter was showing 25 watts FM and then 100 when switched to SSB. Peter

13th Jun 2011, 7:28 am	#4
Sean Williams Dekatron Join Date: Feb 2005 Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW Posts: 3,518	Re: TS850 FM power output Hmm, a few questions.... What is the buyer using for a power meter What sort of load is he using Is the power supply rated to supply the full load current Is the auto ATU in use? It is very odd to be able to acheive full output on SSB, and then low OP, on a continuous carrier mode. Ask him to test it in CW as well. HTH Sean __________________ Engineers make things work and have spare bits when finished

13th Jun 2011, 10:58 am	#5
neon indicator Retired Dormant Member Join Date: Jun 2010 Location: Co. Limerick, Ireland. Posts: 1,183	Re: TS850 FM power output AM is essentially 1/4 of CW power when no modulation as carrier has to sit at 1/2 voltage. Sustained key down CW and FM power should be equal. FM doesn't need linear. It's CW with a wobble SSB peak power can't really exceed CW/FM power, though on valve P.A. it may due to unregulated HT able to sustain speech peaks at higher power than FM or CW. SSB with a whistle or tuning tone is typically equal to CW or FM on transistor or valve PA. Any rig using SSB mode and keying an audio tone for CW gives same max power on SSB, FM and CW. The advantage of SSB + tone for CW is less key click, often then there is an adjustable delay for TX to drop back to receive in space between dot/dash to allow "break in mode" operation. If there is a mismatch the protection part of ALC loop will wind power back on CW key down and on FM. But if your speech peaks may be to fast for ALC / Protection circuit to detect. On the TS850 there is a procedure where you can terminate in 100 Ohms instead of 50 Ohms and adjust the sensitivity of the protection circuit. Or Open circuit at low power. Certainly one TS850 I aligned was doing something like this on 50 Ohm dummy load! If you hold key down the power drops to FM level if this is the case, but on short dit dah you get full power as there is a time constant on the ALC and reverse SWR detector. If it was fine before sale, then it's not misalignment but "normal" behaviour for these rigs when mis-matched. If power drops with a continuous whistle into Mic on SSB it confirms my theory (of either protection over sensitive or mismatch).

13th Jun 2011, 5:58 pm	#6
Peter.N. Dekatron Join Date: Jul 2008 Location: Charmouth, Dorset, UK. Posts: 3,601	Re: TS850 FM power output I have never used FM so I don't know. I was just hoping that there is someone else on here that has a TS850 and can verify the FM output on their radio. Peter

14th Jun 2011, 8:34 am	#7
neon indicator Retired Dormant Member Join Date: Jun 2010 Location: Co. Limerick, Ireland. Posts: 1,183	Re: TS850 FM power output It's 100W on FM.

14th Jun 2011, 12:22 pm	#8
Skywave Rest in Peace Join Date: Jun 2006 Location: Chard, South Somerset, UK. Posts: 7,457	Re: TS850 FM power output Seems to me that the appropriate reply to the buyer is quite simple. Ask him to verify that he is getting 100W output on C.W. Then, without making any changes to his set-up - including his test & measurement equipment - ask him what power output he gets when he switches to F.M. The resultant power indication should be the same - if all is well. Al.

15th Jun 2011, 9:47 am	#9
Peter.N. Dekatron Join Date: Jul 2008 Location: Charmouth, Dorset, UK. Posts: 3,601	Re: TS850 FM power output Hi Al That's what he said he was doing, 100w on side band and only 25 when switched to FM. I have now got the radio back so it will be for sale again. I wouldn't have thought that many people would have used FM, I certainly didn't. Thanks for all you comments folks. Peter Last edited by Brian R Pateman; 15th Jun 2011 at 12:37 pm. Reason: FRC - Section C.

15th Jun 2011, 2:14 pm	#10
neon indicator Retired Dormant Member Join Date: Jun 2010 Location: Co. Limerick, Ireland. Posts: 1,183	Re: TS850 FM power output Only on 10m repeater or illegal CB operation I'd think!

15th Jun 2011, 3:35 pm	#11
Skywave Rest in Peace Join Date: Jun 2006 Location: Chard, South Somerset, UK. Posts: 7,457	Re: TS850 FM power output Hi Peter, When the buyer said that the power dropped between the two modes, what meter was he using? I certainly wouldn't rely on the meter in any rig when faced with such a disparity of this magnitude. And was this with the TX connected to a 50-ohm dummy load? Whenever I'm checking kit like this, I always connect it to a 'Bird Thru-Line' wattmeter and into a 500-watt 'Bird' 50-ohm dummy load. That way, I can rely on the measurement. Hence, I simply have to ask: can you verify that the radio will indeed produce the specified 100-W output on FM? After all, you don't want to sell it (again) and have a repeat scenario! Al.

15th Jun 2011, 3:55 pm	#13
Peter.N. Dekatron Join Date: Jul 2008 Location: Charmouth, Dorset, UK. Posts: 3,601	Re: TS850 FM power output Had not thought of that, didn't think people did that sort of thing any more. Presumably you can use it on 28 mhz. The only thing in support of his argument is that he says it delivers 40 watt on AM as specified and he has tried it on several different antennas with the same result. The FM output is not listed seperatly in the manual its just listed in the 100w output group of modes. If AM is only 40 watts I would have thought that FM would have been similar. It's now for sale again so we will see what prospective purchasers think. Peter Last edited by Station X; 15th Jun 2011 at 7:19 pm. Reason: FRC.

15th Jun 2011, 5:43 pm	#15
Sean Williams Dekatron Join Date: Feb 2005 Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW Posts: 3,518	Re: TS850 FM power output Your buyer is a blooming idiot! You cannot check RF output into an flipping antenna.... Dear oh dear..... Sean __________________ Engineers make things work and have spare bits when finished

15th Jun 2011, 8:49 pm	#16
neon indicator Retired Dormant Member Join Date: Jun 2010 Location: Co. Limerick, Ireland. Posts: 1,183	Re: TS850 FM power output The AM is maybe about 40W is with "typical" audio drive. It's 25W no audio modulation at "full power" or it's not adjusted right. CW, FM and SSB with Tone for full power will all be exactly same power unless something is wrong. FM power level is same on no audio and max audio level. SSB power level is 0 to 100W depending on drive. I use a 100W dummy load and separate external home brew meter (calibrated on 10W, 100W and 1000W scales with a Bird meter) for test/measurement.