[Central-Electronics] Fwd: Re: 6550

Gordon gordon at n6wk.com
Thu Jul 25 16:27:16 EDT 2013 

Hmm, I also see that the different chokes have different Q's and also 
different Resonant Frequencies.. Now I'm lost as to which one to 
0rder.... :-(

HELP !!!  PLEASE !!


&3,
Gordon


On 7/25/2013 1:22 PM, Gordon wrote:
> In agree Jim,
>  I am getting ready to order a new Choke to replace RFC-1 but not sure 
> of what Current rating I should order.
> Any of the Guru's on the 100V have a clue? I have found sources for 
> 22uH, so that doesn't seem to be an issue.
>   Jim, I have done the Carrier Null and I can get it down almost 
> nothing on the meter.
> Right Now I am replacing everything under the Tube Sockets for the 
> Finals section. I am about half done.
> I did discover an unsoldered connection on one of the tube terminals 
> for the ground of C412.
>
> 73,
> Gordon
> N6WK
>
> On 7/25/2013 12:55 PM, Jim Candela wrote:
>>
>> Gordon,
>>
>>    I see you were up late tinkering. So getting zilch to 75 watts is 
>> a big deal! You might want to enjoy the moment before proceeding. I 
>> bet that RF choke, RFC1 is damaged, and a vital part of the circuitry 
>> since it seems odd to me to use a choke that low in inductance. A 
>> quick scribble suggests that 23uh on 80M has about 550 ohms inductive 
>> reactance. Perhaps that amount of reactance compensates for something 
>> that the broadband couplers need.
>>
>>    Maybe you can build up something with similar characteristics? A 
>> DC short in that output circuit might be required to make the power 
>> meter behave. Or possibly, the power you see with no drive could be 
>> the carrier null being a little off?
>>
>>    I was hoping the 100V/200V guru's would jump in here...This 20A 
>> guy is getting out of his element..
>>
>> Jim
>> WD5JKO
>>
>>
>> ________________________________
>>   From: Gordon <gordon at n6wk.com>
>> To: central-electronics at mailman.qth.net
>> Sent: Thursday, July 25, 2013 12:04 AM
>> Subject: [Central-Electronics] Fwd: Re:  6550
>>
>>
>>
>> Jim,
>>    I removed RFC-1 and now I get 75 watts out on 75 meters. but as I go
>> higher, each band puts out a little less.
>> I think I should be looking for a bad Cap at this point, as removing the
>> inductance made more power.
>> Another Question, What is up with the little Coax Capacitor thing coming
>> off the Band coupler Wafer?
>>      I think Tomorrow, I am going to strip everything out from below the
>> Finals cage and replace each and every part.
>> Another clue might be that my Watts meter shows a reading in transmit,
>> even with the Carrier and Power control at fully counterclockwise, and
>> the Pot for the Watts turned down as far as it will go.
>> I should not be showing anything when there is No output and all
>> controls at minimum. I even get a Watts reading in SSB with No carrier
>> and no Mic connected...
>>
>> 73,
>> Gordon
>> N6WK
>>
>> On 7/24/2013 7:23 PM, Jim Candela wrote:
>>> Gordon,
>>>
>>> "At first I thought it might be the RFC-1,  mine shows 2.3uH when 
>>> measured out of circuit"
>>>
>>>      Looking at the schematic, RFC-1 says .022mh. This converted to 
>>> uh is 22uh. I'd remove that part temporally and run up the drive. 
>>> This might explain why you have more power output with increasing 
>>> frequency.
>>>
>>> Jim
>>> WD5JKO
>>>
>>>
>>> ________________________________
>>>     From: Gordon <gordon at n6wk.com>
>>> To: central-electronics at mailman.qth.net
>>> Sent: Wednesday, July 24, 2013 6:25 PM
>>> Subject: Re: [Central-Electronics] 6550
>>>
>>>
>>> Hi George and the Group,
>>> George, I have double checked everything you mentioned..Same results.
>>>      I tried the new tubes, and as everyone said,  They are NOT the 
>>> problem.
>>> I do have a question though. If I disconnect the Coax from the last
>>> wafer that goes to the RF Sampling circuit and the SO-239 connector,
>>> Connect my MFJ-259 to the loose end of the Coax  , with a 50 Ohm 
>>> load in
>>> the SO-239, shouldn't the MFJ-259 show 50 ohms? Mine is no where 
>>> near 50
>>> ohms. If I check the dummy load by itself, it is exactly 50 ohms.
>>> The only thing on that Coax is the Amps Sampler for the RF output and
>>> the SO-239. At first I thought it might be the RFC-1,  mine shows 2.3uH
>>> when measured out of circuit, So it appears to be good.
>>> I also noticed that the Neutralizing Cap is NOT shown on the 100V
>>> Schematic I have in front of me.
>>>
>>> Gordon
>>> N6WK
>>>
>>>
>>>
>>> On 7/24/2013 9:48 AM, George Maier wrote:
>>>> Hi Gordon:
>>>>
>>>> Great job on the 100V; glad to see so much enthusiasm for such a 
>>>> worthwhile
>>>> project.   Not sure why you are having the RF O/P problems, but 
>>>> your coupler
>>>> sequence is correct, and the voltages all seem within limits.  Not 
>>>> sure what
>>>> you've done electrically, but here are a few simple things you may 
>>>> want to
>>>> consider, if you have not already addressed them.  If you have, please
>>>> ignore my drivel:
>>>>
>>>> 1 - Remove each coupler and apply a high quality contact cleaner to 
>>>> the base
>>>> pins and the tap connectors; i.e. - Caig Pro-Gol applied with a 
>>>> q-tip or
>>>> Caig pen.
>>>> 2 - Same exercise for all of the of the lower stage coil banks, 
>>>> which are
>>>> all removable.
>>>> 3 - Be sure to replace the 100 mf - 15V cap (C418) across the PA 
>>>> screen over
>>>> current relay; they're almost always bad. Also, burnish the relay 
>>>> contacts.
>>>> 4 - Check the 10 Ohm resistor (R450) that is in series with the power
>>>> control,  to make sure it's not open., and also the rest of the 
>>>> surrounding
>>>> connections and circuitry.
>>>> 5 - Remove all of the chassis interconnecting plugs (carefully) and 
>>>> clean
>>>> them with Pro-gold also.
>>>>
>>>> Those steps should help to eliminate any flaky stuff, unless of 
>>>> course you
>>>> do have bad tubes along the line.  Generally, I agree with the 
>>>> other folks
>>>> here, that the PA tubes do not usually fail totally, but hey, it's 
>>>> certainly
>>>> possible.
>>>>
>>>> Keep chugging, Gordon; you'll get there!
>>>>
>>>> 73, George - W1LSB
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: central-electronics-bounces at mailman.qth.net
>>>> [mailto:central-electronics-bounces at mailman.qth.net] On Behalf Of 
>>>> Gordon
>>>> Sent: Tuesday, July 23, 2013 9:02 PM
>>>> To: central-electronics at mailman.qth.net
>>>> Subject: Re: [Central-Electronics] 6550
>>>>
>>>> I am still fighting the no to Low output on my CE-100V.
>>>> I have ordered new 6550 tubes, but now I am thinking they are nt the
>>>> problem. The tube tester shows both as very strong I am now 
>>>> wondering if
>>>> someone has mixed up the Broadband output Coils.
>>>> Can anyone tell me what color is correct for each band?
>>>> I have Red for 80, yellow for 40, green for 20, blue for 15 and 
>>>> slate for 10
>>>>
>>>> Is this correct?
>>>> I have now discovered that I get more output as I move up in bands. 
>>>> I get a
>>>> whole 12 watts out on 20 and 15 meters..LOL Is there a way to test the
>>>> center Frequency of each of these broadband output coils?
>>>>
>>>> Thanks,
>>>> Gordon
>>>> N6WK
>>>>
>>>>
>>>>
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