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receivers AN-GRC9




 
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PA0NVD
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Nico and Chappie (Chappie is the dog...)


« on: November 18, 2018, 12:30:52 PM »

Waiting for the tables for my shack, I couldn't sit down and started revising 3 receivers of the GRC9's. I have two complete sets and a loose receiver.
After mounting a few cells of 9 Volts batteries inside the negative supply batteries inside the receivers, just did switch them on. Surprise, they all worked directly. The only problem I noticed was that the sliders of the volume potmeters did not make good contact , but a little spray did solve that.
So next the alignment. And an other surprise, for all 3 receivers hardly necessary, they still were almost smack on after more than 50 years. Also, no tube change required.  Grin
Really nice little receivers, very well made!!
When the shack is ready, it is time to revise the transmitters and the LV80 and two DY88,s I have 3 of those powersupplies, so one will be modified to run at 115 VAC
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WA1LGQ
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« Reply #1 on: November 20, 2018, 12:25:17 PM »

Nice job. I have one complete unit and one loose receiver. Both have homebrew power supplies. I don't get good positive going modulation on the tx for some reason. Maybe about 50%. Negative is good. Have some accessories for it. the whip ant set with case and radio mount, ground screen wires with  spool and field strength meter. Fun stuff.
Larry
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PA0NVD
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Nico and Chappie (Chappie is the dog...)


« Reply #2 on: November 20, 2018, 03:08:09 PM »

Indeed fun stuff Larry
The modulation is quite dependent of the load of the final, not uncommon for modulation at the third grid. The T1154 transmitter suffers from that problem as well. If you load too much, no good positive modulation. The output is quite limited at AM, the book says it is 7 Watts for AM. But it also depends upon the state of the final tube the 2E22. A fresh tube may improve the modulation as well.
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WA1LGQ
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« Reply #3 on: November 21, 2018, 09:10:29 AM »

Oh yes, the loading. I will try that and watch the scope while talking into the hifi T-17. I forgot about that. I have another 2E22 if needed too.
Larry
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PA0NVD
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Nico and Chappie (Chappie is the dog...)


« Reply #4 on: November 21, 2018, 06:43:22 PM »

Please keep me posted with the results, I have to do the same when the shack is ready...
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SM6OID
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« Reply #5 on: November 27, 2018, 11:42:32 AM »

Hi!
All this GRC-9 talk made med curious about modulation pattern. So, brougt the scope and started or tried to start the Angry nine... It was a no go situation. Problem traced to the power cable, all fine on the outside completly rotten on the inside, so... I will have arrange with a new cable. Wish me luck...
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PA0NVD
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Nico and Chappie (Chappie is the dog...)


« Reply #6 on: November 27, 2018, 01:21:12 PM »

And those cables are not very abundant.. Cry
But you have the connectors, so you always can make new ones.
Wish you luck...
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WA1LGQ
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« Reply #7 on: November 27, 2018, 07:09:45 PM »

Sorry about the cable rot. But just make a new one with the connectors. They are hard to find. I made my own cable some years ago after I found a connector at a hamfest. I never found a power supply for it, so I built my own also. So I went through my GRC-9 this weekend and got it up to working condition again. The bandswitch in the receiver needed cleaning, and the dial tracking is not very good, so I re calibrated the rx to be fairly close in the ham bands. The transmitter puts out good power, but the modulation is still not good in the positive direction for some reason. Adjusting the loading made no difference. I installed a cable to connect a Heathkit Q multiplier at one time and it is much better on cw now.
LB
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PA0NVD
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Nico and Chappie (Chappie is the dog...)


« Reply #8 on: November 27, 2018, 08:20:22 PM »

When my shack is ready, I will revise my GRC9 as well and keep you posted about the results.
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AJ1G
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« Reply #9 on: November 29, 2018, 06:36:00 AM »

I recall someone had discussed several mods to the GRC-9, perhaps WU2D, that addressed transmitter chirp reduction on CW and improving the positve modulation peaks. Most likely was in ER magazine.  Was that you Mike?
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Chris, AJ1G
Stonington, CT
PA0NVD
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Nico and Chappie (Chappie is the dog...)


« Reply #10 on: December 04, 2018, 05:20:11 PM »

I did test the modulation of my AN-GRC9 and got the same results. Upto 50% modulation it looks real nice, If more, the positive doesn't increase much. At 90% negative, the positive is approx 60%. More modulation results in both negative and positive soft clipping
On the low power setting, the modulation is worse and there is distortion above 50%
Time to open the set and start measuring......
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