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Re: TRX1 PA Board

Marc, The point is that you should turn the bias trimmers to minimum voltage before powering the PA. Pse measure the resistance from gates (TR1, TR2, TR3) to GND and adjust the corresponding bias trimmers until ohm meter reading is indicating lower than few hundred ohms. You can use any GND joint fo...
by OH7SV
21 Nov 2012 18:15
 
Forum: Juma Discussion
Topic: TRX1 PA Board
Replies: 10
Views: 11801

Re: TRX2 general TX coverage

Edgar, JUMA TRX2 and TRX2A standard firmware in is not limiting TX frequency coverage. You can transmit on any frequency from 1.5MHz to 30MHz. Note that the PA low-pass filters are optimized for ham bands 1.8MHz - 28MHz. This may mean more harmonics on non ham frequencies especially in low edge of t...
by OH7SV
19 Nov 2012 20:52
 
Forum: Juma Discussion
Topic: TRX2 general TX coverage
Replies: 2
Views: 4684

Re: PA100-D with an Elecraft KX3

David,

You may try different drive levels (2.5W-10W) from KX3 and adjust JUMA PA100 gain accordingly to get desired power ouput.
I think this way you will get proper operation of the frequency detection also on 15m and 17m.

When you have tested, pse let me know your findings.

73 Matti OH7SV
by OH7SV
22 Aug 2012 02:37
 
Forum: Juma Discussion
Topic: PA100-D with an Elecraft KX3
Replies: 6
Views: 12876

Re: TRX2 1st filter and sidetone level

Hello Laurent, You are right that the 1st filter is a "roofing" filter which is in the AGC loop. We know the properties of the 1st filter. It is compromize of selectivity and noise. Noise is the reason for its response because sharp active filters are easily bad noise generators. I have be...
by OH7SV
19 Aug 2012 05:53
 
Forum: Juma Discussion
Topic: TRX2 More narrow filter
Replies: 5
Views: 11885

Re: PA100 PA Current Resistor

Dave,

The R7 resistor is single 0.005 ohm current sense resistor. The two 0.010 ohm resitors are remains when 0.005 ohm was not available. You can keep the two 0.010 ohms in parallel.

73 Matti OH7SV
by OH7SV
19 Aug 2012 05:39
 
Forum: Juma Discussion
Topic: PA100 PA Current Resistor
Replies: 1
Views: 4521

Re: JUMA PA100D 3rd order distortion

Dave & co,

See the PA100 IMD measurements in Juma pages
http://www.jumaradio.com/juma-pa100/jum ... ments.html

73 Matti OH7SV
by OH7SV
19 Aug 2012 05:33
 
Forum: Juma Discussion
Topic: JUMA PA100D 3rd order distortion
Replies: 1
Views: 4041

Re: PA100D "total disaster"

Björn, Sorry to hear that. But don't worry, every PA100 will function properly when everything is built in a correct way. If you feel that you can not find the problem by your self, pse contact Juma Community hams. They will help you. See this link http://www.jumaradio.com/juma/juma-community.html 7...
by OH7SV
24 Apr 2012 17:42
 
Forum: Juma Discussion
Topic: PA100D "total disaster"
Replies: 2
Views: 5129

Re: Possible mistake in TRX2 Main Board voltage table

Oh yes,
It seems there is a mistake during CW transmit state.
I will correct that.

73 Matti OH7SV
by OH7SV
25 Mar 2012 07:54
 
Forum: Juma Discussion
Topic: Possible mistake in TRX2 Main Board voltage table
Replies: 3
Views: 6168

JUMA PA1000 weight reduced from 14 kg to 5 kg

Here are the original heavy weight mains transformers. juma-pa1000-mains-transformers.jpg This is the prototype with the light weight resonance switching power supply. The power supply weights only 0.8kg. Note also the handle on the right side. juma-pa1000-SMPS.jpg The first tests have been done and...
by OH7SV
24 Mar 2012 17:39
 
Forum: Juma Discussion
Topic: JUMA PA1000 Linear Amplifier
Replies: 50
Views: 197589

Re: Possible mistake in TRX2 Main Board voltage table

Jan, You are right, IC2 pin 15 should be zero in CW during transmit state. This is not a mistake because all the voltages in the "Main Board DC voltage table" are in Receive state, Mode LSB. The IC2 pin 15 selects the TX muxer to CW during transmit. Main Board DC voltage table http://www.j...
by OH7SV
24 Mar 2012 15:50
 
Forum: Juma Discussion
Topic: Possible mistake in TRX2 Main Board voltage table
Replies: 3
Views: 6168
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