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More testing on PA

Tim All Messages By This Member #33315 I have Dr. Bills PA and a similar (same finals) from 60dbm shop. Both on 13V same 0dB sweep from SA. I attached the 60dBm Schematic for reference. Here is Dr. Bills with 0dB in His with -10dB in, 60dbm shop amp 0dBin ? ? Amplifier_3_sch _1_.pdf Amplifier_3_sch _1_.pdf
Henning Weddig All Messages By This Member #33321 Tim, You plot shows some overdriving at low frequencies of either the Pa or the SA. So either increease the reference level to +20 dBm, or use a 10 dB attenautor at the SA?s input or lower the output of the TG by at least 10 dB. Henning Weddig DK5LV Am 31.03.2025 um 21:06 schrieb Tim via groups.io: toggle quoted message Show quoted text I have Dr. Bills PA and a similar (same finals) from 60dbm shop. Both on 13V same 0dB sweep from SA. I attached the 60dBm Schematic for reference. Here is Dr. Bills with 0dB in His with -10dB in, 60dbm shop amp 0dBin
Tim All Messages By This Member #33325 Tnx Henning ? SA was not overdriven, I did the 60dBM plot first and did not want to change anything. The low bands were 12W so exceeded scale. SA had a lot of headroom left, I had 40dB attenuator in line from PA to SA. You were quick to? see that shows you know your instrumentation well. ? Tim W4YN? ?
K9HZ All Messages By This Member #33326 开云体育 You have the compensation cap in place on the primary of T3? ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch – K9ZC Staunton, Illinois ? Owner – Operator Villa Grand Piton – J68HZ Soufriere, St. Lucia W.I. Rent it: ? Moderator: North American QRO Group at Groups.IO. Moderator: Amateur Radio Builders Group at Groups.IO. ? email:? bill@... ? ? toggle quoted message Show quoted text From: [email protected] <[email protected]> On Behalf Of Tim via groups.io Sent: Monday, March 31, 2025 2:06 PM To: [email protected] Subject: [SoftwareControlledHamRadio] More testing on PA ? I have Dr. Bills PA and a similar (same finals) from 60dbm shop. Both on 13V same 0dB sweep from SA. I attached the 60dBm Schematic for reference. Here is Dr. Bills with 0dB in His with -10dB in, 60dbm shop amp 0dBin ? ?
Tim All Messages By This Member #33327 Not at this time Tim
Tim All Messages By This Member #33342 On Wed, Apr 2, 2025 at 07:48 AM, K9HZ wrote: Dr. Bill Playing with compensation caps around 180-220 flattens out from 3-30Mhz I can't seem to get much gain past 35-40Mhz Still playing not that interested in 6M qrp? so not a big deal. ? Just curious on how Paul got his so flat out to 50Mhz. Tim? ? ?
K9HZ All Messages By This Member #33350 开云体育 I have four of the PA kits built here and I get a gain fluctuation of +0.2/-0.8 from 1-54 Mhz inclusive after a little tuning of the capacitor across the T3 primary.? You might check to make sure you got the right numbers of turns on T1, T2, and T3… More than one person has had trouble with that. ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch – K9ZC Staunton, Illinois ? Owner – Operator Villa Grand Piton – J68HZ Soufriere, St. Lucia W.I. Rent it: ? Moderator: North American QRO Group at Groups.IO. Moderator: Amateur Radio Builders Group at Groups.IO. ? email:? bill@... ? ? toggle quoted message Show quoted text From: [email protected] <[email protected]> On Behalf Of Tim via groups.io Sent: Thursday, April 3, 2025 7:46 PM To: [email protected] Subject: Re: [SoftwareControlledHamRadio] More testing on PA ? On Wed, Apr 2, 2025 at 07:48 AM, K9HZ wrote: Dr. Bill Playing with compensation caps around 180-220 flattens out from 3-30Mhz I can't seem to get much gain past 35-40Mhz Still playing not that interested in 6M qrp? so not a big deal. ? Just curious on how Paul got his so flat out to 50Mhz. Tim? ? ?
Tim All Messages By This Member #33366 I can see me messing up those? I will rewind for grins. Tim?
K9HZ All Messages By This Member #33368 开云体育 Yeah another mistake is pulling the wire so tight that is scrapes the enamel off the wire between turns and shorts them together.? I am guilty of doing that… ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch – K9ZC Staunton, Illinois ? Owner – Operator Villa Grand Piton – J68HZ Soufriere, St. Lucia W.I. Rent it: ? Moderator: North American QRO Group at Groups.IO. Moderator: Amateur Radio Builders Group at Groups.IO. ? email:? bill@... ? ? toggle quoted message Show quoted text From: [email protected] <[email protected]> On Behalf Of Tim via groups.io Sent: Saturday, April 5, 2025 12:53 PM To: [email protected] Subject: Re: [SoftwareControlledHamRadio] More testing on PA ? I can see me messing up those? I will rewind for grins. Tim?
Tim All Messages By This Member #33382 I rewound t1,2 and 3. Tested between each rewind, tuned out T3 was culprit, easiest to wind! Not sure what it was ,I may have had a solder bridge across C25 which on revised board is right next to center tap pad. I would suggest moving that if you revise board. Seems very easy to bridge when soldering center tap windings. 100pF across primary, 7 turns on L2 (enamel wire). I may play a bit with cap across primary but it looks so much nicer now I may just leave it alone! Tim?
Tim All Messages By This Member #33383 Better Scale
K9HZ All Messages By This Member #33384 开云体育 Yeah, that’s what mine looks like too. ??Glad you found the issue.? ?I’ve sold over 1,000 of those PA semi-kits now and I’ve only had three people have issues since I started selling them.? One was a power lead reversal (YIKES)… Its pretty simple… not much to go wrong. ? One thing on my to-do list is to put together a list of test points with voltages and wave forms for all of the T41 boards… and my/ mine and Olivers boards and kits.? So many things to do and never enough time! ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch – K9ZC Staunton, Illinois ? Owner – Operator Villa Grand Piton – J68HZ Soufriere, St. Lucia W.I. Rent it: ? Moderator: North American QRO Group at Groups.IO. Moderator: Amateur Radio Builders Group at Groups.IO. ? email:? bill@... ? ? toggle quoted message Show quoted text From: [email protected] <[email protected]> On Behalf Of Tim via groups.io Sent: Sunday, April 6, 2025 3:14 PM To: [email protected] Subject: Re: [SoftwareControlledHamRadio] More testing on PA ? I rewound t1,2 and 3. Tested between each rewind, tuned out T3 was culprit, easiest to wind! Not sure what it was ,I may have had a solder bridge across C25 which on revised board is right next to center tap pad. I would suggest moving that if you revise board. Seems very easy to bridge when soldering center tap windings. 100pF across primary, 7 turns on L2 (enamel wire). I may play a bit with cap across primary but it looks so much nicer now I may just leave it alone! Tim?
Greg KF5N All Messages By This Member #33385 Hi Tim- ? Check out this post I made a while ago with some videos showing sweeps of the amplifier: /g/SoftwareControlledHamRadio/message/31850 ? You have to be careful with the input drive level to keep the amplifier out of compression. If it compresses at the low frequency end, it will give a false impression of gain flatness. ? I'm not in front of my own Siglent VNA, but I think the lowest output of the TG is -10dBm. So you might need to combine that with an attenuator on the input to get a linear (no compression) sweep. ? -- 73 Greg KF5N
Tim All Messages By This Member #33388 TNX Greg. I will try reducing input and do more sweeps. I had 40db attenuation on output. There a lot more gain on lower frequencies for sure, have you tried changing L2?? I have 7 turns on it now. Tim W4YN
Tim All Messages By This Member #33403 Greg You are correct very easy to over drive 160-80M. I tried lowering input but 6m really suffered. I changed a lot of caps across input to t3 with lower drive but just could not get 6M close. I started taking turns off L2 which started at 6uH. Tried the cap switching on each turn I removed, kept getting better. Ended up with 3uH and 68pF cap across primary. -2dB input. I had the high gain on low bands building a 2kw LDMOS amp.? A friend came up with a attenuator tuned for .5-1.4 Mhz I installed on input. I believe we can compensate with carful drive input tuning on T41. Tim W4YN ?

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