Bill, is this what you want?
On 4/2/2025 10:46 AM, K9HZ via
groups.io wrote:
Take a
picture of the driver board in place on the MAIN board
please＃
?
One thing
I did that I regret is placing the ※U1§ symbol at the bottom
of the IC.? The little white registration dot for PIN 1 is
at the bottom right.
?
?
Dr.
William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ
VP5/K9HZ PJ2/K9HZ VP2EHZ
?
Owner -
Operator
Big
Signal Ranch 每 K9ZC
Staunton,
Illinois
?
Owner 每
Operator
Villa Grand
Piton 每 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@...
?
?
?
Completed the build for 5V. No shorts, no opens, and all
connections traced and ok. However, with the Board in place,
no Display. Checked it twice and made sure that both
connectors were fully seated. The system still works without
it, so no harm. I'll try again later and check some voltages.
On 3/31/2025 6:36 AM, Oliver KI3P via
groups.io wrote:
On Sunday, March 30th, 2025 at 2:47 PM,
Robert Luken W3RDL via groups.io <now.w3rdl@...>
wrote:
Got it yesterday, heading out to the workshop to build
it. May have missed your note on 5v/3.3v.
On 3/30/2025 1:55 PM, K9HZ via
groups.io wrote:
I sent out five of those new
display driver boards about a week ago and only saw
posted that Terrance got his working as was able to
use a 3-foot long display cable without display-T41
errors/lockups. Anyone else built it yet? I know i
didnt publish an assembly manual before i headed out
of the country but the thing is pretty simple and i
did send out a note re how to make it work on 5v or
3.3v.
Anyone else? I think its a winner
but would like to know so i can get parts and boards
ordered to send these out before Hamvention
?
Dr. William J. Schmidt -
K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ
PJ2/K9HZ
Owner - Operator
Big Signal Ranch 每 K9ZC
Staunton, Illinois
Owner 每 Operator
Villa Grand Piton - J68HZ
Soufriere, St. Lucia W.I.
Rent it:
?
email: bill@...
--
73 
Bob W3RDL
?
--
73
Bob W3RDL
--
73
Bob W3RDL
|
My 4 poles mesh filters results :
|
? This one too＃ ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch 每 K9ZC Staunton, Illinois ? Owner 每 Operator Villa Grand Piton 每 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 K9HZ
Sent: Wednesday, April 2, 2025 10:38 AM
To: [email protected]
Subject: Re: [AmateurRadioBuilders] More BPF Results? This company carries them in the USA: ?
? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch 每 K9ZC Staunton, Illinois ? Owner 每 Operator Villa Grand Piton 每 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@... ? ? ? I got the T37-7s from Power Magnetics in the UK: They offer fast and reliable shipping to the States.
|
This company carries them in the USA: ?
? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch 每 K9ZC Staunton, Illinois ? Owner 每 Operator Villa Grand Piton 每 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 John Bennett via groups.io
Sent: Wednesday, April 2, 2025 10:09 AM
To: [email protected]
Subject: Re: [AmateurRadioBuilders] More BPF Results? I got the T37-7s from Power Magnetics in the UK: They offer fast and reliable shipping to the States.
|
I got the T37-7s from Power Magnetics in the UK:
They offer fast and reliable shipping to the States.
73,
john
|
Nice work John
?
Where did you find t37-7 cores seem to be very scarce.
Tim W4YN
|
Take a picture of the driver board in place on the MAIN board please＃ ? One thing I did that I regret is placing the ※U1§ symbol at the bottom of the IC.? The little white registration dot for PIN 1 is at the bottom right. ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch 每 K9ZC Staunton, Illinois ? Owner 每 Operator Villa Grand Piton 每 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 Robert Luken W3RDL via groups.io
Sent: Monday, March 31, 2025 1:59 PM
To: [email protected]
Subject: Re: [AmateurRadioBuilders] Display driver board? Completed the build for 5V. No shorts, no opens, and all connections traced and ok. However, with the Board in place, no Display. Checked it twice and made sure that both connectors were fully seated. The system still works without it, so no harm. I'll try again later and check some voltages. On 3/31/2025 6:36 AM, Oliver KI3P via groups.io wrote: On Sunday, March 30th, 2025 at 2:47 PM, Robert Luken W3RDL via groups.io <now.w3rdl@...> wrote:
Got it yesterday, heading out to the workshop to build it. May have missed your note on 5v/3.3v. On 3/30/2025 1:55 PM, K9HZ via groups.io wrote: I sent out five of those new display driver boards about a week ago and only saw posted that Terrance got his working as was able to use a 3-foot long display cable without display-T41 errors/lockups. Anyone else built it yet? I know i didnt publish an assembly manual before i headed out of the country but the thing is pretty simple and i did send out a note re how to make it work on 5v or 3.3v. Anyone else? I think its a winner but would like to know so i can get parts and boards ordered to send these out before Hamvention ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ Owner - Operator Big Signal Ranch 每 K9ZC Staunton, Illinois Owner 每 Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: ? email: bill@...
-- 73  Bob W3RDL
?
--
73 Bob W3RDL
|
Excellent report John.? One question; does your measured response include the RF Switches?? Attached are my notes on the BPF. dave, n3ds
I just uploaded the results of a T41 BPF redesign, the salient features of which are as follows:
1) All filters were re-simulated in ELSIE using AI6YM kit capacitor values (which differ slightly from K9HZ values as shown in the attached file).
2) ARRL and Toroid.Info toroid material recommended frequency ranges and tolerances were taken into consideration.
3) No Type 0 (phenolic) material toroids were used. At least for me, these produce inductance values all over the place.
4) Air coils were used for all very small values of inductance.
5) All toroids were wound with 28 gauge wire. Heavier gauge (22 or 24) was used for air core inductors.
6) Inductor values were checked with LCR meter and ※pre-tuned§ prior to insertion. In some cases a turn had to be added or removed from the calculated number in order to obtain a better value.
7) The filter as a whole was then tuned until loss was less than at least 3 dBm for entire range.
8) Filter performance was measured with calibrated and normalized DSA832-TG spectrum analyzer, then saved.
9) Filter ELSIE simulated vs. measured performance was displayed using custom Python program.
10) Design details and resulting performance are in the posted file. I expect that even better performance is possible with more fussing.
Design files available upon request.
?
73,
John Bennett
AE0AM
?
?
|
That is very nice filter performance, and even better documentation! Thank you for sharing it.
On Tuesday, April 1st, 2025 at 1:15 PM, John Bennett via groups.io <jkb@...> wrote:
I just uploaded the results of a T41 BPF redesign, the salient features of which are as follows:
1) All filters were re-simulated in ELSIE using AI6YM kit capacitor values (which differ slightly from K9HZ values as shown in the attached file).
2) ARRL and Toroid.Info toroid material recommended frequency ranges and tolerances were taken into consideration.
3) No Type 0 (phenolic) material toroids were used. At least for me, these produce inductance values all over the place.
4) Air coils were used for all very small values of inductance.
5) All toroids were wound with 28 gauge wire. Heavier gauge (22 or 24) was used for air core inductors.
6) Inductor values were checked with LCR meter and ※pre-tuned§ prior to insertion. In some cases a turn had to be added or removed from the calculated number in order to obtain a better value.
7) The filter as a whole was then tuned until loss was less than at least 3 dBm for entire range.
8) Filter performance was measured with calibrated and normalized DSA832-TG spectrum analyzer, then saved.
9) Filter ELSIE simulated vs. measured performance was displayed using custom Python program.
10) Design details and resulting performance are in the posted file. I expect that even better performance is possible with more fussing.
Design files available upon request.
?
73,
John Bennett
AE0AM
?
?
|
I just uploaded the results of a T41 BPF redesign, the salient features of which are as follows:
1) All filters were re-simulated in ELSIE using AI6YM kit capacitor values (which differ slightly from K9HZ values as shown in the attached file).
2) ARRL and Toroid.Info toroid material recommended frequency ranges and tolerances were taken into consideration.
3) No Type 0 (phenolic) material toroids were used. At least for me, these produce inductance values all over the place.
4) Air coils were used for all very small values of inductance.
5) All toroids were wound with 28 gauge wire. Heavier gauge (22 or 24) was used for air core inductors.
6) Inductor values were checked with LCR meter and ※pre-tuned§ prior to insertion. In some cases a turn had to be added or removed from the calculated number in order to obtain a better value.
7) The filter as a whole was then tuned until loss was less than at least 3 dBm for entire range.
8) Filter performance was measured with calibrated and normalized DSA832-TG spectrum analyzer, then saved.
9) Filter ELSIE simulated vs. measured performance was displayed using custom Python program.
10) Design details and resulting performance are in the posted file. I expect that even better performance is possible with more fussing.
Design files available upon request.
?
73,
John Bennett
AE0AM
?
?
|
It is now working. I reflowed all of the connector pins and
verified that there was 5V on the out connector. Apparently a bad
solder joint, they looked fine though. I was able to compile and
load Ver66.9 with Faster with LTO, 528 MHz, and Dual Serial. This
would only run at 600MHz prior to the Driver board. Still not sure
why defining TCXO causes the 528MHz issue. I'll make a longer
Display cable and try it, current one is ~3".
On 3/31/2025 2:59 PM, Robert Luken
W3RDL via groups.io wrote:
Completed the build for 5V. No shorts, no opens, and all
connections traced and ok. However, with the Board in place, no
Display. Checked it twice and made sure that both connectors
were fully seated. The system still works without it, so no
harm. I'll try again later and check some voltages.
On 3/31/2025 6:36 AM, Oliver KI3P via
groups.io wrote:
Here it is:
On Sunday, March 30th, 2025 at
2:47 PM, Robert Luken W3RDL via groups.io <now.w3rdl@...>
wrote:
Got it yesterday, heading out to the workshop to build
it. May have missed your note on 5v/3.3v.
On 3/30/2025 1:55 PM, K9HZ via
groups.io wrote:
I sent out five of those new
display driver boards about a week ago and only saw posted
that Terrance got his working as was able to use a 3-foot
long display cable without display-T41 errors/lockups.
Anyone else built it yet? I know i didnt publish an
assembly manual before i headed out of the country but the
thing is pretty simple and i did send out a note re how to
make it work on 5v or 3.3v.
Anyone else? I think its a winner but would like to
know so i can get parts and boards ordered to send these
out before Hamvention
Dr.
William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ
PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
Owner
- Operator
Big
Signal Ranch 每 K9ZC
Staunton,
Illinois
Owner
每 Operator
Villa
Grand Piton - J68HZ
Soufriere,
St. Lucia W.I.
Rent
it:
email:
bill@...
--
73 
Bob W3RDL
--
73
Bob W3RDL
--
73
Bob W3RDL
|
Completed the build for 5V. No shorts, no opens, and all
connections traced and ok. However, with the Board in place, no
Display. Checked it twice and made sure that both connectors were
fully seated. The system still works without it, so no harm. I'll
try again later and check some voltages.
On 3/31/2025 6:36 AM, Oliver KI3P via
groups.io wrote:
Here it is:
On Sunday, March 30th, 2025 at 2:47
PM, Robert Luken W3RDL via groups.io
<now.w3rdl@...> wrote:
Got it yesterday, heading out to the workshop to build it.
May have missed your note on 5v/3.3v.
On 3/30/2025 1:55 PM, K9HZ via
groups.io wrote:
I sent out five of those new display
driver boards about a week ago and only saw posted that
Terrance got his working as was able to use a 3-foot long
display cable without display-T41 errors/lockups. Anyone
else built it yet? I know i didnt publish an assembly manual
before i headed out of the country but the thing is pretty
simple and i did send out a note re how to make it work on
5v or 3.3v.
Anyone else? I think its a winner but would like to
know so i can get parts and boards ordered to send these
out before Hamvention
Dr.
William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ
PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
Owner
- Operator
Big
Signal Ranch 每 K9ZC
Staunton,
Illinois
Owner
每 Operator
Villa
Grand Piton - J68HZ
Soufriere,
St. Lucia W.I.
Rent
it:
email:
bill@...
--
73 
Bob W3RDL
--
73
Bob W3RDL
|
Here it is:
On Sunday, March 30th, 2025 at 2:47 PM, Robert Luken W3RDL via groups.io <now.w3rdl@...> wrote:
Got it yesterday, heading out to the workshop to build it. May
have missed your note on 5v/3.3v.
On 3/30/2025 1:55 PM, K9HZ via
groups.io wrote:
I sent out five of those new display driver boards about a week
ago and only saw posted that Terrance got his working as was able
to use a 3-foot long display cable without display-T41
errors/lockups. Anyone else built it yet? I know i didnt publish
an assembly manual before i headed out of the country but the
thing is pretty simple and i did send out a note re how to make it
work on 5v or 3.3v.
Anyone else? I think its a winner but would like to know so
i can get parts and boards ordered to send these out before
Hamvention
Dr. William
J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ
PJ2/K9HZ
Owner -
Operator
Big
Signal Ranch 每 K9ZC
Staunton,
Illinois
Owner 每
Operator
Villa
Grand Piton - J68HZ
Soufriere,
St. Lucia W.I.
Rent it:
email: bill@...
--
73
Bob W3RDL
|
Got it yesterday, heading out to the workshop to build it. May
have missed your note on 5v/3.3v.
On 3/30/2025 1:55 PM, K9HZ via
groups.io wrote:
I sent out five of those new display driver boards about a week
ago and only saw posted that Terrance got his working as was able
to use a 3-foot long display cable without display-T41
errors/lockups. ?Anyone else built it yet? ?I know i didnt publish
an assembly manual before i headed out of the country but the
thing is pretty simple and i did send out a note re how to make it
work on 5v or 3.3v. ?
Anyone else? ? I think its a winner but would like to know so
i can get parts and boards ordered to send these out before
Hamvention
Dr.?William
J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ
PJ2/K9HZ
?
Owner -
Operator
Big
Signal Ranch 每 K9ZC
Staunton,
Illinois
?
Owner 每
Operator
Villa
Grand Piton - J68HZ
Soufriere,
St. Lucia W.I.
Rent it:
email:??bill@...
?
--
73
Bob W3RDL
|
No issues. ?It went out to others capable of building it and commenting. ?
Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch 每 K9ZC Staunton, Illinois ? Owner 每 Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com
email:??bill@... ?
toggle quoted message
Show quoted text
On Mar 30, 2025, at 1:40?PM, Albert Peter via groups.io <albertfpeter@...> wrote:
?
Bill, I have not had time to get to it: working on the book, update helping my grandson study for his pilot exam, etc. As soon as I can i will try it out.
Al
I sent out five of those new display driver boards about a week ago and only saw posted that Terrance got his working as was able to use a 3-foot long display cable without display-T41 errors/lockups. ?Anyone else built it yet? ?I know i didnt
publish an assembly manual before i headed out of the country but the thing is pretty simple and i did send out a note re how to make it work on 5v or 3.3v. ?
Anyone else? ? I think its a winner but would like to know so i can get parts and boards ordered to send these out before Hamvention
Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
?
Owner - Operator
Big Signal Ranch 每 K9ZC
Staunton, Illinois
?
Owner 每 Operator
Villa Grand Piton - J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com
email:??bill@...
?
|
Bill, I have not had time to get to it: working on the book, update helping my grandson study for his pilot exam, etc. As soon as I can i will try it out.
Al
toggle quoted message
Show quoted text
I sent out five of those new display driver boards about a week ago and only saw posted that Terrance got his working as was able to use a 3-foot long display cable without display-T41 errors/lockups. ?Anyone else built it yet? ?I know i didnt
publish an assembly manual before i headed out of the country but the thing is pretty simple and i did send out a note re how to make it work on 5v or 3.3v. ?
Anyone else? ? I think its a winner but would like to know so i can get parts and boards ordered to send these out before Hamvention
Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
?
Owner - Operator
Big Signal Ranch 每 K9ZC
Staunton, Illinois
?
Owner 每 Operator
Villa Grand Piton - J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com
email:??bill@...
?
|
I sent out five of those new display driver boards about a week ago and only saw posted that Terrance got his working as was able to use a 3-foot long display cable without display-T41 errors/lockups. ?Anyone else built it yet? ?I know i didnt publish an assembly manual before i headed out of the country but the thing is pretty simple and i did send out a note re how to make it work on 5v or 3.3v. ?
Anyone else? ? I think its a winner but would like to know so i can get parts and boards ordered to send these out before Hamvention
Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch 每 K9ZC Staunton, Illinois ? Owner 每 Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com
email:??bill@... ?
|
Small latching relays for RF switching
I have for my AT kot but nothing else. ? Didn't make sense for the cost of the relays. ?
Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch 每 K9ZC Staunton, Illinois ? Owner 每 Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com
email:??bill@... ?
Begin forwarded message:
toggle quoted message
Show quoted text
From: "Mark Frost via groups.io" <mark.frost@...> Date: March 28, 2025 at 12:38:22?AM AST To: [email protected]Subject: [AmateurRadioBuilders] Small latching relays for RF switchingReply-To: [email protected]
? Has anyone know of further experiments done along the lines of this, but with smaller relays suitable for portable/QRP applications?
I see the IM43 relays being used in the (tr)uSDX
Axicom D2n relays have been swapped into the uBitX.
Stock uBitX uses VRS2H, which is hard to find.
Browsing the digikey catalog there are several other series of small latching relays that I don't see any reference to (in ham related gear, at least). Has anyone played with the alternatives? Anyone have data?
73, Mark AC9VC
|
Small latching relays for RF switching
Has anyone know of further experiments done along the lines of this, but with smaller relays suitable for portable/QRP applications?
I see the IM43 relays being used in the (tr)uSDX
Axicom D2n relays have been swapped into the uBitX.
Stock uBitX uses VRS2H, which is hard to find.
Browsing the digikey catalog there are several other series of small latching relays that I don't see any reference to (in ham related gear, at least). Has anyone played with the alternatives? Anyone have data?
73, Mark AC9VC
|
I have no knowledge of caps across C2 and what that may do＃. ?
Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch 每 K9ZC Staunton, Illinois ? Owner 每 Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com
email:??bill@... ?
toggle quoted message
Show quoted text
On Mar 20, 2025, at 12:20?PM, D Solt via groups.io <davesolt@...> wrote:
? The cap across the primary of T2 on my PA is for gain shaping.
The oscillation continues with the BPF and the LPF out of the circuit.? I notice that additional grounding on the TR switch lowered the amplitude of the oscillation (2amps to 1amp).? I brought more ground up through J17.2 pins 4 and 5, (after I removed U18).? Still oscillates, but lower amplitude
I tried some low pass filtering on the receive line down to the LPF-Control board.? That reduces the oscillation, but doesn't eliminate it.
dave Ok you have a lot of good equipment to solve this. ? Yeah it would not hurt to try shorting over the relay on the daughter board. ? I would also try removing the BPF board and just use a jumper to reduce the number of things in line.? I would expect an oscillatory behavior if one of the TR switches either on the BPF or on the LPF was not switching correctly (so feeding back in TX).? Those things are really small and just a tiny drop of solder could cause it. ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch 每 K9ZC Staunton, Illinois ? Owner 每 Operator Villa Grand Piton 每 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@... ? ? ? I have a TinySA, NanoVNA, 50MHz scope, DVM's, Taidacent Pwr Mtr, KiwiSDR, audio generators, assorted dummy loads, attenuators, and couplers. I used the NanoVNA to sweep the 20 wt Power Amp (I built 2 of them last year) and they were very flat and stable from 3-50 MHz at 12VDC and ~1.5ADC and ~5 wt output. I have put 22 AWG wire over all the TR switch RF output tracks.? I have soldered the TR Switch into the circuit to rule out connector issues.? The amplifier works great with the home built TR switch bypass perf board (from 3-54MHz).? It oscillates with the TR switch installed on the 12, 10, and 6 meter bands at roughly 33MHz and drawing about 2ADC when the PTT is engaged.? In CW mode it has the desired frequency and the rogue 33 MHz. Tomorrow, I'll get the NanoVNA and sweep the TR Switch circuit from J23 (FROM LPF) on the LPF-Cntl board to ANT1 with the PTT engaged.? Maybe that will give me a clue. I have 2 TR Switch boards - both exhibit this behavior.? The relays are working fine at 21MHz, so don't think they are the problem.? Thanks for your help. ? First off＃ what sort of test equipment do you have Dave? ? Just stuff like DVMs or do you have something like a VNA or a Spectrum Analyzer? And possibly a signal generator or another radio you can test this PA on? ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch 每 K9ZC Staunton, Illinois ? Owner 每 Operator Villa Grand Piton 每 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@... ? ? ? I get back tonight.? Ill have some simple tests cooked up to get to the bottom of this.? ? Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch 每 K9ZC Staunton, Illinois ? Owner 每 Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: ? email:??bill@... ? ? On Mar 17, 2025, at 10:28?AM, D Solt via <davesolt@...> wrote:
? So, I am still tracking down the 20W amp oscillation, and making progress.? I have C24 in the amp, although it makes no difference to the oscillation in the high bands.? I also have the onboard attenuator in the PA.? Bypassing the BPF and the LPF made no difference to the oscillation.? Ferrites, RF chokes, and additional bypassing right on the center tap of the output transformer made no difference. The oscillation goes away when I take the output of the LPF directly to the dummy load bypassing the SWR circuit and the Transmitt Receive Switch.? I wonder if I have something wired up wrong in the transformer or the switch. Thanks again for all of your help. ? Sounds like the inpuu connection to the PA is high impedance (like something is not connected on the boads in front of the PA).. ?you migjt take the BpF put of the circuit temporarily.? Just jumper across it on the LPF board pr remove ?the LPF too just temporarily. ? ? Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch 每 K9ZC Staunton, Illinois ? Owner 每 Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: ? email:??bill@... ? ?Thanks Jerry and Bill. I＊ll get back to this on Monday. 3 dB pad on input of PA reduces oscillation, 6 dB pad stops the oscillation? ?Remove the bpf and see what happens. ? ? Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch 每 K9ZC Staunton, Illinois ? Owner 每 Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: ? email:??bill@... ? ?Yes, I agree. The amp is solid. Previously , I swept the amps and got solid performance. And, when I disconnect the drive to the amp the oscillation stops. It is being caused by something in the T41 interacting with the amp ?Something is wrong.? The amp will NOT oscillate by itself. ?? ? Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch 每 K9ZC Staunton, Illinois ? Owner 每 Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: ? email:??bill@... ?
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