Tnx for your answer, Wes.
I meant to say "LOW PASS FILTER" (for the final amp), not BPF.
The BPF is only used for the RX and it is working OK.
IMO it must be this LPF circuit, and it has just 2 coils and 3 caps.
But of course you can't really get at it to see or measure anything.
(Murphy)
I don't agree with your logic (but I am not sure).
Normally the input to the bridge (from the LPF) would be a nominal 50 Ohms
and on the dummy as it is, also 50 Ohms.
If either side changes, it causes an imbalance and shows high SWR.
I think I'm going to have to get out a BIG soldering iron and try to remove
the metal shielding around the circuit so that I can pull and measure the 5
components in the LPF. I hope I don't burn up the board.
But first I'm going to try bypassing the LPF entirely and just running the
power straight to the dummy.
If it's 50 Ohms, then I will know the problem is the LPF.
It's easy in theory but tough to get at inside the radio.
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Wes Attaway
(N5WA)
Sent: Tuesday, July 15, 2014 5:36 PM
To: 'Discussion of Ten-Tec Equipment'
Subject: Re: [TenTec] Scout has vy low Pwr out on some bands
I don't know anything about the radio, but it seems like if the BPF is
causing an SWR problem then the SWR would have to be measured at some point
between the TX output and the BPF (ahead of the BPF rather than after it).
Is this the way the schematic shows it?
I guess you could connect an external SWR meter to confirm this idea. An
external SWR meter should not be affected by the BPF.
----------------- Wes Attaway (N5WA) -------------------
1138 Waters Edge Circle, Shreveport, LA 71106
--- 318-393-3289 (Cell) ---
Computer Consulting and Forensics
-------------- EnCase Certified Examiner ---------------
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Rick -
DJ0IP / NJ0IP
Sent: Tuesday, July 15, 2014 9:39 AM
To: 'Discussion of Ten-Tec Equipment'
Subject: [TenTec] Scout has vy low Pwr out on some bands
I received my new (used) Scout yesterday.
After a long search, I finally found a power plug and 9A Airpax circuit
breaker in my junkbox.
I built a cable with the breaker and am powering it from a 963.
The Scout came with band modules for all bands except 17 & 12.
There is no NB.
The RX seems to work fine on all bands.
On two of the bands (160 and 40m), I get very low output power - about 8w
and 2w.
On all other bands it easily brings 50+ watts on my cheap watt meter (10%
accuracy).
I changed modules quite a lot, making tests first on a dummy and then on an
antenna.
At one point 40m suddenly worked, with full output power.
I made several 40m SSB QSOs with it.
Later when I plugged the 40m band module back in, the power was again 2w.
When I get the 2w, the SWR also shoots up. When it was working properly,
the SWR was good.
I have studied the diagram of the band modules.
Since the RX seems to work properly, I assume the oscillator and mixer of
these modules are working OK, as well as the HPF on the 160m module and the
LPF on the 40m module.
The only thing left is the actual Bandpass Filter for the TX. It is
encapsulated in shielding and I can't really get at it.
I have re-soldered all connections on the bottom of the PC board but no
change. Still 2w.
I can't see how it would be anything but the BPF - or am I missing
something.
Any tips?
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
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