low rx sensitivity - caused by miswound toroids?

General discussion and support for the Peaberry SDR V2.

Re: low rx sensitivity - caused by miswound toroids?

Postby AE9RB » Thu Jul 10, 2014 9:03 pm

T5 could be shorted to ground. One guy with this problem found his brand new BNC-PL259 adapter was bad.
73 David AE9RB
AE9RB
Site Admin
 
Posts: 511
Joined: Thu Nov 15, 2012 5:27 am
Location: Portland, Oregon, USA (CN85ql)

Re: low rx sensitivity - caused by miswound toroids?

Postby k7kw » Fri Jul 11, 2014 10:16 pm

The signal "RX" is switching ok.
The next step is to remove T5 and check its winding. I suppose the receiver will work with it out.
Doug
k7kw
 
Posts: 19
Joined: Fri Oct 18, 2013 3:22 pm

Re: low rx sensitivity - caused by miswound toroids?

Postby W4MMP » Fri Jul 11, 2014 11:51 pm

Yes, the receiver will work without T5 in fact page 21 of the full build instructions has the builder hook up a signal generator or a real antenna to test the receive section of the Peaberry. This is before any of the transmit section is built. So pull T5 and set it aside and get the receive section working.
73
Ron / W4MMP
W4MMP
 
Posts: 579
Joined: Fri Jan 03, 2014 3:31 pm
Location: Lovettsville, Virginia FM19EG

Re: low rx sensitivity - caused by miswound toroids?

Postby k7kw » Sat Jul 12, 2014 8:48 pm

Yep, removing t5 makes no change. I can still hear some signals, but nothing less than 10uV or so. During assembly I probably thought that's all I get, but I know better now based on reports from other users.
I will move down the signal path until it's fixed. David was kind enough to send me more toroid wire. My experience with receivers is that fixing "low sensitivity" can be a bugger.
Doug
k7kw
 
Posts: 19
Joined: Fri Oct 18, 2013 3:22 pm

Re: low rx sensitivity - caused by miswound toroids?

Postby W4MMP » Tue Jul 29, 2014 4:49 pm

k7kw wrote:Yep, removing t5 makes no change. I can still hear some signals, but nothing less than 10uV or so. During assembly I probably thought that's all I get, but I know better now based on reports from other users.
I will move down the signal path until it's fixed. David was kind enough to send me more toroid wire. My experience with receivers is that fixing "low sensitivity" can be a bugger.
Doug


Hi,
Any luck?
73
Ron / W4MMP
W4MMP
 
Posts: 579
Joined: Fri Jan 03, 2014 3:31 pm
Location: Lovettsville, Virginia FM19EG

Re: low rx sensitivity - caused by miswound toroids?

Postby KD31 » Wed Feb 25, 2015 5:44 pm

I have the same issue, did yours ever get sorted out?
KD31
 
Posts: 13
Joined: Wed Feb 25, 2015 8:01 am

Re: low rx sensitivity - caused by miswound toroids?

Postby mrwizardly » Wed Feb 25, 2015 8:57 pm

Did you check the receiver sensitivity before adding all the bandpass toroids on page 20???
I left a small cat-whisker on C27, near side (away from Q1) to inject a signal (as described) to be sure I was getting the same signal input through the bandpass toroids (through the antenna) as next to the FET blocking cap.
I had to rewind T2 because the burrs on the binocular toroid chaffed some of the enamel from the wires causing them to short. Fixing that popped up my sensitivity so high that I almost could not turn my signal generator low enough for -40dbm.
You will definitely need a signal generator & scope to do the checkout. Don't use a transmitter. You cannot get the power low enough, PERIOD!
You may have to resort to what it says in the last paragraph on page 20:
If you don't have equipment...
Fixing T2 made my V2 as sensitive as my Icom 7600 !!!
Mark
W7EAZ
mrwizardly
 
Posts: 43
Joined: Sun Jan 25, 2015 3:47 am

Previous

Return to Peaberry SDR V2

Who is online

Users browsing this forum: No registered users and 2 guests

cron