diff --git a/.github/workflows/ci-test.yml b/.github/workflows/ci-test.yml
index 7627f658..ca4e5039 100644
--- a/.github/workflows/ci-test.yml
+++ b/.github/workflows/ci-test.yml
@@ -28,7 +28,6 @@ jobs:
             g++ \
             gcc \
             git \
-            gnuradio-dev \
             libboost-all-dev \
             libev-dev \
             libopencv-dev \
@@ -41,6 +40,10 @@ jobs:
             uhd-host \
             wget \
           && grep -h 'git clone' docker/*|grep -v pytorch|sed -E 's/RUN\s+git clone\s+//g'|sort|uniq|xargs -L1 git clone
+      - name: install gnuradio
+        run: |
+          sudo add-apt-repository ppa:gnuradio/gnuradio-releases && sudo apt-get update && \
+            sudo apt-get install -y --no-install-recommends gnuradio-dev python3-packaging
       - name: Install dependencies
         run: |
           for repodir in flatbuffers json libsigmf gr-iqtlabs ; do \
diff --git a/gamutrf/grsource.py b/gamutrf/grsource.py
index 8d59527b..2596b7ac 100644
--- a/gamutrf/grsource.py
+++ b/gamutrf/grsource.py
@@ -87,6 +87,10 @@ def work(self, input_items, output_items):
         return len(samples)
 
 
+def get_throttle(samp_rate, items=1024):
+    return blocks.throttle(gr.sizeof_gr_complex, samp_rate, True, items)
+
+
 def get_source(
     sdr,
     samp_rate,
@@ -110,7 +114,7 @@ def get_source(
         if url.scheme == "file" and os.path.exists(url.path):
             sources = [
                 file_source_tagger(url.path, cmd_port),
-                blocks.throttle(gr.sizeof_gr_complex, samp_rate, True),
+                get_throttle(samp_rate),
             ]
         else:
             raise ValueError("unsupported/missing file location")
@@ -119,7 +123,7 @@ def get_source(
         cmd_port = "cmd"
         sources = [
             iqtlabs.tuneable_test_source(freq_divisor),
-            blocks.throttle(gr.sizeof_gr_complex, samp_rate, True),
+            get_throttle(samp_rate),
         ]
     elif sdr == "ettus":
         sources = get_ettus_source(sdrargs, samp_rate, center_freq, agc, gain, uhd_lib)